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1
Ho, Wai-hoong. "The taxonomy and ecology of land snails in Hong Kong, with particular reference to factors affecting their distribution and population dynamics /." Hong Kong : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20667012.
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Babiker, Ismail Elsheikh. "Evaluation of various biomanipulations aimed at controlling freshwater pulmonate snails." Thesis, University of Sussex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332587.
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Ho, Wai-hoong, and 何慧紅. "The taxonomy and ecology of land snails in Hong Kong, with particular reference to factors affecting their distribution and populationdynamics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31211458.
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Lee, Jacqueline S. "The distribution and ecology of the freshwater molluscs of northern British Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/MQ62481.pdf.
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Daldorph, Peter W. G. "The role of short chain carboxylic acids in the ecology of freshwater snails." Thesis, University of Sussex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.568229.
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Snider, Sunny Brooke. "Towards a movement ecology: modeling the behavioral response of invasive snails to resources and competition." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-11052007-171057/.
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The movement of individuals is one of the fundamental components of contemporary ecological problems such as metapopulation theory, epidemic models, competitive coexistence, and invasion dynamics. Advection-diffusion models, sometimes with a reaction term, have been usefully applied to such problems. For this dissertation, I broadened this approach by seeking to understand the effects of certain biotic and abiotic factors on movement ecology, and asking how to incorporate flexible behavioral responses into classical advection-diffusion models. I asked how resources, competitive environment, and habitat structure, interacting with body size or not, affect the movement behaviors of two coexisting invasive snails (Melanoides tuberculata and Tarebia granifera), and whether including the behavioral response to these factors improves advection-diffusion models of movement. I also made natural history observations regarding the snail system to provide a biological context for my empirical work. To address these questions, I conducted replicated experiments and observational studies, extended advection-diffusion models, and arbitrated among candidate models using AIC (Akaike?s Information Criterion) model selection. Specific studies included (1) behavioral response to phenotypic and resource heterogeneities, and their interaction, (2) behavioral response to intraspecific and interspecific competition, and (3) behavioral response to spatially uniform versus spatially heterogeneous environments. In summary, this dissertation provides insights into modeling movement behaviors, using two coexisting invasive snails as the model system. I advocate for a behaviorally informed modeling framework that integrates sentient responses of individuals in terms of movement, improving our ability to accurately model ecological processes that depend on movement ecology.
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Coppolino, Marla Lee. "LAND SNAIL ABUNDANCE AND DIVERSITY WITH ASSOCIATED ECOLOGICAL VARIABLES IN SIX SOUTHERN ILLINOIS COUNTIES." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/43.
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Various ecological parameters, including soil pH, calcium, and habitat complexity have been suggested in the literature as having influence on land snail abundance and diversity. I compared relationships between 15 ecological parameters and snail abundance and diversity. 5,393 snails of 72 species were collected from 60 sites in 2007. Habitat observations were recorded in the field and soil core samples taken at each site and later analyzed for soil moisture, organic matter, cation exchange capacity, pH, calcium, magnesium, zinc, potassium, phosphorus, sulfur, boron, manganese, iron and copper. Statistical analyses were run using these soil factors plus a habitat complexity index (from combined values assigned to different levels of vegetation, topography and exposed rock), for a total of 15 parameters. To reduce the number of parameters and arrive at a more biologically meaningful model, Bayesian Information Criteria analysis (BIC) was run for abundance and diversity. The resulting best-fitted BIC model for abundance contained 3 parameters (pH, S, and habitat complexity) (R2 = 0.47), all of which were positively associated with abundance in a multiple regression analysis. For diversity, the best-fitted BIC model also contained 3 parameters (Ca, Fe, and habitat complexity) (R2 = 0.54). Ca and habitat complexity showed a positive association in the multiple regression analysis, but Fe was inversely associated with diversity, suggesting Fe could potentially act as an ecological limiting factor to it. These results suggest that land snail abundance and diversity are best treated separately in analyses, as they are influenced by different variables, with the exception of habitat complexity, which is suggested to have a positive association with both abundance and diversity. The regression model equations have potential value in that they can be used to predict snail abundance and diversity in areas that have not been assessed.
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Reilly, Stephanie A. "Forecasting the Spread and Invasive Potential of Apple Snails (Pomacea spp.) in Florida." NSUWorks, 2017. http://nsuworks.nova.edu/occ_stuetd/460.
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Forecasting the potential range of invasive species is a critical component for risk assessment, monitoring, and management. However, many of these invasive species are not yet at equilibrium which can be problematic for many modelling approaches. Using the climate matching method, MaxEnt, a series of species distribution models (SDMs) and risk analysis maps were created for select apple snail species in Florida: Pomacea canaliculata, P. diffusa, and P. maculata. Apple snails, freshwater gastropods in the family Ampullariidae, are native to South America and were introduced to the United States via the pet trade approximately 40 years ago. These highly invasive species have already been introduced in ten states and established in at least seven. The models and risk analysis in this study show the majority of Florida was at least moderately suitable for all apple snails modeled, with P. maculata posing the greatest threat.
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Przeslawski, Rachel. "Sunburnt sea snails the role of ultravoilet radiation in the development of encapsulated embryos from temperate rocky shores /." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060221.093951/index.html.
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Gillilland, Merritt Gale. "Dispersal ecology and control of the invasive land snail Cepaea nemoralis (L. 1758), from Ingham County, Michigan." Diss., Connect to online resource - MSU authorized users, 2006.
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Thesis (Ph. D.)--Michigan State University. Dept. of Zoology. Program in Ecology, Evolutionary Biology and Behavior, 2006.<br>Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 161-168). Also issued in print.
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Hutchings, Jack A. "No Honor Among Snails: Conspecific Competition Leads to Incomplete Drill Holes in the Naticid Gastropod Neverita delessertiana (R cluz)." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4336.
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The fossil record of drilling predation has been widely used to study predator-prey interactions and their relative importance on long-term evolutionary processes. Incomplete drill holes have been interpreted as indicators of failed attacks due to well-defended prey. However, this interpretation is based on pair-wise interactions between one predator and one prey, a condition commonly compromised in nature. The hypothesis that interference among drilling predators leads to an increase in the relative frequency of incomplete drill holes was tested in the laboratory using the naticid Neverita delessertiana (R cluz) and a common prey, the bivalve Chione elevata (Say). The experiment consisted of an isolation treatment, where predators fed alone, and a competition treatment, where predators fed in groups of three. Predators in competition were grouped into two size cohorts, small and large. All drilling attacks made by isolated predators of both size groups were successful, resulting in complete drill holes, whereas, in competition, the incomplete drilling frequencies were 6.9% for the small predator group and 21.3% for the large predator group. A range of competitive, predator-predator interactions were observed, including grappling, prey theft, and cannibalism. These results suggest that interpretations of both field and fossil data must consider the role of competitive disruption as an additional source of incomplete drill holes. The implications of other observations, including prey 'suffocation' and the resumption of incomplete drill holes after successful prey theft, are also discussed.
12
Carne, Vanessa L. "Ecology of Mediterranean snails in Southern Australian agriculture : a study of Cernuella virgata and Cochlicella acuta on the Yorke Peninsula /." Title page, table of contents and summary only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phc2891.pdf.
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Havenhand, Jonathan Neil. "The physiological ecology and life history strategies of the nudibranch molluscs 'Adalaria proxima' (Alder & Hancock) and 'Onchidoris muricata' (Müller) (Gastropoda: Opisthobranchia)." Thesis, University of St Andrews, 1987. http://hdl.handle.net/10023/2708.
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This study investigated the physiological ecology, larval biology and population genetics of the nudibranch molluscs Adalaria proxima (A & H) and Onchidoris muricata (Müller). These two species are annual, simultaneous hermaphrodites and are ecologically very similar with the exception that A. proxima reproduces by means of pelagic lecithotrophic larvae whereas Omuricata has long-term planktotrophic larvae. The aim of the study was therefore to determine the selective pressures which resulted in the evolution of different larval types in these two species, and to ascertain the ecological and population genetic consequences thereof. Simple energy budgets comprising the major components (consumption, growth, respiration and reproduction) were constructed for laboratory populations of each species. In both A. proxima and O. muricata, feeding rate displayed an asymptotic increase with body size. Mean feeding rates of A. proxima were greater than those of comparable O. muricata individuals, and overall assimilation efficiency was higher in A. proxima than in O. muricata. This difference was reflected in the somatic growth rates which were correspondingly greater in A. proxima than in O. muricata. Net growth efficiencies were broadly comparable between the two species, however, growth of A. proxima was approximately linear over' time whilst that of O. muricata displayed a curvilinear, almost exponential, pattern. This is interpreted as demonstrating that some form of constraint (possibly feeding rate) operated on the growth rates of A. proxima but not on those of O. muricata. Respiration rates were found to be relatively constant within given animals, but significant differences were found between individuals. The allometry of respiration rate was not constant; Omuricata demonstrated a more rapid increase in respiration rate with increasing body size than did A. proxima. Individual variations in respiration rate did not reflect variations in the energy partitioned to either growth or reproduction. Reproductive patterns in the two species were dissimilar. A. proxima laid fewer spawn masses containing fewer, larger ova than those laid by O. muricata individuals. In addition, the spawning period of A. proxima was shorter than that of O. muricata (60 days and 105 days respectively). Both species exhibited a similar (proportional) degree of somatic catabolism over these periods. The consequently more rapid "degrowth" of A. proxima is interpreted as the necessary utilization of an energy resource (i. e. the soma) caused by an inability to meet the energy demands of reproduction through feeding alone. This was not the case in Oanuricata individuals which exhibited a much smaller maximum body size and were able to feed at a sufficiently rapid rate to maintain reproduction. In the latter case, the longer reproductive period served to maximise the total reproductive output. Several different measures of "Reproductive Effort" (RE) were calculated. These generally indicated that the RE of Omuricata was considerably greater than that of A. proxima. Although such differences have been used in the literature to classify the respective costs of different larval types or "reproductive strategies", the variability of the RE's obtained from the different measures used here has led to the suggestion that the general lack of association between RE and reproductive strategy which has been reported elsewhere may (partially) be attributable to the different measures of RE employed in different studies. Studies of the embryonic and larval period showed that the egg-to-juvenile period of O. muricata was approximately 50% longer than that of A. proxima. This difference was primarily attributable to the extended pelagic development of O. muricata larvae. Estimates of the degree of dispersal, and hence gene-flow, between populations of these species were tested by investigating the biochemical genetics of such populations. No data were available for O. muricata, but A. proxima populations proved to be more genetically heterogeneous than had been expected. It is therefore concluded that actual pelagic dispersal may be considerably abbreviated over that expected on the basis of larval culture data alone. A model is developed to explain the possible consequences of different egg-to-juvenile periods (which accrue from different larval types) on both the ecology of the benthic adult, and on overall energy partitioning to reproduction. However, although (probable) proximate causes and effects of the different reproductive traits exhibited by A. proxima and Oanuricata are shown, it has not been possible to determine the exact selective pressures which caused A. proxima to diverge from the ancestral "O. muricata" stock through the evolution of a pelagic lecithotrophic larva.
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Selbach, Christian [Verfasser], and Bernd [Akademischer Betreuer] Sures. "Biology and ecology of trematodes parasitizing aquatic snails in the Ruhr reservoir system in Germany / Christian Selbach. Betreuer: Bernd Sures." Duisburg, 2016. http://d-nb.info/1081899611/34.
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Trexler, Christina M. "Biology, ecology and control of the invasive channeled apple snail, Pomacea canaliculata." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5062.
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Invasive species are detrimental to native biotas worldwide. Recently, Florida was invaded by a freshwater snail (Pomacea canaliculata) native to Argentina. This snail is a serious pest of rice crops in Asia, but little is known about its interactions within Florida ecosystems. Possible competitive exclusion of the native congener (P. paludosa) is a concern because it is the almost exclusive prey of the federally endangered Everglades snail kite (Rostrhamus sociabilis). My research consisted of three parts. First, to identify possible methods to control P. canaliculata in the egg stage, I experimentally evaluated the effects of photoperiod, substrate availability, and food type and availability on hatching success and hatchling survival. None of these factors significantly affected hatching or survival, suggesting that P. canaliculata could invade many water bodies. Second, I used a randomized block design to assess the separate and combined effects of population density and food availability on growth and spawning of P. canaliculata. Food availability but not density significantly affected growth; snails fed less food grew less, but neither factor affected spawning. Third, I used a replacement series design to assess competition between P. canaliculata and P. paludosa under food limitation. For both species, snails fed less grew significantly less, and snails exposed to greater congener densities spawned less than when exposed to conspecifics only. While my results predict that P. paludosa should exclude P. canaliculata, previous literature and current invasions suggest that the exotic snail may co-exist with its North American congener.<br>ID: 030422795; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 53-63).<br>M.S.<br>Masters<br>Biology<br>Sciences
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Alba, Menendez Annia. "Comparative biology of susceptible and naturally- resistant Pseudosuccinea columella snails to Fasciola hepatica (Trematoda) infection in Cuba : ecological, molecular and phenotypical aspects." Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0055/document.
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Pseudosuccinea columella est un des principaux hôtes intermédiaires de Fasciola hepatica, un trématode cosmopolite infectant l’Homme et les animaux domestiques et sauvages, et transmis par des mollusques d’eau douce. L’existence exclusive à Cuba de populations de P. columella qui sont sensibles et naturellement résistantes (encapsulation hémocytaire du parasite) à l’infection par F. hepatica offre un modèle Mollusque-Trématode très intéressant en termes de biologie évolutive, de santé humaine et de stratégies de contrôle vectorielle. L’étude des aspects écologiques, moléculaires et phénotypiques est essentielle pour comprendre les particularités de ce système. Ainsi, nos résultats ont montré que les mollusques sensibles et résistants partagent des exigences écologiques similaires mais chez les résistants la distribution est limitée aux localités avec des eaux acides et peu dures (pH/dureté totale (DT), 6-6.5/4°-10°d) et une richesse des communautés de mollusques très faible, ceci semblant indiquer coût élevé à la résistance. La comparaison de traits d’histoire de vie en laboratoire a permis de confirmer une haute tolérance aux variations de pH/DT de l’eau chez les mollusques résistants mais a montré également une diminution du potentiel reproductif des souches résistantes par rapport aux sensibles. Sur la base de ces observations, des approches «omiques» comparatives ont été entreprises entre souches sensibles et résistantes. Ce travail de thèse nous a aidé à comprendre les particularités de ce modèle hôte-parasite, mais présente également une avancée en termes d’utilisation de la résistance de P. columella à des fins de contrôle de la transmission parasitaire<br>Pseudosuccinea columella is one of the main intermediate hosts of Fasciola hepatica, a cosmopolitan snail-borne trematode that affects humans, livestock and wildlife. The occurrence in Cuba of susceptible and naturally-resistant populations of this species to F. hepatica infection (host’s hemocytes encapsulate the parasite upon penetration) offers an interesting Mollusca - Trematoda model with applications on evolutionary biology, health sciences and vector control strategies. Thus, here we explored different ecological, molecular and phenotypical aspects of this system to better understand P. columella resistance. We determined that while susceptible and resistant snails share similar ecological requirements, resistant populations occurred only at low pH (6.5-6.5) and total hardness (TH; 4°-10°d) waters, with low snail species richness, suggesting a high ecological cost of resistance. Comparison of life history traits between susceptible and resistant snails, experimentally-reared at low or common pH/TH conditions, showed that resistant populations display higher tolerance to pH/TH variations and a lower reproductive potential. To gain more insights on the molecular bases of the features associated to resistance in P. columella, we performed comparative “omics” approaches on naïve snails from both phenotypes at whole snail level (RNAseq) and at the albumen gland level (2D-electrophoresis). This thesis presents the latest efforts to broadly characterize this model, which constitute building steps for the comprehension of P. columella resistance and for its application to tackle parasite transmission
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Breitfuss, Mark, and n/a. "The Effects of Physical Habitat Modification for Mosquito Control, Runnelling, on Selected Non-Target Saltmarsh Resources." Griffith University. Australian School of Environmental Studies, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20031126.074304.
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Runnelling is a popular method of physical habitat modification employed on saltmarshes to control pest mosquito populations. The runnelling method involves linking the tidal source to isolated mosquito breeding pools via shallow channels that enable slow water movement of low amplitude tides. Increased tidal flushing inhibits mosquito development. The range of organisms which inhabit saltmarsh are likely to be influenced by altered tidal conditions as they exhibit specific physicochemical requirements for feeding, burrowing or growth. The dynamic nature of saltmarsh may mean that changes to the tidal frequency of a particular region of the saltmarsh promotes extension of marine-like conditions. Because runnels increase the frequency of flooding tidal events in specific regions of the saltmarsh this study predicted that resulting changes would be evident in the physical conditions of saltmarsh substrate, in the transport of buoyant vegetative propagules, in the population characteristics of surface grazing snails and in the density and aperture of crab burrows after flooding and non-flooding tidal events. The physical impacts of runnelling were determined at three marshes which appeared similar in terms of topography, substrate and tidal conditions. Soil water content and consolidation were measured using two sampling protocols: a) comparisons between modified and unmodified shores; and, b) comparisons with increasing lateral distance across the shore from the runnel edge. At one marsh, moisture levels were significantly higher at runnelled than at unrunnelled sites when tides filled the runnels, but this pattern was not found at the other marshes. Soil consolidation was greater at higher shore heights, but was not different between runnelled and unrunnelled shores. Measurements at different lateral distances from runnels demonstrated higher moisture levels and lower consolidation up to 5 m from the edge but not further away. Groups of marked Avicennia marina propagules were released at the three runnelled saltmarshes during flooding and non-flooding tidal events. Groups of propagules released within 10 m of a runnel were always transported significantly further from the starting position and further up the saltmarsh shore after both flooding and non-flooding tides than any other groups. In addition, the pattern of stranding on saltmarsh for significantly different groups was closely associated with the path of runnel construction so that propagules were located either in the runnel or in depressions linked to the runnel that had been isolated mosquito-breeding pools prior to runnelling. It is likely that altered physical soil conditions significantly affected the distribution and size structures of Salinator solida and Ophicardelus spp. snails recorded at the three saltmarshes. The interaction of tidal period and the presence of a runnel contributed to patterns with significant differences between runnelled and unrunnelled regions of the marsh. Generally, the runnel population of snails exhibited flood-like features even during non-flood periods. The distribution and size classes of snails did not differ with lateral distance from runnels. The burrow characteristics of the crab Helograpsus haswellianus were compared to increase the accuracy of estimating abundance from burrow counts. Including only those burrows which were obviously maintained by resident crabs significantly increased the confidence limits of estimating crab abundance using only burrow density counts. This method was applied to runnelled and unrunnelled sites to assess any changes in the density of burrows associated with the presence of runnels. Again, it is likely that physical soil conditions resulting from increased tidal frequency at the runnel did influence crab burrowing with fewer small burrows being found at the runnelled site, low on the shore. In addition, mid- and large-sized burrows tended to dominate close to the runnel edge. Site-specific soil characteristics may help to explain the lack of continuity in patterns associated with runnel effects on non-target saltmarsh resources. While the runnel may increase the soil water content of clayey substrates at some sites it could also result in de-watering of porous sandy soils at other shores. This was evident in the structure of the snail population and distribution of crab burrows which appeared to reflect altered soil physical characteristics associated with the runnel. Runnelling does affect non-target organisms in saltmarsh. However, the scale of impact was usually locally restricted (< 10 m from the runnel edge). The fact that patterns were not recorded at all sites suggests that the influence of runnels is variable and limited by substrate and some biological conditions. Given the efficiency and popularity of runnelling as a physical control method for reducing pest vector mosquito habitat, this study found no evidence to suggest that its use should be discontinued on any ecological basis measured.
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Viana, Tiago Abreu. "Uso do espaço por Hypselartemon contusulus (Férussac, 1827) (Gastropoda, Streptaxidae) da Trilha da Parnaioca, Ilha Grande, Rio de Janeiro, Brasil." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3525.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>O comportamento espacial dos indivíduos é um componente chave para se entender a
dinâmica de população dos organismos e esclarecer o potencial de migração e dispersão das
espécies. Vários fatores afetam a atividade de locomoção de moluscos terrestres, como temperatura,
luz, umidade, época do ano, tamanho da concha, sexo, estratégia reprodutiva, idade, densidade de coespecíficos
e disponibilidade de alimento. Um dos métodos usados para estudar deslocamento de
gastrópodes terrestres é o de marcação-recaptura. Gastrópodes terrestres se prestam a este tipo de
estudo por causa de (1) seu reduzido tamanho, (2) fácil manejo, (3) fácil captura e (4) pequenas
distâncias de deslocamento e, consequentemente, reduzidas áreas de vida. Estes organismos servem
como modelo para o estudo de ecologia espacial e dispersão. Estudos de população, investigando o
uso do espaço, a distribuição espacial, a densidade populacional e a área de vida são escassos para
moluscos terrestres e ainda mais raros em áreas naturais tropicais. Nosso objeto de estudo é
Hypselartemon contusulus (Férussac, 1827), um molusco terrestre carnívoro, da família Streptaxidae,
muito abundante na serrapilheira, em trechos planos de mata secundária na Trilha da Parnaioca, Ilha
Grande, Rio de Janeiro. A espécie é endêmica para o estado do Rio de Janeiro. Seu tamanho é de até
7,2 mm de altura, apresentando 6 a 7 voltas. Neste trabalho estudamos as variáveis temperatura
ambiente, temperatura do solo, umidade do ar, luminosidade, profundidade do folhiço, tamanho do
animal, densidade de co-específicos e densidade de presas, relacionando estes dados ecológicos ao
deslocamento observado em Hypselartemon contusulus. Uma das hipóteses de trabalho é que estas
variáveis afetam seu deslocamento. O trabalho foi realizado na Ilha Grande, situada ao sul do Estado
do Rio de Janeiro, no município de Angra dos Reis. Os animais foram capturados e marcados com
um código individual pintado na concha com corretor ortográfico líquido e caneta nanquim. As
distâncias de deslocamento, em cm, foram registradas medindo-se as distâncias entre marcadores
subsequentes. Os resultados encontrados indicam que o método utilizado é eficaz para marcar
individualmente Hypselartemon contusulus em estudos de médio prazo (até nove meses). Sugerimos
o uso deste método de marcação para estudos com gastrópodes terrestres ameaçados de extinção,
como algumas espécies das famílias Bulimulidae, Megalobulimidae, Streptaxidae e
Strophocheilidae. Hypselartemon contusulus não mantém uma distância mínima de seus vizinhos, é
ativo ao longo de todo o ano e ao longo do dia, demonstrando atividade de locomoção e predação.
Não foram encontrados animais abrigados sob pedra ou madeira morta. Não foram observados locais
de atividade em oposição a lugares de repouso/abrigo. Beckianum beckianum (Pfeiffer, 1846) foi a
presa preferencial. A densidade populacional variou de 0,57 a 1,2 indivíduos/m2 entre as campanhas
de coleta. A espécie desloca-se, em média, 26,57 17,07 cm/24h, na Trilha da Parnaioca, Ilha
Grande. A área de vida de H. contusulus é pequena, sendo de, no máximo, 0,48 m2 em três dias e
3,64 m2 em 79 dias. O deslocamento da espécie variou ao longo do ano, mas esta variação não é
afetada pelas variáveis ecológicas estudadas. Este é, portanto, um comportamento plástico em H.
contusulus e, provavelmente, controlado por fatores endógenos.<br>Spatial behavior of individuals is a key component to understanding and clarify migration and
dispersion potential of species. Many factors affect locomotory activity of land mollusks, like
temperature, light, humidity, period of the year, shell size, sex, reproductive strategy, age, co-specific
density and food quantity. The mark-recapture method is used to study displacement of land snails.
Land snails lend themselves to this kind of study because of their small size, easy handling, easy
capture and small displacement distances and, consequently, small home ranges. These organisms
serve as model to study spatial ecology and dispersion. Studies on population, concerning spatial
behavior and distribution, population density and home range are rare for land snails and even rariest
in natural tropical areas. Our study object is Hypselartemon contusulus (Férussac, 1827), a
carnivorous land snail, family Streptaxidae, very common in leaf litter, in plane parts of secondary
forest in the Trail of the Parnaioca, Ilha Grande, Rio de Janeiro. The species is endemic to Rio de
Janeiro state. His size is 7.2 mm height, in maximum, showing six to seven whorls. In this work, we
studied the environment variables temperature, soil temperature, air humidity, luminosity, leaf litter
depth, shell size, co-specific density and prey density, connecting these ecologic data to the
displacement observed to H. contusulus. The research hypothesis is that these variables affect its
displacement. The work was carried out in Ilha Grande, south of the state of Rio de Janeiro, in the
Angra dos Reis municipality. The animals were captured and marked with an individual code painted
in the shell with orthographic liquid corrector and nankeen ink. The displacement distances, in cm,
were recorded measuring the distances between subsequent markers. The results indicate that the
used method is effective to mark individually H. contusulus in intermediate-term studies (until nine
months). We suggest the use of this mark method to studies about land threatened land snailst, like
some species of the families Bulimulidae, Megalobulimidae, Streptaxidae and Strophocheilidae.
Hypselartemon contusulus does not maintain a minimum distance from its neighbours. The species is
active during all the day and all year, showing locomotory activity and predation. Animals were not
found sheltered under rock or dead wood. Sites of activity in opposition of sites of resting were not
observed. Beckianum beckianum (Pfeiffer, 1846) was the preferential prey. Population density varied
from 0.57 to 1.2 individuals/m2 between sampling episodes. The species move, in media, 26.57
17.07 cm/24h, in the Trail of the Parnaioca, Ilha Grande. Home range of H. contusulus is small and
does not exceed 0.48 m2, in three days and 3.64 m2 in 79 days. Displacement varied during the year,
but this variation is not affected by the ecological variables. This is a plastic behavior in H.
contusulus and, probably, controlled by endogenous factors.
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Ruehl, Clifton B. "The Interactive Effects of Predators, Resources, and Disturbance on Freshwater Snail Populations from the Everglades." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/266.
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The origins of population dynamics depend on interplay between abiotic and biotic factors; the relative importance of each changing across space and time. Predation is a central feature of ecological communities that removes individuals (consumption) and alters prey traits (non-consumptive). Resource quality mitigates non-consumptive predator effects by stimulating growth and reproduction. Disturbance resets predator-prey interactions by removing both. I integrate experiments, time-series analysis, and performance trials to examine the relative importance of these on the population dynamics of a snail species by studying a variety of their traits. A review of ninety-three published articles revealed that snail abundance was much less in the Everglades and similar ecosystems compared to all other freshwater ecosystems considered. Separating consumptive from non-consumptive (cues) predator effects at different phosphorous levels with an experiment determined that phosphorous stimulated, but predator cues inhibited snail growth (34% vs. 23%), activity (38% vs. 53%), and reproductive effort (99% vs. 90%) compared to controls. Cues induced taller shells and smaller openings and moved to refugia where they reduced periphyton by 8%. Consumptive predator effects were minor in comparison. In a reciprocal transplant cage experiment along a predator cue and phosphorous gradient created by a canal, snails grew 10% faster and produced 37% more eggs far from the canal (fewer cues) when fed phosphorous-enriched periphyton from near the canal. Time-series analysis at four sites and predator performance trials reveal that phosphorous-enriched regions support larger snail populations, seasonal drying removes snails at all sites, crayfish negatively affect populations in enriched regions, and molluscivorous fish consume snails in the wet season. Combining these studies reveals interplay between resources, predators, and seasonality that limit snail populations in the Everglades and lead to their low abundance compared to other freshwater ecosystems. Resource quality is emerging as the critical factor because improving resources profoundly improved growth and reproduction; seasonal drying and predation become important at times and places. This work contributes to the general understanding in ecology of the relative importance of different factors that structure populations and provides evidence that bolsters monitoring efforts to assess the Comprehensive Everglades Restoration Plan that show phosphorous enrichment is a major driver of ecosystem change.
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Montano-Rendon, Mauricio. "Phylogeography of littorinid snails." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/13328/.
Full textAbstract:
Interactions between evolutionary forces such as natural selection, genetic drift and gene flow are complex. Natural selection can lead to parallel formation of phenotypes under similar environmental conditions. Phylogenetic relationships can be inferred from the accumulation of genetic variation caused by genetic drift, regardless of phenotypes. Gene flow between populations can sometimes facilitate the formation of species by natural selection. In this thesis, two groups of marine snails in the diverse subfamily Littorininae were studied. The three rocky-shore species Littorina saxatilis, Littorina arcana and Littorina compressa form one such group, whereas the two sister-species Littoraria cingulata and Littoraria filosa form the other group. Previous studies of the L. saxatilis complex have shown high levels of phenotypic and genetic diversity both at local and broader scales. Previous studies of L. cingulata and L. filosa have found some of the typical signatures of reinforcement. Chapters II and III focused on analysing morphological and genetic variation, respectively, within and among species in the Littorina saxatilis complex from the British Isles. Geometric morphometrics analyses revealed a diversity of shell shape among species, but especially so within L. saxatilis. Shell shape was better explained by environment rather than by geography. Molecular data obtained by high-throughput targeted capture showed the opposite pattern, i.e. genetic variation showed a strong phylogeographic pattern. Chapter IV focused on testing whether reinforcement had contributed towards speciation between Littoraria cingulata and Littoraria filosa. Approximate Bayesian computation analysis supported absence of gene flow between the species in sympatry, suggesting that reinforcement did not contribute towards speciation. However, the results need to be validated and more complex models tested. This thesis highlights the relevance of marine snails in the subfamily Littorininae as model species for addressing a wide range of evolutionary questions. It also provides a wealth of data for many potential follow-up studies.
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Clark, Stephanie A. "Systematics, spatial analysis and conservation genetics of Meridolum corneovirens (Pfeiffer, 1851) and related forms (Gastropoda: Camaenidae) from the Sydney region of Australia /." View thesis, 2005. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20051019.154748/index.html.
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Pinchuck, Shirley Clare. "The ultrastructure and histology of the defensive epidermal glands of some marine pulmonates." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1005481.
Full textAbstract:
Histology and electron microscopy were used to describe and compare the structure of the dorso-lateral pedal defensive glands of three species of marine Basommatophora, Siphonaria capensis, S. serrata and S. gigas. All three species possessed multi-cellular glands that were larger and most abundant in S. capensis. In S. capensis and S. serrata, defensive glands were composed of two types (type I and II) of large secretory cells filled with product and some irregularly shaped support cells that surrounded a central lumen. The product of both cell types was produced by organelles confined to the bases of the cells. The entire gland was surrounded by a well developed layer of smooth muscle and collagen. Type I cells stained positively for neutral and sulphated mucins, and at the transmission electron microscope level the product had a reticulated appearance. By contrast type II gland cells stained very positively for acidic mucins and the secretory product was formed as large granular vesicles. The product from both types of cell, which appeared to be secreted by holocrine secretion, mixed in the lumen of the duct. Individuals of Siphonaria gigas had two types of lateral pedal glands, a large multi-cellular type and a tubular unicellular gland. The multi-cellular glands, which were surrounded by poorly developed muscle, contained one type of gland cell that stained for neutral and sulphated mucins only, as well as some support cells. The tubular glands contained a heterogeneous product that stained very positively for neutral and sulphated mucins. In addition two species of shell-less marine Systellommatophorans, Onchidella capensis and O. hildae, were examined. Onchidellids also posses large marginal, multi-cellular, epidermal glands that produce a repugnatorial secretion. Like the multi-cellular epidermal glands of siphonariids, those of onchidellids are surrounded by layers of smooth muscle. The muscular capsule was particularly well developed in both species of onchidellid, but more so in O. hildae. In addition, this study has shown that unlike siphonariids, muscle fibres run between the gland cells of O. capensis and O. hildae. Unlike siphonariids, onchidellids have a layer of epithelial cells lining the lumen of the gland. The well developed muscle layer and the strands of muscle running between the different gland cells indicates that the glands can be constricted to forcibly propel their secretions along the length of the duct and away from the body of the animal. Based on their product, glands of O. capensis were comprised of five different types of secretory cell and O. hildae only four. Histological and histochemical staining of the glands of showed that the secretory product is largely made up of acidic mucopolysaccharides and neutral and sulphated mucins. A single species from the order Eupulmonata, Trimusculus costatus, was examined and the glands were very different to the species from the siphonariids and onchidellids. Trimusculus costatus does not have large multi-cellular glands encapsulated in a well developed muscle layer, but based on their cell contents, three different types of large unicellular gland cell can be recognised. The glands of T. costatus gave positive results for acid, neutral and sulphated mucins, but negative results for carboxylated mucin. It is possible that the mucous secreted by T. costatus is also an anti-bacterial agent and whilst not totally eliminating bacteria may prevent the accumulation of epibionts on these sedentary limpets. The acidic or sulphated nature of the secretions may help in this role. The defensive mucous secretions of Siphonaria and Onchidella contain polypropionate derivatives, whilst the active ingredients of Trimusculus mucus have been identified as labdane diterpenes, similar to those produced by opisthobranchs. The structure of the glands thought to produce these repungnatorial secretions is very different, with the glands of T. costatus resembling those of the opisthobranchs.
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Rupp, Jens C. "Mate choice and parasitism in freshwater snails." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339354.
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Shigemiya, Yusuke. "Evolution of colour polymorphism in neritid snails." Kyoto University, 2004. http://hdl.handle.net/2433/147702.
Full textAbstract:
Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(人間・環境学)<br>甲第10943号<br>人博第230号<br>15||185(吉田南総合図書館)<br>新制||人||58(附属図書館)<br>UT51-2004-G790<br>京都大学大学院人間・環境学研究科環境相関研究専攻<br>(主査)教授 加藤 真, 教授 松井 正文, 助教授 宮下 英明<br>学位規則第4条第1項該当
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Fearon, Janine Lee. "The genetic diversity and conservation biology of the rare terrestrial snail genus Prestonella." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1003760.
Full textAbstract:
Prestonella bowkeri and Prestonella nuptialis are montane specialists endemic to the southern Great Escarpment of South Africa. Phylogeographic analyses of these species based on mitochondrial markers CO1 and 16S reveal extremely high levels of divergence between populations indicating a lack of gene flow between populations. This is not surprising, because P. nuptialis and P. bowkeri have limited dispersal capacity, low vagility, a highly fragmented distribution and are habitat specialists that are restricted to isolated mesic refugia associated with waterfalls and montane seepages. A relaxed Bayesian clock estimate suggests that populations diverged from one another during the mid-late Miocene (12.5-7 MYA) which coincides with the modern trends of seasonal aridity which began during the Miocene. This result should be viewed with caution because the rates used are at best imprecise estimates of mutation rates in snails. There is no clear dichotomy between the two species and P. bowkeri is paraphyletic with respect to P. nuptialis, as a consequence the taxonomy is unclear. Due to the high levels of sequence divergence between populations they may be considered as evolutionary significant units (ESU’s). An assessment of haplotype diversity (h) and nucleotide diversity (π) reveals that populations in the western part of the Great Escarpment are more genetically depauperate than populations in the east. Correlations between genetic diversity and climatic variables show that genetically depauperate populations are found in areas that have lower annual rainfall, less reliable rainfall and higher potential evaporation, all factors associated with a drier, less mesic environment that increases the chances of a population bottleneck. This indicates that a shift towards a more arid environment may be a driver of genetic erosion. Historical climate change may thus have affected the amount and distribution of genetic diversity across the Great Escarpment since the Miocene. This has serious future implications for the survival of Prestonella. With predicted increase in global temperatures, climate change in South Africa is likely to result in range contraction and an eastward range shift for many species in the drier central and western areas (Erasmus et al. 2002) and regions along the Great Escarpment are likely to become more arid. Prestonella populations found living on inselbergs along the Great Escarpment are already restricted to site specific watercourses and seepages. An increase in the periods between stream flow, and increasing rainfall variability and mean annual potential evaporation are likely to have an adverse affect on species living in these habitats, resulting in further bottlenecks and possibly local extinction. An IUCN assessment of P. nuptialis and P. bowkeri suggests that these two species are probably endangered. The issue surrounding the conservation of Prestonella species is that they are threatened by global climate change, which cannot be simply restricted or prevented, which makes dealing with the threat of climate change difficult. Assisted migration (MA) may be considered as a method to prevent possible future extinctions of Prestonella populations, but will only be considered as a last resort. The thermal tolerance (Arrhenius breaking temperature and flat-line temperature) of individual snails from three Prestonella populations (one forest population and two thicket populations) were assessed using infrared sensors that detected changes in heart rate with increasing temperature. The forest population had a significantly lower Arrhenius breaking temperature (ABT) and flat-line temperature (FLT) than the two thicket population (p<0.05). Our results do not show a correlation between upper thermal limits and maximum habitat temperatures or other climatic variables in Prestonella populations. Although no correlation is found between ABT and maximum habitat temperature, it is likely that the differences seen between these populations are due to local micro-climate adaptation. The climatic variables used in this experiment are coarse estimates from GIS data and do not reflect actual microhabitat conditions. Forest environments are less heat stressed than thicket environments due to the forest canopy which may explain the lower ABT and FLT of the forest population.
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Underwood, G. J. C. "Interactions between freshwater pulmonate snails, macrophytes and epiphytes." Thesis, University of Sussex, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518005.
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Ash, V. B. "Resistance to shell breaking in two intertidal snails." Thesis, University of York, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379538.
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Peters, Howard. "Cone snails : a significant biomedical resource at risk." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/5101/.
Full textAbstract:
Gastropod molluscs of the genus Conus (cone snails) occur throughout the world’s tropical coastal waters where they capture their prey of fish, molluscs or worms using a complex battery of neurotoxins. Although these toxins are of major importance to biomedical science, the conservation status of Conus has been largely ignored. I assessed 632 species of Conus to the standards of IUCN Red List of Threatened Species. This revealed 10.6% of species globally are either threatened or near threatened with extinction, with a further 13.8% data deficient but with indicators that suggest substantial cause for concern. Hotspots of endemism, particularly along the Eastern Atlantic found 42.9% of 98 species there at risk. This includes Cape Verde where 53 of 56 species are endemic and mostly restricted to single islands, and where all three critically endangered and four of eleven globally endangered species occur. The rapid transition of the Cape Verdean economy from services to tourism was found to have placed many Conus species at risk from habitat disturbance and marine pollution. Although the Red List yields valuable data, it is primarily focussed on species nearing extinction. However, many wide-ranging species, exposed to considerable anthropogenic impacts, may, through remoteness and/or depth, remain unnoticed and unrecorded for years, invisible to the Red List as their populations decline. To identify such species I explored the overlap of Conus with biogeographic data of human impacts and future threats from ocean acidification and thermal stress. This revealed a further 67 species occurring in high impact zones deserving further status consideration, and pinpointed regions with high concentrations of endemic taxa under potential threat. This reinforced the benefits of approaching threat assessment from a holistic standpoint in addition to the forensic scrutiny offered by the Red List, allowing proactive conservation management to complement its traditional reactive role.
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Manning, Shawn David. "Susceptibility of Zimbabwean highveld snails to Schistosome infection." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670270.
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Tang, Simon. "Studies on molluscicidal compounds from Phytolacca dodecandra ('Endod') and Millettia thonningii." Thesis, King's College London (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284415.
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Pedder, Sibella Margaretha. "The actions of neuroactive peptides on identified central neurons of Helix aspersa." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302340.
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Cadogan, Anna-Karina. "Characterization of 5-hydroxytryptamine receptors in the snail, Helix aspersa." Thesis, University of St Andrews, 1992. http://hdl.handle.net/10023/14627.
Full textAbstract:
The aim of this investigation was to characterize those 5-HT receptors present in three different tissues of the common garden snail. Helix aspersa, into one or more of the categories already described for vertebrate 5-HT receptors. Specific 5-HT receptor agonists and antagonists which had been developed and used to help characterize, and subsequently classify, the various types of 5-HT receptor in vertebrates, were utilized in this study. The three preparations from Helix included: i) identified neurones in the visceral ganglion ii) the heart and iii) the pharyngeal retractor muscle (PRM). The action of 5-HT on identified neurones in the visceral ganglion was studied using the electrophysiological techniques of both voltage- and current- damp. Under voltage-clamp conditions the response of the identified neurones to iontophoretic application of 5-HT was seen to be an inward current of approximately 3-10 nA. Under current-clamp conditions the response to 5-HT was an excitatory depolarization leading to the firing of action potentials of approximately 3-15 mV. Both responses showed rapid desensitization to repetitive applications of 5-HT and were blocked by tubocurarine. No specific 5-HT receptor antagonist to this 5-HT response in Helix neurones was found. The action of 5-HT was mimicked by 5-CT and a- Me-5-HT both of which showed similar-sized responses to 5-HT, whereas sumatriptan gave smaller responses than those of 5-HT. 5-HT had a positive inotropic effect on the heart. The excitatory action of 5-HT on the heart was studied using an organ bath methodology with application of the 5-HT receptor agonists and antagonists at suitable concentrations. No specific 5-HT receptor antagonist was found for the cardioexcitatory effect of 5-HT. The full rank order of potency for the 5-HT receptor agonists tested was 5-HT > methylergometrine = ergotamine = 5-CT > -Me-5-HT = sumatriptan > methysergide = 2-Me-5-HT = tryptamine 8-OH-DPAT. 5-HT caused relaxation in the PRM and was found to inhibit, in a dose- dependent manner, acetylcholine (ACh)-induced contraction in the muscle. This inhibition of ACh-induced contraction by 5-HT in the PRM was studied using an organ bath methodology with application of 5-HT receptor agonists and antagonists at suitable concentrations. No specific 5-HT receptor antagonist for the inhibition of ACh-induced contraction was found. The rank order of 5-HT receptor agonist potency was 5-HT > 5-CT > sumatriptan = ergotannine = methysergide >> -Me-5-HT = 2-Me-5-HT. The effect of 5-HT on cyclic adenosine 3',5'-monophosphate (cAMP) levels within Helix heart and pharyngeal retractor muscle (PRM) tissue were monitored in this investigation. 5-HT caused a dose-dependent increase in cAMP both in Helix heart and PRM tissue. The 5-HT receptors within Helix are not readily characterized into any of the categories of 5-HT receptor that have been already classified in vertebrates: Helix 5-HT receptors appear to be unique in the fact that they are unclassifiable in terms of the vertebrate 5-HT receptor classification. The evidence presented in this investigation is discussed in terms of the molecular biology of receptors: this includes the hypothesis that the 5-HT receptors particularly in Helix heart and PRM tissue could be related to a family of G-protein-coupled receptors whereas the neuronal 5-HT receptors in Helix are more likely to be integral to an ion channel.
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Lacerda, Luiz Eduardo Macedo de. "Ancylidae (Mollusca, Heterobranchia, Pulmonata, Basommatophora) do Estado do Rio de Janeiro, Brasil: morfologia, sistemática e distribuição geográfica." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2380.
Full textAbstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Os moluscos pateliformes de água doce da região Neotropical são comumente
atribuídos a família Ancylidae sensu latum, abrangendo sete gêneros com pelo menos
13 espécies válidas e sete com identificação duvidosa. Os ancilídeos possuem pequenas
dimensões, alcançam no máximo 15 mm de comprimento. Sua concha é frágil,
composta por duas regiões, a protoconcha e a teleoconcha, as quais apresentam
caracteres relevantes para a sistemática. Na parte mole as impressões musculares, a
pigmentação do manto, o sistema reprodutor e a rádula são importantes para o estudo da
família. Apesar de existirem vários registros de ocorrência para ancílideos no Estado do
Rio de Janeiro (ERJ), existem poucos dados morfológicos. O principal objetivo deste
estudo foi fornecer e ampliar as informações sobre a morfologia e distribuição
geográfica das espécies de Ancylidae encontradas no ERJ. Os materiais utilizados foram
procedentes de coletas próprias, material depositado em Coleções Científicas e dados de
revisão bibliográfica. O estudo da morfologia comparada das conchas foi realizado com
o auxílio de imagens de microscópio óptico e de varredura. Para a comparação das
partes moles, os espécimes foram corados e dissecados sob lupa. Através da
conquiliometria analisamos as diferenças inter e intrapopulacionais. Com este trabalho,
a riqueza conhecida para Ancylidae no ERJ, aumentou de cinco para sete espécies:
Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828),G. ticaga (Marcus &
Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837) e
Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata e U. concentricus
constituem novos registros para o ERJ, e G. radiata para a Região Sudeste. As três
espécies com o maior número de registros de ocorrência no ERJ foram: G. ticaga
(66%), Ferrissia sp. (37%) e Gundlachia sp. (18%). A ampla distribuição de G. ticaga
pode ser devido à capacidade de suportar ambientes impactados. Em relação à
morfologia, Burnupia sp. difere de Burnupia ingae Lanzer, 1991, única espécie deste
gênero descrita para o Brasil, por apresentar diferenças na microescultura da concha e
também na forma das impressões musculares. Ferrissia sp. difere de F. gentilis Lanzer,
1991, devido a diferenças na microescultura apical e número de cúspides no dente
central da rádula. Gundlachia sp. é diferente de G. ticaga e G. radiata, por apresentar a
abertura da concha mais arredondada, ápice mais recurvado, ultrapassando a borda da
concha, pontuações irregulares em toda a protoconcha e forma dos músculos adutores
anterior direito e posterior mais elíptica. A morfologia interna também mostra
diferenças entre Gundlachia sp. e G. ticaga, como o apêndice terminal do útero e o
número de folículos do ovoteste. Através das análises conquiliométricas, constatamos
para os gêneros Burnupia, Ferrrissia e Gundlachia, que os índices morfométricos se
mostraram melhores que as medidas lineares para a discriminação das espécies,
provavelmente porque esses índices diminuem o efeito da amplitude de tamanho das
conchas, que são fortemente influenciadas pelas variações ecofenotípicas. Contudo, os
caracteres diagnósticos das conchas e das partes moles (impressões musculares) são
indispensáveis para a identificação dos gêneros e espécies de Ancylidae.
Palavras-chave: Mollusca. Moluscos de água doce. Morfologia. Distribuição geográfica.
Estado do Rio de Janeiro.uscos.<br>The pateliform freshwater molluscs of the Neotropical region are commonly
attributed to Ancylidae sensu latum, comprising seven genera with at least 13 valid
species and seven with dubious identification. Ancylids are small, reaching up to 15 mm
length. The shell is fragile, composed of two regions: protoconch and teleoconch, which
microsculpture, which is relevant to systematic. In the soft part mantle scars,
pigmentation of mantle, radula and reproductive system are important for the study of
the family. There are several records of occurrence of ancylids in the State of Rio de
Janeiro (SRJ) but few morphological data. The main objective of this study was to
provide and expand morphological and geographical information about Ancylidae
species found in the SRJ. The materials were come from own collections, material
deposited in scientific collections and data for review. A comparative study of shell
morphology was carried out by light and scanning microscope images. To compare the
soft parts, specimens were stained and dissected under a research stereomicroscope.
Interpopulation and intrapopulation variation were studied by shell morphometric
analysis. The richness of Ancylidae in SRJ were increased from five to seven species:
Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828), Gundlachia ticaga
(Marcus & Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837)
e Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata and U. concentricus
are new records for SRJ, and G. radiata to Southeast Brazil. The most frequent three
species in SRJ were: G. ticaga (66%), Ferrissia sp. (37%) and Gundlachia sp. (18%).
The wide distribution of G. ticaga may be due to the ability to survive in impacted
environments. With respect to morphology, the single Burnupia species described from
Brazil, Burnupia ingae Lanzer, 1991, differs from Burnupia sp. in shell microsculpture
and also in the shape of muscle scars. Ferrissia sp. differs from F. gentilis Lanzer, 1991,
due to differences in apical microsculpture and number of cusps on radula central tooth.
Gundlachia sp. is different from G. ticaga and G. radiata, by presenting the shell
opening rounder, more curved apex surpassing the edge of the shell, irregular
punctuations across whole protoconch and the more elliptic right anterior and posterior
adductor muscle scars. The morphology also shows differences between Gundlachia sp.
and G. ticaga, as the terminal appendix of the uterus and the number of follicles of
ovotestis. Shell morphometric analysis found that the indices provided better
discrimination of species than the linear measurements to Burnupia, Ferrrissia and
Gundlachia, probably because these indices decrease the effect of the shells size range
that are strongly influenced by ecophenotipics variations. However, the diagnostic
characters of the shells (microesculpture apical) and soft tissue (muscle scars and mantle
pigmentation) are essential to identify genera and species of Ancylidae.
Keywords: Mollusca. Freshwater snails. Morphology. Geographic distribution. Rio de
Janeiro State.
LISTAe pateliform.
34
Soomro, Noor Mohammad. "Pathology of schistosome infection in mice and vector snails." Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321436.
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Hoso, Masaki. "Handedness coevolution : predator-prey interaction drives speciation in snails." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136933.
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Vazquez, Perera Antonio A. "Interaction hôte – parasite en contexte insulaire : relations entre Fasciola hepatica (Trematoda) et les mollusques Galba cubensis et Pseudosuccinea columella (Gastropoda) sur l’île de Cuba." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS084/document.
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Les interactions hôte – parasites sont des systèmes qui affectent probablement la totalité des êtres vivants et constituent un facteur clé dans la compréhension de la dynamique des maladies infectieuses. On a abordé cette problématique en utilisant le système Fasciola hepatica/Lymnaeidae dans sur l'île de Cuba. Cette thèse utilise une approche basée sur différentes disciplines de la biologie comme l’écologie des populations (distribution et abondances de mollusques hôtes intermédiaires), l'écologie parasitaire (données de prévalences naturelles de parasites chez les hôtes), la génétique des populations en utilisant des marqueurs microsatellites (tant pour le parasite que pour les mollusques hôtes), et des études de susceptibilité et compatibilité douve/limnée.En ce qui concerne la diversité génétique du parasite, une très haute diversité et une forte probabilité d’allofécondation ont été observées. En revanche, on n’a pas trouvé de différentiation significatives entre souches. Les taux d’infection chez le bétail sont très élevés.Pour ce qui est de la biologie des populations des limnées hôtes, on a cartographié la distribution des deux espèces présentes à Cuba : Galba cubensis qui est très répandue et Pseudosuccinea columella qui n'est présente que dans la partie centre-occidentale. Nous avons mis en évidence des différences concernant les types d’habitats préférés pour chaque espèce : G. cubensis est plus plastique écologiquement et se retrouve beaucoup plus dans les sites anthropisés.L'étude des compatibilités douve/mollusque a révélé l’existence de populations avec une résistance naturelle à l’infection par F. hepatica chez la limnée P. columella. Ces populations sont génétiquement différenciées des populations sensibles. La plupart des populations sensibles sont monomorphes avec le même haplotype très répandu. Par contre, on a observé une diversité génétique plus importante chez G. cubensis qui suggère un temps évolutif plus ancien à Cuba. L’échantillonnage fait dans une aire de où la fasciolose sévit fortement chez le bétail a révélé un très faible taux d’infection naturel chez les limnées, mais avec de fortes variations d'intensités. Différentes combinaisons douve/limnée sympatriques et allopatriques testées expérimentalement ont montré une compatibilité supérieure de G. cubensis qui suggère une meilleure adaptation aux souches de F. hepatica cubaines.Les résultats obtenus montrent que la compréhension de la dynamique des maladies infectieuses ainsi que leur contrôle doivent s’appuyer sur des connaissances très solides de la biologie, écologie, génétique et évolution des systèmes hôtes – parasites<br>Host – parasite interactions are biological systems that probably affect every living being. It also constitute a key factor in the understanding of infectious diseases. This subject has been studied using the Fasciola hepatica/Lymnaeidae system in the insular environment of Cuba. This thesis makes a biological multidisciplinary approach through population ecology (distribution and abundance of intermediary hosts snails), infection rates estimations of parasites in their hosts, population genetics using microsatellites markers (for both parasite and snails hosts), and studies of susceptibility and compatibility fluke/snail.The genetic diversity of the parasite is characterized by high values of diversity as well as probability of cross fertilization. However, we failed to detect significant differences between the strains but a highly infection rate is shared in cattle.Regarding the lymnaeid snails, the distribution of the two occurring species is mapped showing that Galba cubensis is widely distributed while Pseudosuccinea columella only exists in central-western Cuba. Both snail species differ in preferred habitat types and G. cubensis displays a higher ecological plasticity commonly observed in heavily human-transformed sites.Differences in host-parasite compatibilities have been revealed. It has been noted the existence of some populations of P. columella with a natural resistance to F. hepatica infection which display a marked differentiation of their population genetic structure compared to susceptible populations. Most susceptible populations are monomorphic with a very common haplotype in Cuba. Conversely, we observed a higher diversity in G. cubensis indicating a larger evolutionary time in Cuba. The sampling conducted in a fasciolosis endemic area revealed very low prevalences in the snail populations. However, strong variation in parasite mean intensity within individuals supports the high infection rates observed in cattle. Different sympatric and allopatric fluke/snail combinations were experimentally tested in which G. cubensis proved to be more compatible and suggest a better adaptation to the circulating F. hepatica in Cuba.Our results show that the understanding of infectious diseases’ dynamics and their effective control must strictly rely in a full knowledge of the biology, ecology, genetics and evolution of host – parasite systems
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Gerlach, Justin. "The ecology of the carnivorous snail Euglandina rosea." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308609.
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Tomba, Abbie Marie Feminella Jack W. "Effects of trematode parasites on habitat use and disturbance response of freshwater snails in the genus Elimia." Auburn, Ala., 2006. http://repo.lib.auburn.edu/Send%2012-15-07/TOMBA_ABBIE_52.pdf.
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Exton, Samantha Jane. "Natural selection in fossil and recent molluscs." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366482.
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Campbell, Gillian. "Molecular evolution and population genetics of Biomphalaria (Mollusca: Gastropoda)." Thesis, University of Aberdeen, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275031.
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Hanley, Michael Edward. "The influence of molluscan herbivory on seedling regeneration in grassland." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296377.
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Ribeiro, Maria JoseÌ Braga Marques. "Molecular mechanisms of appetitive learning in the pond snail Lymnaea stagnalis." Thesis, University of Sussex, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247995.
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Raymond, Katherine Mary. "Studies on the inter-relationships between Schistosoma species and bulinid snails." Thesis, Bangor University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302958.
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White, Jessica C. "Comparative Bioavailability of Dietary and Dissolved Cadmium to Freshwater Aquatic Snails." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4351/.
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Heavy metal bioaccumulation in aquatic organisms may occur through direct or indirect uptake routes. Research indicates that the significance of uptake route varies with contaminant and organism exposed. The relative importance of different metal sources in aquatic systems was investigated by exposing freshwater snails to dietary or dissolved sources of cadmium. Snails were exposed to control, contaminated food only, contaminated water only, and contaminated food and water treatments. During the 15-day exposure, samples were taken to determine Cd concentration in snail soft tissue, snail shell, algal food, and overlying water. Analyses of snail soft tissue and shells indicate that exposure route significantly affects Cd concentrations in the tissues. In both cases, dissolved Cd is the primary contributor to metal body burden.
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Al-Qattan, Nasser M. E. N. A. A. "Interpretation of Oxygen Isotopic Values (d18O) of North American Land Snails." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1404460805.
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Leone, Stacy E. "Predator induced plasticity in barnacle shell morphology /." Abstract Full Text (HTML) Full Text (PDF), 2008. http://eprints.ccsu.edu/archive/00000496/02/1952FT.htm.
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Thesis (M.A.) -- Central Connecticut State University, 2008.<br>Thesis advisor: Jeremiah Jarrett. "... in partial fulfillment of the requirements for the degree of Master of Arts in Biology." Includes bibliographical references (leaves 27-29). Also available via the World Wide Web.
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Wheater, C. P. "Feeding strategies in some predacious Coleoptera." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253705.
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Whitwam, Ross Edward Carleton University Dissertation Biology. "The Covalent modification of phosphofructokinase and pyruvate kinase in the hypometabolic pulmonate Otala Lactea." Ottawa, 1988.
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Kistner, Erica Jean. "Adaptive responses and invasion the role of plasticity and evolution in snail shell morphology /." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/e_kistner_042509.pdf.
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Thesis (M.S. in zoology)--Washington State University, May 2009.<br>Title from PDF title page (viewed on Oct. 09, 2009). "School of Biological Sciences." Includes bibliographical references (p. 77-82).
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Crossley, Michael. "Neural mechanisms of decision making in the pond snail Lymnaea stagnalis." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/48861/.
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The aim of this thesis was to identify key neural mechanisms underlying decision making in a model invertebrate system, the pond snail Lymnaea stagnalis. Specifically, this was examined with respect to two decision making processes associated with Lymnaea's feeding behaviour; first a stimulus present/stimulus absent perceptual decision making task for selecting between appetitive and consummatory behaviours, second a behavioural choice between ingestion and egestion. A behavioural paradigm was designed in order to study stimulus present and stimulus absent decision making in Lymnaea. The switch between appetitive and consummatory behaviours was used as a read out of the decision. During stimulus absent decisions, the animal made a judgement about the absence of a sensory stimulus and entered into a period of quiescence. During stimulus present decisions the animal switched from the appetitive behaviour into the consummatory behaviour. The decision about the presence of a stimulus was reliant on the tactile cues from the potential food. Importantly the task was amenable for in vitro preparations and the identification of the decision neurons. A candidate stimulus present decision neuron, the ventral trigger neuron (vTN), was identified in the buccal ganglia. vTN received appropriate sensory input and was able to initiate fictive feeding cycles. vTN was able to initiate fictive feeding cycles via monosynaptic connections with feeding central pattern generator (CPG) interneurons. Development of an in vitro paradigm of the stimulus present and stimulus absent decision provided strong evidence that vTN was a stimulus present decision neuron. A stimulus absent decision neuron was identified as the inhibitory interneuron and member of the feeding CPG, N3t. An in vitro paradigm was used to test interactions of the stimulus present decision neuron with the stimulus absent decision neuron. Goal directed behaviours were also shown to lower the threshold of activity needed for vTN to initiate fictive consummatory behaviours, lowering the sensory threshold needed for stimulus present decisions to be made. The neural mechanism of behavioural choice between ingestion and egestion in Lymnaea was characterised using in vivo and in vitro preparations. A novel motor neuron was identified whose phase of firing activity was selectively shifted between the two behaviours. The interneuronal control of ingestion was identified and consisted of previously identified command-like neurons, whereas the interneuronal control of egestion consisted of novel interneurons located in the buccal ganglia. The two networks showed evidence of both dedicated and multifunctional interneurons. The studies presented in this thesis demonstrate that even within the same relatively simple neural network several distinct mechanisms are utilised for different types of decision. These were identified at the level of individual neurons and their synaptic connectivity. Uniquely in these studies, distinct stimulus absent and stimulus present decision neurons were identified in the perceptual decision task and it was also shown that performing the decision making task facilitates the stimulus present decision. This provides fundamental new insights into the neural mechanisms of decision making. The studies also provide a model system for comparison between a form of decision making studied extensively in mammals (perceptual decision making in a stimulus absent/stimulus present task) and a form studied primarily in invertebrates (behavioural choice between two incompatible behaviours), bridging the gap between invertebrate and vertebrate decision making studies.