Academic literature on the topic 'Seed dispersal network'
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Journal articles on the topic "Seed dispersal network"
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Rehm, E., E. Fricke, J. Bender, J. Savidge, and H. Rogers. "Animal movement drives variation in seed dispersal distance in a plant–animal network." Proceedings of the Royal Society B: Biological Sciences 286, no. 1894 (January 16, 2019): 20182007. http://dx.doi.org/10.1098/rspb.2018.2007.
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Frugivores play differing roles in shaping dispersal patterns yet seed dispersal distance is rarely quantified across entire communities. We model seed dispersal distance using gut passage times and bird movement for the majority (39 interactions) of known bird–tree interactions on the island of Saipan to highlight differences in seed dispersal distances provided by the five avian frugivores. One bird species was found to be a seed predator rather than a disperser. The remaining four avian species dispersed seeds but differences in seed dispersal distance were largely driven by interspecific variation in bird movement rather than intraspecific variation in gut passage times. The median dispersal distance was at least 56 m for all species-specific combinations, indicating all species play a role in reducing high seed mortality under the parent tree. However, one species—the Micronesian Starling—performed 94% of dispersal events greater than 500 m, suggesting this species could be a key driver of long-distance dispersal services (e.g. linking populations, colonizing new areas). Assessing variation in dispersal patterns across this network highlights key sources of variation in seed dispersal distances and suggests which empirical approaches are sufficient for modelling how seed dispersal mutualisms affect populations and communities.
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Lavabre, Jessica E., Luis J. Gilarranz, Miguel A. Fortuna, and Jordi Bascompte. "How does the functional diversity of frugivorous birds shape the spatial pattern of seed dispersal? A case study in a relict plant species." Philosophical Transactions of the Royal Society B: Biological Sciences 371, no. 1694 (May 19, 2016): 20150280. http://dx.doi.org/10.1098/rstb.2015.0280.
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Genetic markers used in combination with network analysis can characterize the fine spatial pattern of seed dispersal and assess the differential contribution of dispersers. As a case study, we focus on the seed dispersal service provided by a small guild of frugivorous birds to the common yew, Taxus baccata L., in southern Spain. We build the spatial networks of seed dispersal events between trees and seed-plots within the studied population—local network—and the spatial network that includes all dispersal events—regional network. Such networks are structured in well-defined modules, i.e. groups of tightly connected mother trees and seed-plots. Neither geographical distance, nor microhabitat type explained this modular structure, but when long-distance dispersal events are incorporated in the network it shows a relative increase in overall modularity. Independent field observations suggested the co-occurrence of two complementary groups, short- and long-distance dispersers, mostly contributing to the local and regional seed rain, respectively. The main long-distance disperser at our site, Turdus viscivorus , preferentially visits the most productive trees, thus shaping the seed rain at the landscape scale and affecting the local modular organization. We end by discussing how DNA barcoding could serve to better quantify the role of functional diversity.
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Heleno, Ruben H., Jens M. Olesen, Manuel Nogales, Pablo Vargas, and Anna Traveset. "Seed dispersal networks in the Galápagos and the consequences of alien plant invasions." Proceedings of the Royal Society B: Biological Sciences 280, no. 1750 (January 7, 2013): 20122112. http://dx.doi.org/10.1098/rspb.2012.2112.
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Alien plants are a growing threat to the Galápagos unique biota. We evaluated the impact of alien plants on eight seed dispersal networks from two islands of the archipelago. Nearly 10 000 intact seeds from 58 species were recovered from the droppings of 18 bird and reptile dispersers. The most dispersed invaders were Lantana camara , Rubus niveus and Psidium guajava , the latter two likely benefiting from an asynchronous fruit production with most native plants, which facilitate their consumption and spread. Lava lizards dispersed the seeds of 27 species, being the most important dispersers, followed by small ground finch, two mockingbirds, the giant tortoise and two insectivorous birds. Most animals dispersed alien seeds, but these formed a relatively small proportion of the interactions. Nevertheless, the integration of aliens was higher in the island that has been invaded for longest, suggesting a time-lag between alien plant introductions and their impacts on seed dispersal networks. Alien plants become more specialized with advancing invasion, favouring more simplified plant and disperser communities. However, only habitat type significantly affected the overall network structure. Alien plants were dispersed via two pathways: dry-fruited plants were preferentially dispersed by finches, while fleshy fruited species were mostly dispersed by other birds and reptiles.
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Heleno, Ruben H., Jaime A. Ramos, and Jane Memmott. "Integration of exotic seeds into an Azorean seed dispersal network." Biological Invasions 15, no. 5 (November 27, 2012): 1143–54. http://dx.doi.org/10.1007/s10530-012-0357-z.
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Wang, Biao, Hai Bin Zheng, Ying Jue Fang, and Jun Jie Wei. "Overlapping Community Detection Algorithm Based on Seed Diffusion." Applied Mechanics and Materials 556-562 (May 2014): 3300–3304. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.3300.
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Thinking applied to the seed dispersal weighted network using node strength to find seed node, and through seed nodes for each node fitness Looking node's home societies, and update the node in the iterative process of fitness makes societies divided stabilized. The experimental results show that the network based on the weighted overlap Societies seed dispersal algorithm can be found in weighted social networks effectively divided and divided more tends to be refined.
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Acosta-Rojas, Diana Carolina, María Victoria Jiménez-Franco, Víctor Manuel Zapata-Pérez, Pilar De la Rúa, and Vicente Martínez-López. "An integrative approach to discern the seed dispersal role of frugivorous guilds in a Mediterranean semiarid priority habitat." PeerJ 7 (October 11, 2019): e7609. http://dx.doi.org/10.7717/peerj.7609.
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Seed dispersal is an essential process to maintain the viability of plant populations, and understanding this ecological process allows management strategies to be developed to conserve ecosystems. European Union priority habitat 5220* is defined as “Mediterranean arborescent shrubland with Ziziphus lotus” and it represents a favorable microclimate within the severe climatic conditions typical of the semiarid south-eastern region of the Iberian Peninsula. Therefore, the study of seed dispersal in this priority habitat by different frugivorous guilds, is a challenge for its conservation. In this study, we have characterized a mutualistic network of seed dispersal that is mediated by vertebrates (mammals and birds) in the protected habitat 5220*. The aims of this study were to: (i) identify the seed disperser community; (ii) analyze the relative role of key species in the dispersal process; and (iii) compare the functional ecology of the seed dispersal process between mammals and birds. As such, we collected animal faeces to determine seed dispersers taxonomy, identifying the mammals through the visual aspect of the faeces and the birds by DNA barcoding. In the case of birds, we also collected regurgitated seeds in which the disperser species was also identified through molecular techniques. This allowed us to build-up a mutualistic network and to identify the relative role of these animals in seed dispersal. Our results showed that mammals and birds fulfilled complementary roles in seed dispersal, with birds representing the main dispersers of key plants within the 5220* habitat, and mammals the main dispersers of human-cultivated plants. Herein, we provide a useful approach with relevant information that can be used to propose management policies that focus on restoring the threatened 5220* habitat, promoting the role of birds to disperse key species that structure plant communities of this priority habitat.
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Correia, Marta, Susana Rodríguez-Echeverría, Sérgio Timóteo, Helena Freitas, and Ruben Heleno. "Integrating plant species contribution to mycorrhizal and seed dispersal mutualistic networks." Biology Letters 15, no. 5 (May 2019): 20180770. http://dx.doi.org/10.1098/rsbl.2018.0770.
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Mutualistic interactions like those established between plants and mycorrhizal fungi or seed dispersers are key drivers of plant population dynamics and ecosystem functioning; however, these interactions have rarely been explored together. We assembled a tripartite fungi–plant–disperser network in the Gorongosa National Park—Mozambique, to test (1) if diversity and importance of plant mutualists above- and belowground are correlated, and (2) whether biotically and abiotically dispersed plants are associated with distinct arbuscular mycorrhizal fungi (AMF). We quantified seed dispersal by animals for 1 year and characterized the AMF of 26 common plant species. Sixteen plant species were dispersed by 15 animals and colonized by 48 AMF virtual taxa (VT), while the remaining 10 plant species were not dispersed by animals and associated with 34 AMF VT. We found no evidence for a correlation between the number of plant partners above- and belowground or on plant specialization on both types of partners. We also found no evidence for differentiation of AMF communities between biotically and abiotically dispersed plants. Our results suggest that the establishment of plant interactions with seed dispersers and mycorrhizal fungi is largely independent and that both biotically and abiotically dispersed plants seem to associate with similar communities of AMF.
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Burin, Gustavo, Paulo R. Guimarães, and Tiago B. Quental. "Macroevolutionary stability predicts interaction patterns of species in seed dispersal networks." Science 372, no. 6543 (May 13, 2021): 733–37. http://dx.doi.org/10.1126/science.abf0556.
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Assessing deep-time mechanisms affecting the assembly of ecological networks is key to understanding biodiversity changes on broader time scales. We combined analyses of diversification rates with interaction network descriptors from 468 bird species belonging to 29 seed dispersal networks to show that bird species that contribute most to the network structure of plant–frugivore interactions belong to lineages that show higher macroevolutionary stability. This association is stronger in warmer, wetter, less seasonal environments. We infer that the macroevolutionary sorting mechanism acts through the regional pool of species by sorting species on the basis of the available relative differences in diversification rates, rather than absolute rates. Our results illustrate how the interplay between interaction patterns and diversification dynamics may shape the organization and long-term dynamics of ecological networks.
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Vizentin-Bugoni, Jeferson, Jinelle H. Sperry, J. Patrick Kelley, Jason M. Gleditsch, Jeffrey T. Foster, Donald R. Drake, Amy M. Hruska, Rebecca C. Wilcox, Samuel B. Case, and Corey E. Tarwater. "Ecological correlates of species’ roles in highly invaded seed dispersal networks." Proceedings of the National Academy of Sciences 118, no. 4 (January 11, 2021): e2009532118. http://dx.doi.org/10.1073/pnas.2009532118.
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Ecosystems with a mix of native and introduced species are increasing globally as extinction and introduction rates rise, resulting in novel species interactions. While species interactions are highly vulnerable to disturbance, little is known about the roles that introduced species play in novel interaction networks and what processes underlie such roles. Studying one of the most extreme cases of human-modified ecosystems, the island of Oʻahu, Hawaii, we show that introduced species there shape the structure of seed dispersal networks to a greater extent than native species. Although both neutral and niche-based processes influenced network structure, niche-based processes played a larger role, despite theory predicting neutral processes to be predominantly important for islands. In fact, ecological correlates of species’ roles (morphology, behavior, abundance) were largely similar to those in native-dominated networks. However, the most important ecological correlates varied with spatial scale and trophic level, highlighting the importance of examining these factors separately to unravel processes determining species contributions to network structure. Although introduced species integrate into interaction networks more deeply than previously thought, by examining the mechanistic basis of species’ roles we can use traits to identify species that can be removed from (or added to) a system to improve crucial ecosystem functions, such as seed dispersal.
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Neumann, Ulla, and Angela Hay. "Seed coat development in explosively dispersed seeds of Cardamine hirsuta." Annals of Botany 126, no. 1 (December 4, 2019): 39–59. http://dx.doi.org/10.1093/aob/mcz190.
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Abstract Background and Aims Seeds are dispersed by explosive coiling of the fruit valves in Cardamine hirsuta. This rapid coiling launches the small seeds on ballistic trajectories to spread over a 2 m radius around the parent plant. The seed surface interacts with both the coiling fruit valve during launch and subsequently with the air during flight. We aim to identify features of the seed surface that may contribute to these interactions by characterizing seed coat differentiation. Methods Differentiation of the outermost seed coat layers from the outer integuments of the ovule involves dramatic cellular changes that we characterize in detail at the light and electron microscopical level including immunofluorescence and immunogold labelling. Key Results We found that the two outer integument (oi) layers of the seed coat contributed differently to the topography of the seed surface in the explosively dispersed seeds of C. hirsuta vs. the related species Arabidopsis thaliana where seed dispersal is non-explosive. The surface of A. thaliana seeds is shaped by the columella and the anticlinal cell walls of the epidermal oi2 layer. In contrast, the surface of C. hirsuta seeds is shaped by a network of prominent ridges formed by the anticlinal walls of asymmetrically thickened cells of the sub-epidermal oi1 layer, especially at the seed margin. Both the oi2 and oi1 cell layers in C. hirsuta seeds are characterized by specialized, pectin-rich cell walls that are deposited asymmetrically in the cell. Conclusions The two outermost seed coat layers in C. hirsuta have distinct properties: the sub-epidermal oi1 layer determines the topography of the seed surface, while the epidermal oi2 layer accumulates mucilage. These properties are influenced by polar deposition of distinct pectin polysaccharides in the cell wall. Although the ridged seed surface formed by oi1 cell walls is associated with ballistic dispersal in C. hirsuta, it is not restricted to explosively dispersed seeds in the Brassicaceae.
Dissertations / Theses on the topic "Seed dispersal network"
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Amatuzzi, Maria Clara Oleski. "Redes de interação entre plantas e frugivoros na mata atlantica : estrutura e fragilidade a extinções." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316383.
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Orientadores: Wesley Rodrigues Silva, Paulo Roberto Guimarães JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: O mutualismo planta-frugívoro é bem conhecido como importante processo na manutenção dos ecossistemas. O frugívoro obtém o recurso alimentar da polpa e dispersa as sementes da planta. A crescente perda e fragmentação de ambientes naturais devem afetar essas interações. Portanto, conhecer quais são os efeitos desta degradação na dispersão de sementes é um passo importante na tentativa de preservação dos ecossistemas. A abordagem de redes vem sendo usada atualmente a fim de entender melhor a estrutura, funcionamento e evolução de diversos tipos de interações. Explorei alguns padrões de extinção de espécies em uma rede de interações mutualísticas frugívoro-planta do Parque Estadual de Intervales (PEI) simulando extinções de frugívoros e plantas e observando os efeitos na sua estrutura. A rede frugívoro-planta do PEI é uma rede típica de interações mutualísticas com estrutura extremamente aninhada; baixa conectância; baixos graus médios tanto de plantas como dos animais; prevalência de interações fracas e ocorrência de interações assimétricas. As co-extinções ocorreram muito lentamente com as remoções de especialistas e geram um declínio considerável na riqueza de espécies do outro grupo, somente após remoção de 80% das espécies. Remoções aleatórias de espécies geraram um padrão quase linear de co-extinções, após a remoção de 50% das espécies observa-se um maior impacto na riqueza da rede. A remoção das espécies ameaçadas de extinção causou impacto semelhante ao observado com as remoções aleatórias. Em geral, ocorre um padrão de surgimento de pequenos componentes, a partir da remoção de 5% das espécies, porém há sempre um grande e aninhado componente. O aninhamento da rede foi pouco modificado com as simulações. A rede perde o aninhamento mais rapidamente durante a remoção de generalistas. Os resultados reforçam a idéia de robustez dessa rede que é gerada pela suas características estruturais. As espécies mais importantes para a manutenção da estrutura e riqueza de espécies da rede são as generalistas.
Abstract: The frugivore-plant mutualism has been recognized as an important process in maintaining terrestrial ecosystems. Frugivores feed on fruits and disperse their seeds. The increase of habitat fragmentation and loss may affect these interactions. Therefore, understanding the effects of these disturbances on seed dispersal process may help to predict shifts in the remaining ecosystems. In this sense, the network approach has been used to describe the structure and investigate function and evolution of different types of interactions. I explored different patterns of extinction in a network of mutualistic frugivore-plant interactions of the Parque Estadual de Intervales (PEI) by simulating the removal of frugivores and plants and observing the effects on its structure. The PEI network as a typical mutualistic network with highly nested interactions; low connectance; small average number of interactions for both plants and animals; prevalence of weak interactions and occurrence of asymmetric interactions. When removing specialists, coextinctions occurred very slowly, leading a significant decline on species richness only after the removal of 80%. Random removal of species created an almost linear co-extinction pattern, showing important cumulative loss of species after removal of 50% of species. Species diversity declined most rapidly with the removal of the generalists. The removal of endangered species caused patterns of co-extinction similar to those caused by the random removal. In general, PEI network showed a pattern of break down of small clusters after the extinction of just 5% of species, although a large and nested cluster stil observed. The nested structure of the network was slightly changed through the simulations. The network lost its nested structure more rapidly when generalists species were removed. These simulations support the notion that mutualistic networks are robust to extinction and generalists are the most important species for the maintenance of structure and species richness of these networks.
Mestrado
Mestre em Ecologia
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Bodin, Örjan. "A network perspective on ecosystems, societies and natural resource management." Doctoral thesis, Stockholm University, Department of Systems Ecology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-844.
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This thesis employs a network perspective in studying ecosystems and natural resource management. It explores the structural characteristics of social and/or ecological networks and their implications on societies’ and ecosystems’ ability to adapt to change and to cope with disturbances while still maintaining essential functions and structures (i.e. resilience).
Paper I introduces terminology from the network sciences and puts these into the context of ecology and natural resource management. Paper II and III focus on habitat fragmentation and how it affects an agricultural landscape in southern Madagascar. Two ecosystem services were addressed: (1) crop pollination by bees, and (2) seed dispersal by ring-tailed lemurs. It is shown that the fraction of the studied landscape presently covered by both crop pollination and seed dispersal is surprisingly high, but that further removal of the smallest habitat patches in the study area could have a severe negative impact on the landscape’s capacity to support these ecosystem services.
In Papers IV and V, the network approach is used to study social networks and the impact they may have on the management of natural resources. In Paper IV it is found that social networks of low- to moderate link densities (among managers) significantly increase the probability for relatively high and stable utility returns whereas high link densities cause occasional large-scale ecological crises between periods of stable and excessively high utility returns. In Paper V, social networks of a rural fishing community in eastern Africa were analyzed. The results indicate that patterns of communication partly explain the distribution of ecological knowledge among villagers, and that gear type used by small-scale coastal fishermen strongly correlates with their patterns of communication. The results also show that groups most central in the network, and hence potentially most influential, are dominated by one type of fishermen.
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Rodrigues, Suelen Barbosa Moraes. "Redes de interações entre aves frugívoras e plantas em uma área de Mata Atlântica no sudeste do Brasil." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/8370.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Interactions plants-frugivores are key components in the complexity of forest communities and their modifications or losses can have profound implications for conservation. The study of the interactions networks has proven an important tool in understanding how communities respond to human disturbance. The aim of this study was to analyze the interactions networks between plants and birds as fruit consumers in Atlantic Forest in southeastern Brazil. The research was conducted in Carlos Botelho State Park (PECB) and addressed three environments with different types of vegetation (open area, and initial successional stages and advanced). The interactions record was performed by direct observation using methods of transect, focal and assistance traps cameras. We evaluated the frequency of visits, number of interactions, nesting and connectance. The network is represented by 63 kinds of birds and 30 species of plants and showed a nested pattern (NODF = 33.63, p = 0) with a connectance low (13%). 255 interactions were observed in 1151 records frugivory. The species that contributed most to the organization's network were also the most important for community maintenance and alien species present in one of the rooms did not interfere in the interactions between native species.
As interações entre frugívoros e plantas são componentes fundamentais na complexidade das comunidades florestais e sua modificação ou perda podem trazer profundas implicações para a conservação. O estudo das redes de interações tem se mostrado importante ferramenta no entendimento de como as comunidades respondem às perturbações antrópicas. O objetivo desse trabalho foi analisar a rede de interações entre plantas e aves consumidoras de frutos em área de Mata Atlântica no sudeste do Brasil. A pesquisa foi desenvolvida no Parque Estadual Carlos Botelho (PECB) e abordou três ambientes com diferentes tipos de vegetação (área aberta, e de estágio sucessional inicial e avançado). O registro das interações foi realizado por observações diretas pelos métodos de transecto, focal e auxílio de câmeras traps. Foram avaliadas a frequência de visitas, número de interações, o aninhamento e a conectância. A rede foi representada por 63 espécies de aves e 30 espécies de plantas e apresentou um padrão aninhado (NODF = 33,63, p = 0), com uma baixa conectância (13%). Foram observadas 255 interações em 1151 registros de frugivoria. As espécies que mais contribuíram para a organização da rede também foram as mais importantes para a manutenção da comunidade e as espécies exóticas presentes em um dos ambientes não interferiram nas interações entre as espécies nativas.
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Silva, Fernanda Ribeiro da 1978. "Redes mutualísticas na avaliação da restauração da Mata Atlântica = Mutualistic networks in evaluation of restoration in the Atlantic forest." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315538.
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Orientadores: Ricardo Ribeiro Rodrigues, Marco Aurélio Pizo FerreiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: As atividades humanas têm levado à perda de habitats e da biodiversidade na floresta Atlântica. A restauração ecológica é uma estratégia para a reconstrução desse bioma e deve incluir não só o restabelecimento das espécies, mas também das complexas interações e funções ecológicas que essas interações fornecem ao ecossistema. Um desses importantes processos é a dispersão de sementes realizada pelos animais frugívoros. A dispersão de sementes pode ser analisada numa abordagem de redes de interações, úteis no entendimento do funcionamento do ecossistema. Nós estudamos redes de dispersão de sementes em três áreas restauradas a 15, 25 e 57 anos atrás, escala temporal raramente estudada em estudos de restauração. Nós investigamos mudanças na estrutura das redes (aninhamento, modularidade e especialização da rede) em cada uma dessas comunidades ao longo do tempo de restauração. Embora o tamanho da rede e o número de interações tenham aumentado com a restauração, as espécies que compuseram a rede foram generalistas, sendo que os grandes frugívoros estiveram ausentes. Contrário a nossa expectativa, a riqueza de espécies foi maior na área de 25 anos, talvez devido ao plantio ter sido realizado com maior número de espécies. O aninhamento foi baixo nas três redes, sendo maior na área de idade intermediária. Entretanto a área mais antiga foi significativamente modular e apresentou alta especialização. Estes resultados sugerem que 57 anos após a restauração a complexidade das redes de interações mutualísticas aumentou, assim melhorando as funções ecossistêmicas na floresta Atlântica. Nós juntamos as três redes de dispersão de sementes restauradas em uma para identificar a contribuição individual das espécies na organização e funcionamento da rede, medidas pelo aninhamento, modularidade e força de interação. Através dessas abordagens apontamos as espécies e os grupos funcionais mais importantes para a resiliência e persistência das redes de dispersão de sementes e que devem ser priorizados nas ações de restauração da Mata Atlântica
Abstract: Human activities have lead to the loss of habitats and biodiversity in the Atlantic Rain Forest in Brazil. Ecological restoration aims to rebuild this biome and should include not only the reinstatement of species, but the reestablishment of complex ecological interactions and the ecological functions that they provide. One such function is seed dispersal, which is provided by the interactions between animal frugivores and plants. We studied seed dispersal networks in three different tropical forest sites restored 15, 25 and 57 years ago, temporal scales rarely observed in restoration studies. We investigated changes in network structure (nestedness, modularity and network specialization) in these communities over restoration time. Although network size and the number of interactions increased with time since restoration, the networks were composed of generalist birds, and the large frugivores remained absent. Contrary to our expectations though, species richness was highest in the 25 years old site maybe due the highest number of species used in the planting. Nestedness values were low in all three networks, but the highest nestedness was observed in the intermediate aged site. However, the oldest network was significantly modular and showed higher complementary specialization. These results suggest that, 57 years after restoration, the complexity of mutualistic interactions in seed dispersal networks has increased, this enhancing ecosystem function in the Atlantic forest. Furthermore, we merged all three networks in a big one to identify which are the most important species in terms of nerwork organization (modularity and nestedness) and interaction strength. Through this approach we point out species and their functional groups most important to persistence of seed dispersal networks. These species and their functional groups should be indicated to maximize the restoration in the Atlantic forest
Doutorado
Biologia Vegetal
Doutora em Biologia Vegetal
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Bieber, Ana Gabriela Delgado 1981. "A fragmentação florestal e a interação entre formigas e diásporos carnosos na floresta Atlântica." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316181.
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Orientador: Paulo Sérgio Moreira Carvalho de OliveiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Em florestas tropicais, formigas de folhiço são freqüentemente vistas em interação com diásporos vegetais (frutos e sementes). Em alguns casos, esta interação oportunista resulta em um mutualismo. Enquanto formigas se beneficiam ao alimentar-se de partes carnosas nutritivas (i.e., polpa, arilo), elas podem beneficiar a semente, por exemplo, ao aumentar sua chance de germinação ou ao dispersá-la para micro-sítios ricos em nutrientes. Portanto, para algumas espécies de plantas, a perda de interações formiga-diásporo pode implicar numa redução do recrutamento de novos indivíduos. Nesta tese, estudamos os padrões de interação entre formigas e diásporos em dois tipos contrastantes de florestas, representativos do que resta da Floresta Atlântica no Estado de São Paulo: florestas contínuas (CFs) e fragmentos de floresta com vegetação secundária (FFs) (quatro áreas cada). Durante este estudo, quatro abordagens complementares foram adotadas. Primeiramente, registramos as interações entre formigas e diásporos em cada uma das oito áreas durante um ano. As principais famílias de plantas assim como os principais gêneros de formigas registrados correspondem a grupos importantes já listados em estudos prévios realizados neste bioma. Apesar da abundância similar de diásporos considerados atrativos entre os dois tipos de floresta, houve um maior número de interações na floresta contínua. Esta diferença é provavelmente devida à comunidade vegetal depauperada dos fragmentos, composta por espécies menos atrativas para as formigas. Com base no mesmo conjunto de dados, comparamos se a topologia das redes de interação formiga-fruto diferiu entre os dois tipos de floresta. Três das sete métricas calculadas foram afetadas pelo tipo de floresta. A diminuição do número de espécies de plantas nos fragmentos florestais parece ser um fator-chave para justificar os resultados obtidos. Na terceira abordagem, oferecemos um diásporo sintético rico em lipídios em estações de remoção para comparar a visitação e o comportamento das formigas entre os dois tipos florestais. Em geral, um maior número de espécies de formigas foi atraído às estações das CFs. A freqüência de grandes poneríneas (em especial, Pachycondyla striata) em interação com diásporos sintéticos foi mais elevada em CFs, estando relacionada com uma maior remoção de diásporos nestas áreas. Por fim, avaliamos experimentalmente se a manipulação prévia por aves (uma condição mais comum em florestas contínuas) afeta a atratividade de diásporos caídos em relação a formigas. Para este procedimento, utilizamos o arbusto Psychotria suterella (Rubiaceae), comum no subosque de nossa área de estudo e cujos diásporos são dispersos por aves. Frutos que já tiveram contato com vertebrados apresentaram uma maior chance de interagir com formigas. Este resultado sugere que espécies vegetais em florestas fragmentadas, comumente sujeitas à perda de seus dispersores primários, ainda são afetadas pela diminuição da atratividade de frutos intactos para formigas (dispersores secundários), a despeito da abundância destes insetos no chão da floresta. De forma geral, os resultados desta tese indicam que a fragmentação da Floresta Atlântica afeta negativamente as interações formiga-diásporo. Portanto, é possível que em fragmentos florestais haja uma diminuição dos potenciais benefícios a sementes e plântulas derivados da interação com formigas, podendo repercutir negativamente no recrutamento das plantas
Abstract: In tropical rainforests, ground-dwelling ants opportunistically interact with fleshy diaspores and, in some cases, this interaction can be classified as mutualistic. While ants gain from eating the nutritious fleshy parts, they may benefit the seed in two ways: (1) greater germination success; and (2) directed dispersal to nutrient-rich microsites where seedlings grow better. Thus, for some plant species, the loss of ant-diaspore interactions may negatively affect plant recruitment. Here, we explore ant-diaspore interaction patterns in two divergent forest types, representing what has remained from the Brazilian Atlantic Forest of São Paulo State: continuous old-growth forests (CFs) and secondary forest fragments (FFs) (four sites each). During this study, four complementary approaches were adopted. First, we surveyed ant-diaspore interactions in all forest sites during one year. Main plant families and ant genera registered during our survey correspond to previous studies performed in this biome. In spite of the similar abundance of ant-attractive diaspores on the forest ground, there were striking differences on ant-diaspore interactions between continuous and fragmented forests. Differences are most certainly attributed to the species-poor plant community, composed by less attractive species, found in the fragments. Based on the same dataset, we investigated whether the topology of ant-diaspore interaction networks differed between our two studied forest types. Three out of seven network-level metrics calculated diverged between fragments and continuous forests. The decrease in the number of interacting plant species observed in the fragmented forests appears to be a key-factor for explaining the observed results. Third, we offered a lipid-rich synthetic diaspore in experimental removal stations to compare ant attendance and behavior between forest types. Again, the experiment evidenced differences between the opposing forest types. In general, a higher number of ant species was recorded in CFs. The frequency of large ponerines (mainly Pachycondyla striata) was higher in CFs, corresponding to the higher frequency of diaspore removal and the higher removal distances observed in these sites. Finally, we experimentally evaluated if previous handling by birds (a condition more frequent in continuous forests) would affect ant attendance to fallen fruits. For this approach, we used as a model the bird-dispersed species Psychotria suterella (Rubiaceae), a common treelet in the understory of our forest sites. As expected, "feces-embedded" and "mandibulated" P. suterella fruits had increased frequencies of ant attendance than "intact" fruits. This result suggests that plant species in fragmented forests, together with the pervasive loss of their primary seed dispersers, may also be affected by the decreased attractiveness of unhandled fruits to ants (secondary dispersers), in spite of the abundance of these insects on the forest floor. Altogether, our results indicate that Atlantic Forest fragmentation negatively affects ant-diaspore interactions with respect to most of the studied parameters. Therefore, we expect that fragments will present a decrease on ant-derived potential benefits to seeds and seedlings
Doutorado
Ecologia
Doutor em Ecologia
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Marquitti, Flávia Maria Darcie. "Redes de interação entre morcegos frugívoros e plantas = variação geográfica e conservação de nicho." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316163.
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Orientador: Paulo Roberto Guimarães JúniorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Os mutualismos são interações importantes do ponto de vista ecológico e evolutivo, uma vez que influenciam a sobrevivência de diversos organismos, podendo determinar a organização da comunidade. Dada a importância ecológica e evolutiva das interações mutualísticas, é importante estudar quais fatores influenciam a sua organização. Como organismos aparentados compartilham características fenotípicas similares, é comum que espécies filogeneticamente próximas interajam com um conjunto de espécies similar, levando a um padrão conhecido por conservação filogenética do nicho. Apesar de este padrão ocorrer com frequencia, condições bióticas e abióticas locais podem levar à variação geográfica nas interações. A presença ou ausência de potenciais parceiros mutualísticos também podem alterar o padrão local de interações de uma espécie. Estudando interações entre morcegos frugívoros e plantas, investiguei como os padrões de interação de espécies em dez redes mutualísticas variavam conforme a distribuição geográfica. Nesse sentido, duas hipóteses principais guiaram este trabalho: a hipótese da conservação de nicho das interações e a hipótese da variação geográfica das interações. Caracterizei o padrão de interação das espécies de morcegos nas redes por meio de diferentes métricas usadas no estudo de redes ecológicas. Analisei a conservação de nicho das interações e a variação geográfica de espécies de morcego que ocorreram em um maior número de redes. Espécies filogeneticamente próximas não tenderam a apresentar padrões de interação mais parecidos entre si. Algumas das espécies mais frequentes apresentaram características dos padrões de interação em gradiente ou mosaico ao longo de sua distribuição geográfica. Estes resultados evidenciam que algumas características do padrão de interação de morcegos frugívoros, como grau de generalismo e o grau padronizado dentro do módulo são conservadas pela filogenia. No entanto algumas espécies apresentaram o grau de generalismo e o papel em relação aos módulos da rede variando ao longo da geografia, seguindo previsões da teoria do mosaico geográfico coevolutivo
Abstract: Mutualisms are important interactions to ecology and evolution because they affect the survivorship of many organisms and may shape community organization. Therefore, it is important to study which factors affect their organization. As related organisms share similar phenotypic traits, it is common that close phylogenetic species interact with a similar set of species, resulting in a pattern known as phylogenetic niche conservatism. Although this pattern frequently occurs, biotic and abiotic local conditions may lead to geographic variation of the interactions. The presence or absence of potential mutualistic partners may also change local interactions of a species. I studied interactions between frugivorous bats and plants and I investigated how species interactions patterns varied geographically across ten mutualistic networks. Two main hypotheses guided this work: the interaction niche conservatism hypothesis and the geographical variation hypothesis. I delineated the interaction patterns of bat species in the networks through different metrics used in ecological network studies. I analyzed the niche conservatism and geographical variation of bat species which occurred frequently in the networks. Related species did not tend to have similar patterns of interaction. Within their geographical range, some species vary markedly in their patterns of interaction and this variation often occurs as mosaics or, less frequently, as gradients. These results point out that some patterns of interaction of frugivorous bats, as the specialization degree and the standardized within-module degree, are conserved by phylogeny. However, some species showed variations through geography both in the specialization degree and in their role regarding the network modules, leading to a geographic mosaic of coevolution with potential implications to ecology and coevolution
Mestrado
Ecologia
Mestre em Ecologia
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Mayhew, Rebekah Jane Watts. "The species and functional composition of bird communities in regenerating tropical forests." Thesis, University of Stirling, 2017. http://hdl.handle.net/1893/27894.
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The widespread threat of species extinctions caused by the destruction and degradation of tropical primary forest (PF) could potentially be mitigated by the expansion of regenerating secondary forest (SF). However, the conservation value of SF remains controversial, and is dependent on many site- and landscape-scale factors, such as habitat age and isolation. The aim of this thesis was to assess the role that SF can play in conserving forest bird communities in central Panama. We study a chronosequence of SF aged 20 – 120-years-old, with sites either isolated from or connected to extensive PF. Our results suggest that SF supports high levels of avian species diversity, and similar community composition to PF. Whilst forest age plays a small role in determining compositional similarity to PF, connectivity to extensive PF was the main determinant of community composition. However, despite high species richness and complex community composition, some specialist PF bird species were consistently absent from SF, and isolated PF. The functional diversity of bird communities did not vary substantially across the forest age and isolation gradient, although we did find some inter-guild differences; with distinct responses in communities of avian insectivores and frugivores. Isolation caused shifts in the trophic traits of insectivores, but resulted in alterations in the dispersal traits of frugivores. The response of bird and tree community composition to forest age and isolation was similar, although isolation had a stronger impact on bird communities. Bird diversity and composition tracked changes in forest structure over succession. When examining the role of birds in seed-dispersal networks, we found bird gape width was the key predictor of seed size consumed. Large-gaped birds consume a wider variety of seed-sizes than small-gaped birds, and small-seeded trees attract a greater number of bird species than large-seeded trees. These results imply high levels of redundancy among small-gaped avian frugivores and small-seeded plant species, but low levels of redundancy among large-seeded plant species and their avian dispersers. This suggests that large-seeded plants may be most at risk of dispersal failure following any change in avian frugivore assemblages. Together, these results suggest that SF can play a key role in sustaining most tropical biodiversity, and in maintaining ecosystem services. Our findings emphasise the importance of integrating SF into conservation strategies to support and buffer tropical PF habitats.
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Valentim, Daniel Costa. ""Semear à preciso, viver nÃo à preciso": economia do compartilhamento e dispersÃo de sementes digitais atravÃs de redes P2P." Universidade Federal do CearÃ, 2017. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=19503.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorA presente tese versa sobre compartilhamento de arquivos na era da internet. Analisaremos aspectos da socialidade em uma comunidade online especializada na arte do cultivo, semeio, preservaÃÃo e disseminaÃÃo de arquivos digitais (compreendidos enquanto âsementes digitaisâ). As sementes digitais sÃo basicamente qualquer arquivo de computador digitalizado (por exemplo, um filme, uma mÃsica, um livro, um software etc.) que necessita ser semeado virtualmente atà que floresÃa e possa ser compartilhado atravÃs da internet via redes P2P (peer-to-peer). Nesse sentido, esta tese à uma narrativa sobre uma experiÃncia relacional que vivenciamos (de 2008 a 2017) em uma comunidade de âcyberagricultoresâ denominada OÃsis (nome fictÃcio). O OÃsis à uma comunidade fechada que possui cerca de 60 mil membros registrados (atà inÃcio de 2017). Nossa perspectiva metodolÃgica nos levou a seguir linhas errÃticas dos traÃados digitais que compÃem as dinÃmicas singulares que constituem aquilo que denominamos de âeconomia do compartilhamentoâ. Deste modo, tentamos elucidar o movimento das sementes digitais atravÃs dos sensos de moralidades creditados pelos âsemeadores de arquivosâ que frequentam esta comunidade em particular. Com efeito, relatamos nesta tese prÃticas e vivÃncias que compÃem aquilo que identificamos como âÃtica do compartilharâ, espÃcie de âespÃrito do compartilhamentoâ que atua (atravÃs de uma alquimia simbÃlica) na transformaÃÃo de arquivos ou mercadorias digitais em presentes, dÃdivas e honrarias prontas para serem dispersadas atravÃs de redes cooperativas e descentralizadas de compartilhamento. Dito de outro modo, uma semente digital pode ser melhor apresentada sob a forma de uma âcoisa vivaâ, isto Ã, como uma semente de vida carregada de riquezas, dignidades e esperanÃas, exatamente por estabelecer o entendimento de que produÃÃes culturais sÃo artefatos produzidos para serem dispersados livremente como um âbem comumâ. Por fim, ressaltamos de que forma esta cyberecologia se apresenta como um projeto que pretende garantir a implantaÃÃo de uma rede de proteÃÃo de sementes digitais ameaÃadas pelo esquecimento e pelo descaso.
The present thesis deals with file sharing in the age of the Internet. We will analyze aspects of sociality in a file sharing community specialized in the art of cultivating, sowing, preserving of digital files (described as âdigital seedsâ). Digital seeds are basically any digitized computer file (for example, a movie, a song, a book, a software etc.) that needs to be virtually planted until it blooms and can be shared over the internet by P2P (peer-to-peer) networks. In this sense, this thesis is a narrative about a relational experience that we experienced (from 2008 to 2017) in a community of cyber seeders named Oasis (fictitious name). Oasis is a closed community that has about 60,000 registered members (until early 2017). Our methodological perspective led us to follow erratic digital paths that make up the unique dynamic that constitutes what we call "sharing economy". In this way, we try to elucidate the movement of digital seeds through the senses of morality credited by the "file sharers" who particularly attend that community. Indeed, in this thesis we report practices and experiences that make up what we identify as "ethics of sharing", a sort of "spirit of sharing" that acts (through a symbolic alchemy) in the transformation of digital files or goods into gifts and honors ready to be dispersed through cooperative and decentralized sharing networks. In other words, a digital seed can best be presented in the form of a "living thing"; that is, as a seed of life laden with riches, dignities and hopes, exactly for establishing the understanding that cultural productions are artifacts produced to be freely dispersed as a "common good." Finally, we highlight how this cyber ecology presents itself as a project that intends to ensure the implementation of a protection network of digital seeds threatened by forgetfulness and neglect.
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Mendes, Filipa dos Santos. "The impact of introduced animals and plants on São Tomé seed-dispersal network." Master's thesis, 2017. http://hdl.handle.net/10316/82870.
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Dissertação de Mestrado em Ecologia apresentada à Faculdade de Ciências e TecnologiaAs invasões biológicas são um dos principais impulsionadores da perda de biodiversidade em todo o mundo, sendo particularmente perturbadora para as ilhas oceânicas. Essas extinções de espécies implicam a perda de funções do ecossistema, como a dispersão de sementes por animais. Trabalhando no hotspot de endemicidade da ilha de São Tomé, utilizamos análises complexas de rede de última geração para avaliar o impacto de grandes dispersores introduzidos nas redes de dispersão de sementes, formadas por pequenos dispersores endêmicos. As comunidades insulares evoluíram sob baixa pressão seletiva de grandes vertebrados, filtrados pela barreira oceânica para a dispersão. Portanto, a integração de grandes dispersores em São Tomé é susceptível de ter grandes implicações para a dispersão de plantas nativas e introduzidas, modelando o recrutamento de plantas e o futuro das florestas nativas.Durante um ano, compilámos interações entre plantas e os dispersores das suas sementes, através de cinco métodos complementares de amostragem: observações diretas, revisão literária, questionários, análise de excrementos e conteúdos estomacais. Após a reconstrução da rede de dispersão, avaliámos se a origem dos dispersores (nativos vs. introduzidos) ou a largura da sua garganta afeta o seu papel enquanto dispersores de sementes, nomeadamente: número de plantas dispersadas, grau de seletividade (d'), “species strenght” e tamanho das sementes dispersadas. A rede de São Tomé revelou 419 interações entre 22 espécies de dispersores (12 aves, 2 morcegos, 1 cobra e 7 mamíferos não voadores) e 150 espécies de plantas. Duas das plantas mais frequentemente dispersadas, Cecropia peltata e Rubus rosifolius são espécies altamente invasoras. Cada método de amostragem revelou-se principalmente útil para um pequeno grupo de dispersores, fornecendo por isso informação altamente complementar. Os questionários provaram ser o método de amostragem que contribuiu com mais interações, seguido da análise de excrementos e de conteúdos estomacais. Os dispersores nativos e introduzidos não diferiram significativamente em nenhum dos três descritores topológicos analisados, no entanto os dispersores introduzidos tenderam a dispersar espécies com sementes maiores. Esta diferença deve-se especificamente à maior largura da garganta dos dispersores introduzidos. No seu conjunto, estes resultados apontam para um importante potencial perturbador dos dispersores introduzidos, ao alterarem a pressão seletiva em favor de espécies com sementes grandes. Estas diferenças no tamanho das sementes dispersadas não se refletiu contudo em diferenças na topologia das interações estabelecidas, alertando para a necessidade de considerar simultaneamente características biológicas na interpretação das redes de interações.
Biological invasions are a key driver of biodiversity loss worldwide being particularly disruptive on oceanic islands. Such species extinctions entail the loss of ecosystem functions such as seed dispersal by animals. Working in the endemicity hotspot of São Tomé Island, we used state-of-the art complex network analysis to evaluate the impact of large introduced dispersers on seed-dispersal networks formed by small endemic dispersers. Island communities have evolved under low selective pressure from large vertebrates, filtered by the oceanic barrier to dispersal. Therefore, the integration of large dispersers into São Tomé is likely to have large implications for the dispersal of native and introduced plants, shaping plant recruitment and the future of the native forests. During one year, we compiled interactions between plants and seed dispersers through five complementary sampling methods: direct observations, literary review, questionnaires, excrement analysis and stomach contents. After rebuilding the dispersion network, we evaluated whether the origin of the dispersers (natives vs. introduced) or the width of their throat affects their role as seed dispersers, namely: number of plants dispersed, degree of selectivity (d '), "Species strength" and seed size dispersed. The São Tomé network revealed 419 interactions between 22 dispersers species (12 birds, 2 bats, 1 snake and 7 non-flying mammals) and 150 plant species. Two of the most frequently dispersed plants, Cecropia peltata and Rubus rosifolius are highly invasive species. Each sampling method proved to be particularly informative for a small group of dispersers, and therefore their results are largely complementary. The questionnaires proved to be the sampling method that contributed with more interactions, followed by fecal and stomach content analysis. Native and introduced dispersers did not differ significantly in any of the three topological descriptors analyzed, however introduced dispersers tended to disperse species with larger seeds. This difference is largely explained by the larger gape width of the introduced dispersers. Altogether, these results point to an important disruptive potential of introduced dispersers, by altering the selective pressure in favor of species with larger seeds. However, these differences in the size of the dispersed seeds were not reflected in differences in the topological patterns of the interactions, highlighting the need to simultaneously consider biological traits while interpreting interactions networks.
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Marthy, William. "Scale- and trait dependent responses of bird communties to lowland rainforest restoration and frugivore-bird-seed interaction networks in Sumatra, Indonesia." Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5E1E-F.
Full textBooks on the topic "Seed dispersal network"
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Lopes, Dominic McIver. Beings for Beauty. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198827214.003.0002.
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The main argument for the network theory of aesthetic value is that it better explains the facts about aesthetic activity than does its rival, aesthetic hedonism. Aesthetic activity is not limited to appreciation, and six case studies are presented of aesthetic agents whose expertise covers a range of aesthetic activities. From a survey of the case studies, we see that six facts need explaining. Aesthetic experts disperse into almost all demographic niches, they jointly inhabit the whole aesthetic universe, they specialize by aesthetic domain, they specialize by type of activity, they specialize by activity and domain interact, and their expertise is rooted in relatively stable psychological traits.
Book chapters on the topic "Seed dispersal network"
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da Silva, Fernanda Ribeiro, and Marco Aurélio Pizo. "Restoration of seed dispersal interactions in communities invaded by non-native plants." In Plant invasions: the role of biotic interactions, 391–401. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0391.
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Abstract Restoration aims to rebuild not only species but also the tangled interactions between species that ensure communities perpetuate by themselves. In tropical forests, restoration of seed dispersal interactions is essential because most plant species depend on animals to spread their seeds. A big challenge in restoring such forests is dealing with invasion by non-native species. Non-native plant species may outcompete and eliminate native species from the community, potentially disrupting or arresting the restoration process. Once established, invasive non-native plants are usually incorporated into the local seed dispersal network, potentially causing loss of biodiversity by competition with native species. This chapter reports on a case study of a 25-year old restored forest invaded by several bird-dispersed plant species. We assessed network metrics at the species level to specifically evaluate the role performed by invasive non-native species in the structure of the bird - seed dispersal network. The removal of invasive non-native plants and the re-establishment of native plant communities should be considered for the restoration of habitats invaded by non-native plants. For this reason, we discuss the impacts of removing such non-native plants and explore the consequences for the structure of the overall network. Because restoration areas are open systems, even after the removal of invasive non-native plant species they can return via seed dispersal. So, both the control and management of invasive non-native species would be more effective if planned with a landscape perspective. We also point out relevant management aspects to avoid the negative influence of invasive non-native plants on the seed dispersal interactions occurring between native plant and bird species in restored tropical forests.
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Emer, Carine, and Sérgio Timóteo. "How a network approach has advanced the field of plant invasion ecology." In Plant invasions: the role of biotic interactions, 324–39. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0324.
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Abstract Every organism on Earth, whether in natural or anthropogenic environments, is connected to a complex web of life, the famous 'entangled bank' coined by Darwin in 1859. Non-native species can integrate into local 'banks' by establishing novel associations with the resident species. In that context, network ecology has been an important tool to study the interactions of non-native species and the effects on recipient communities due to its ability to simultaneously investigate the assembly and disassembly of species interactions as well as their functional roles. Its visually appealing tools and relatively simple metrics gained momentum among scientists and are increasingly applied in different areas of ecology, from the more theoretical grounds to applied research on restoration and conservation. A network approach helps us to understand how plant invasions may or may not form novel species associations, how they change the structure of invaded communities, the outcomes for ecosystem functionality and, ultimately, the implications for the conservation of ecological interactions. Networks have been widely used on pollination studies, especially from temperate zones, unveiling their nested patterns and the mechanisms by which non-native plants integrate into local communities. Yet, very few papers have used network approaches to assess plant invasion effects in other systems such as plant-herbivore, plant-pathogen or seed-dispersal processes. Here we describe how joining network ecology with plant invasion biology started and how it has developed over the last few decades. We show the extent of its contribution, despite contradictory results and biases, to a better understanding of the role of non-native plant species in shaping community structure. Finally, we explore how it can be further improved to answer emerging questions.
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Escribano-Avila, Gema, Carlos Lara-Romero, Ruben Heleno, and Anna Traveset. "Tropical Seed Dispersal Networks: Emerging Patterns, Biases, and Keystone Species Traits." In Ecological Networks in the Tropics, 93–110. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-68228-0_7.
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Heleno, Ruben H. "The effect of non-native plant invasions on the dispersal of native seeds." In Plant invasions: the role of biotic interactions, 256–69. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0256.
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Abstract Non-native plants change the communities they integrate in multiple ways, including direct and indirect effects on co-occurring native vegetation. While direct effects are more obvious, indirect effects, i.e. those mediated by biotic interactions with other trophic levels, can also have pervasive consequences for long-term community persistence. Seed dispersal is a critical stage during the life cycle of most plants, as it lays the foundations for plant recruitment patterns and long-term vegetation dynamics. By interacting with seed-dispersing animals, primarily frugivorous birds and mammals, plants can positively or negatively affect the dispersal of co-occurring native seeds. In an increasingly invaded world, it is thus critically important to identify general trends on the direction and magnitude of these effects. This chapter reviews the empirical evidence supporting such changes and the potential underlying mechanisms driving them. While the direct impacts of plant invasions are relatively easy to document, indirect effects are much harder to detect. Nevertheless, the most important consequence of the incorporation of new fruiting plants into native communities seems to be a direct competition for the services provided by the local dispersers, negatively affecting native seed dispersal rates. However, another key message emerging from the literature is that responses are highly idiosyncratic, and usually habitat- and species-specific, and therefore resistant to broad generalizations. Fruiting phenology, and in particular the synchrony/asynchrony between the availability of native and non-native fruits, seems to be a particularly important driver of the direction of the responses (i.e. towards facilitation or competition). However, most evidence is still derived from anecdotal observations and formal community level assessments are largely missing. Similarly, how invasive plants change the emergent structure of seed dispersal networks remains uncertain, with early evidence suggesting that novel seed dispersal networks might be structurally very similar to native ones. Bringing together classic experimental designs and new technical and analytical tools to provide broad synthesis will be vital in the near future to clarify the direction, magnitude and generality of these effects.
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Ribeiro da Silva, Fernanda, and Marco Aurélio Pizo. "Restoration of seed dispersal interactions in communities invaded by non-native plants." In Plant invasions: the role of biotic interactions, 391–401. CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0022.
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Restoration aims to rebuild not only species but also the tangled interactions between species that ensure communities perpetuate by themselves. In tropical forests, restoration of seed dispersal interactions is essential because most plant species depend on animals to spread their seeds. A big challenge in restoring such forests is dealing with invasion by non-native species. Non-native plant species may outcompete and eliminate native species from the community, potentially disrupting or arresting the restoration process. Once established, invasive non-native plants are usually incorporated into the local seed dispersal network, potentially causing loss of biodiversity by competition with native species. This chapter reports on a case study of a 25-year old restored forest invaded by several bird-dispersed plant species. We assessed network metrics at the species level to specifically evaluate the role performed by invasive non-native species in the structure of the bird - seed dispersal network. The removal of invasive non-native plants and the re-establishment of native plant communities should be considered for the restoration of habitats invaded by non-native plants. For this reason, we discuss the impacts of removing such non-native plants and explore the consequences for the structure of the overall network. Because restoration areas are open systems, even after the removal of invasive non-native plant species they can return via seed dispersal. So, both the control and management of invasive non-native species would be more effective if planned with a landscape perspective. We also point out relevant management aspects to avoid the negative influence of invasive non-native plants on the seed dispersal interactions occurring between native plant and bird species in restored tropical forests.
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Emer, Carine, and Sérgio Timóteo. "How a network approach has advanced the field of plant invasion ecology." In Plant invasions: the role of biotic interactions, 324–39. CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0018.
Full textAbstract:
Every organism on Earth, whether in natural or anthropogenic environments, is connected to a complex web of life, the famous 'entangled bank' coined by Darwin in 1859. Non-native species can integrate into local 'banks' by establishing novel associations with the resident species. In that context, network ecology has been an important tool to study the interactions of non-native species and the effects on recipient communities due to its ability to simultaneously investigate the assembly and disassembly of species interactions as well as their functional roles. Its visually appealing tools and relatively simple metrics gained momentum among scientists and are increasingly applied in different areas of ecology, from the more theoretical grounds to applied research on restoration and conservation. A network approach helps us to understand how plant invasions may or may not form novel species associations, how they change the structure of invaded communities, the outcomes for ecosystem functionality and, ultimately, the implications for the conservation of ecological interactions. Networks have been widely used on pollination studies, especially from temperate zones, unveiling their nested patterns and the mechanisms by which non-native plants integrate into local communities. Yet, very few papers have used network approaches to assess plant invasion effects in other systems such as plant-herbivore, plant-pathogen or seed-dispersal processes. Here we describe how joining network ecology with plant invasion biology started and how it has developed over the last few decades. We show the extent of its contribution, despite contradictory results and biases, to a better understanding of the role of non-native plant species in shaping community structure. Finally, we explore how it can be further improved to answer emerging questions.
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Heleno, Ruben H. "The effect of non-native plant invasions on the dispersal of native seeds." In Plant invasions: the role of biotic interactions, 256–69. CABI, 2020. http://dx.doi.org/10.1079/9781789242171.0014.
Full textAbstract:
Non-native plants change the communities they integrate in multiple ways, including direct and indirect effects on co-occurring native vegetation. While direct effects are more obvious, indirect effects, i.e. those mediated by biotic interactions with other trophic levels, can also have pervasive consequences for long-term community persistence. Seed dispersal is a critical stage during the life cycle of most plants, as it lays the foundations for plant recruitment patterns and long-term vegetation dynamics. By interacting with seed-dispersing animals, primarily frugivorous birds and mammals, plants can positively or negatively affect the dispersal of co-occurring native seeds. In an increasingly invaded world, it is thus critically important to identify general trends on the direction and magnitude of these effects. This chapter reviews the empirical evidence supporting such changes and the potential underlying mechanisms driving them. While the direct impacts of plant invasions are relatively easy to document, indirect effects are much harder to detect. Nevertheless, the most important consequence of the incorporation of new fruiting plants into native communities seems to be a direct competition for the services provided by the local dispersers, negatively affecting native seed dispersal rates. However, another key message emerging from the literature is that responses are highly idiosyncratic, and usually habitat- and species-specific, and therefore resistant to broad generalizations. Fruiting phenology, and in particular the synchrony/asynchrony between the availability of native and non-native fruits, seems to be a particularly important driver of the direction of the responses (i.e. towards facilitation or competition). However, most evidence is still derived from anecdotal observations and formal community level assessments are largely missing. Similarly, how invasive plants change the emergent structure of seed dispersal networks remains uncertain, with early evidence suggesting that novel seed dispersal networks might be structurally very similar to native ones. Bringing together classic experimental designs and new technical and analytical tools to provide broad synthesis will be vital in the near future to clarify the direction, magnitude and generality of these effects.
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Hughes, Kit. "To Extend Vision Beyond the Horizon, to See the Unseen: Industrial Television in the Post-War Era." In Television at Work, 62–92. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190855789.003.0003.
Full textAbstract:
“Industrial television” (closed-circuit television referred to as ITV) was the first initiative to recognize the potential of television tailored specifically to the needs of industry. This chapter shows how ITV was positioned as a mechanism to extend bodies, adapting workers to match increased physical demands of post-war (1940s–1950s) industrial and informational architectures. ITV as prosthesis made working bodies stronger, bigger, and more tightly bound into automated information systems. Faster than a speeding assembly line, more powerful than a six-story furnace, able to retrieve dispersed data with a single command, these supermen appealed to industries seeking production and workforce efficiencies. In the mediated office, television transformed humans into nodes within complex human-machine hybrid information networks that anticipated networked computing. This chapter (keyword: flow) contributes to studies of how “work systems” produce people, socializing them to the conditions and expectations of capitalism.
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Hollings, Ken. "‘The Very Form of Perverse Artificial Societies’: The Unstable Emergence of the Network Family from its Cold War Nuclear Bunker." In Cold War Legacies. Edinburgh University Press, 2016. http://dx.doi.org/10.3366/edinburgh/9781474409483.003.0009.
Full textAbstract:
Deleuze and Guattari's ‘perverse artificial societies’ were the random ones thrown up by Paris’s unstable telephone system in the 1960s and 1970s, where crossed lines, misdialed numbers and bad connections created an entire phantom network of voices: ‘a society of unknowns’. Just as the ‘nuclear family’ was seen as a strategic element in the Cold War, dispersed into suburban enclaves of self-contained domestic units, so the ‘network family’ of today, distributed across social media now finds itself being defined as a strategic element in a warring online cyber community: its elusive and fragmented presence regarded as both a threat and a defence position. What this shift reveals is that the nuclear family was not as stable as it seemed and that the networked family is more tightly defined and structured according to what is perceived to exist outside of it. From this perspective it is easier to understand today’s panics over online security and ‘whistle blowers’ against state intervention in private communication, who are frequently presented by the mainstream media as domestically unstable – the chapter ends with a discussion Edward Snowden, Bradley/Chelsea Manning, and Julian Assange, together with the psychosexually aggressive language and imagery of Anonymous.
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McLoughlin, Catherine, and Mark J. W. Lee. "Pedagogical Responses to Social Software in Universities." In Social Computing, 417–38. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-60566-984-7.ch029.
Full textAbstract:
Learning management systems (LMS’s) that cater for geographically dispersed learners have been widely available for a number of years, but many higher education institutions are discovering that new models of teaching and learning are required to meet the needs of a generation of learners who seek greater autonomy, connectivity, and socioexperiential learning. The advent of Web 2.0, with its expanded potential for generativity and connectivity, propels pedagogical change and opens up the debate on how people conceptualize the dynamics of student learning. This chapter explores how such disruptive forces, fuelled by the affordances of social software tools, are challenging and redefining scholarship and pedagogy, and the accompanying need for learners to develop advanced digital literacy skills in preparation for work and life in the networked society. In response to these challenges, the authors propose a pedagogical framework, Pedagogy 2.0, which addresses the themes of participation in networked communities of learning, personalization of the learning experience, and learner productivity in the form of knowledge building and creativity.
Conference papers on the topic "Seed dispersal network"
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Diwakar, Philip, Vibhor Mehrotra, and Franklin Richardson. "Mitigation of Bending Stress and Failure Due to Temperature Differentials in Piping Systems Carrying Multiphase Fluids: Using CFD and FEA." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79969.
Full textAbstract:
The bending of large pipes due to temperature differentials between the bottom and top of the pipe is a very serious problem. The temperature differentials can either be caused by extremely cold liquids (such as methane or ethylene flowing from a lateral into a flare header) or hot liquids flowing at the bottom of a piping system (such as in a Vacuum transfer line) while the top is exposed to atmospheric conditions. In some cases liquids may be produced by Joule-Thompson cooling of high pressure cold gas as it expands through a safety-relief or emergency depressurization valve. The liquid so formed can accumulate, for example, on the dead leg side of a flare header. The differential expansion can deform the pipe so that it lifts off its supports. It takes a finite amount of time for the heat transfer by conduction to equilibrate the temperature to a more benign level. The initial stresses induced due to large thermal differential may even cause the pipe to crack in the region of the supports and T-joints to the laterals. This phenomenon has been observed in several industries, most predominantly in the petrochemical industry. This paper recounts the use of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to study this important phenomenon. The liquid flowing from the lateral into the main header pipe is multiphase in the dispersed, stratified, slug or annular flow re´gime. Multiphase flows with heat transfer are analyzed using CFD. The temperatures on the walls of the pipe system are then transferred to the FEA and analyzed for heat transfer and thermal stresses. These stresses are compared to ASME standards to see if they are within allowable limits. This paper also recounts efforts to reduce the bending effect by preventing liquid accumulation on the dead leg side. Other methods that provide better supports for bent piping are studied. Further, methods of equilibrating the temperature faster to prevent the bowing of the pipe are also studied. It is hoped that this presentation will benefit people designing piping networks with varying liquid and vapor traffic by providing a safe environment free of cracks and spills.
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Diwakar, Philip, Vibhor Mehrotra, and Frank Richardson. "Mitigation of Bending Stress and Failure Due to Temperature Differentials in Piping Systems Carrying Multiphase Fluids: Using CFD and FEA." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72463.
Full textAbstract:
The bending of large pipes due to temperature differentials between the bottom and top of the pipe is a very serious problem. The temperature differentials can either be caused by extremely cold liquids (such as methane or ethylene flowing from a lateral into a flare header) or hot liquids flowing at the bottom of a piping system (such as in a Vacuum transfer line) while the top is exposed to atmospheric conditions. In some cases liquids may be produced by Joule-Thompson cooling of high pressure cold gas as it expands through a safety-relief or emergency depressurization valve. The liquid so formed can accumulate, for example, on the dead leg side of a flare header. The differential expansion can deform the pipe so that it lifts off its supports. It takes a finite amount of time for the heat transfer by conduction to equilibrate the temperature to a more benign level. The initial stresses induced due to large thermal differential may even cause the pipe to crack in the region of the supports and T-joints to the laterals. This phenomenon has been observed in several industries, most predominantly in the petrochemical industry. This paper recounts the use of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to study this important phenomenon. The liquid flowing from the lateral into the main header pipe is multiphase in the dispersed, stratified, slug or annular flow re´gime. Multiphase flows with heat transfer are analyzed using CFD. The temperatures on the walls of the pipe system are then transferred to the FEA and analyzed for heat transfer and thermal stresses. These stresses are compared to ASME standards to see if they are within allowable limits. This paper also recounts efforts to reduce the bending effect by preventing liquid accumulation on the dead leg side. Other methods that provide better supports for bent piping are studied. Further, methods of equilibrating the temperature faster to prevent the bowing of the pipe are also studied. It is hoped that this presentation will benefit people designing piping networks with varying liquid and vapor traffic.