Academic literature on the topic 'Bioclimatic niche'

The study of the evolution of abiotic niches can be informative regarding the speciation drivers in a given group. Yet, two factors that could potentially affect niche evolution have seldom been addressed concomitantly, which are biotic interactions and geographical isolation. In this study, we used as a model group the Antillean plant genera Gesneria and Rhytidophyllum (Gesneriaceae) to evaluate the effect of pollinators and geographical isolation on the bioclimatic niche. These genera possess species characterized by interspecific geographical isolation in different islands and are pollinated by different pollinators. Some species are pollinated by hummingbirds, other by bats, while some are more generalists and are pollinated by pollinators from both functional groups. After describing the bioclimatic niches of plant species, we measured niche overlap for species pairs and we fitted Brownian motion and Ornstein–Uhlenbeck (OU) evolution models with multiple evolutionary regimes to test for an effect of pollination strategy or geographical isolation on bioclimatic niche evolution of these plants. The analysis of niche overlap between plant species, which could not be corrected for phylogenetic relationships, showed that it was significantly influenced by pollination mode and island distribution. By contrast, the best fitting evolutionary model on niche optima and tolerance was always an OU model with a unique selective regime, suggesting that neither pollination strategy nor island isolation had an important effect on bioclimatic niches at a macroevolutionary scale. Instead, we conclude that bioclimatic niches of Antillean Gesneriaceae evolved under phylogenetic conservatism and hypothesize that this macroevolutionary pattern could result from adaptation to temporally variable climates in the Antilles.

The cold-climate hypothesis maintains that viviparity arose as a means to prevent increased egg mortality in nests owing to low temperatures, and this hypothesis represents the primary and most strongly supported explanation for the evolution of viviparity in reptiles. In this regard, certain authors have stated that viviparous species will exhibit speciation via climatic niche conservatism, with similar climatic niches being observed in allopatric sister species. However, this prediction remains to be tested with bioclimatic variables relevant to each viviparous group. In the present study, we examined climatic niche evolution in a group of North American viviparous lizards to determine whether their diversification is linked to phylogenetic niche conservatism (PNC). We evaluated the phylogenetic signal and trait evolution of individual bioclimatic variables and principal component (PC) scores of a PC analysis, along with reconstructions of ancestral climate tolerances. The results suggest that diversification of theSceloporus torquatusgroup species is associated with both niche differentiation and PNC. Furthermore, we did not observe PNC across nearly all bioclimatic variables and in PC2 and PC3. However, in Precipitation Seasonality (Bio15), in Precipitation of Coldest Quarter (Bio19) and in PC1 (weakly associated with variability of temperature), we did observe PNC. Additionally, variation of the scores along the phylogeny and Pagel’s delta (δ) >1 of PC3 suggests a fast, recent evolution to dry conditions in the clade that sustainsS. serrifer.

Abstract In this study an attempt is made to highlight important variables shaping the current bioclimatic niche of a number of mite species associated with the infestation of stored products by employing a species distribution modeling (SDM) approach. Using the ENVIREM dataset of bioclimatic variables, performance of the most robust models was mostly influenced by: 1) indices based on potential evapotranspiration, which characterize ambient energy and are mostly correlated with temperature variables, moisture regimes, and 2) strong fluctuations in temperature reflecting the severity of climate and/or extreme weather events. Although the considered mite species occupy man-made ecosystems, they remain more or less affected by the surrounding bioclimatic environment and therefore could be subjected to contemporary climate change. In this respect investigations are needed to see how this will affect future management targets concerning the safety of food storages.

The tropical rainforest is one of the lushest and most important plant communities in Mexico’s tropical regions, yet its potential distribution has not been studied in current and future climate conditions. The aim of this paper was to propose priority areas for conservation based on ecological niche and species distribution modeling of 22 species with the greatest ecological importance at the climax stage. Geographic records were correlated with bioclimatic temperature and precipitation variables using Maxent and Kuenm software for each species. The best Maxent models were chosen based on statistical significance, complexity and predictive power, and current potential distributions were obtained from these models. Future potential distributions were projected with two climate change scenarios: HADGEM2_ES and GFDL_CM3 models and RCP 8.5 W/m2 by 2075–2099. All potential distributions for each scenario were then assembled for further analysis. We found that 14 tropical rainforest species have the potential for distribution in 97.4% of the landscape currently occupied by climax vegetation (0.6% of the country). Both climate change scenarios showed a 3.5% reduction in their potential distribution and possible displacement to higher elevation regions. Areas are proposed for tropical rainforest conservation where suitable bioclimatic conditions are expected to prevail.

Brunnera sibirica is a Southern-Siberian endemic herb. Being a Pliocene relict, it is included in Red Data Books of many Siberian regions. The aim of our study was to identify the climatic niche and territories suitable for this vulnerable species using the MaxEnt method. The climatic profile of B. sibirica was constructed using the BIOCLIM method with 19 bioclimatic variables. The research has revealed that the climatic conditions in the most of Siberian territory are not suitable for the growth of B. sibirica, which confirms its relic origin in the south of Siberia.

Abstract The aim of this paper was firstly to describe the ecological and geographical differentiation of the four maple species (Acer spp.) in Serbia and Kosovo based on floristic and phytocoenological data, and secondly, to model their distributions in order to predict which areas the species can be expected in. The intention was also to compare the resulting prediction maps with the available field records and see whether there are any differences between the actual and the predicted ranges. The data set included 1979 species records and each record was accompanied by geographic coordinates. The geographi-cal analysis was performed on the chorological data (latitude, longitude, altitude), while the ecological was based on vegetation data relating to the association, alliance, order and class as well as on 19 bioclimatic parameters. The data set was georeferenced using GIS tools. The results demonstrated that the distribution patterns of all the analyzed species are mostly affected by the limiting effects of the variables related to precipitation and temperature of the dry and also the warm period. Their synergic limiting effects are the most important force shaping distribution patterns within a territory. These findings highlight the importance of defining bioclimatic profiles of species using different techniques of distribution modelling.

Abstract Maximum entropy niche modeling was employed as a tool to assess potential habitat suitability for the freshwater snail F. esperi (Férussac, 1823) in Ukraine for both contemporary climatic conditions and conditions projected for 2050. Of the 19 bioclimatic predictor variables used in the modeling, the “mean temperature seosonality” “mean temperature of driest quarter” and “precipitation of warmest quarter” were the three most important in predicting habitat suitability and distribution of this mollusk species.

Each species besides of having the unique morphological pattern also has an unique ecologo-climatic niche and geographical range. The study of ecologico-climatic and geographic divergence can make significant contribution to understanding of the species genesis and its volume. The purpose of this paper was to compare the ecologo-climatic niches of the closely related species Stipa sareptana and S. krylovii in order to reveal their identity. The research allowed specifying the areas of both species. Using GIS methods and based on the points of presence and six independent bioclimatic characters, their potential ranges – areas where the climatic conditions are favorable for growth – were identified and ecologo-climatic niches revealed. It was established that the most important factors determining the distribution of S. krylovii and S. sareptana are the mean annual temperature and seasonality of precipitation. Other factors play a subordinate role. The comparison of ecological niches, generated by MaxEnt, showed their differences at a statistically significant level.

The Important Bird Areas (IBAs) network of BirdLife International aims to identify sites that are essential for the long-term conservation of the world’s avifauna. A number of global change events have the potential to negatively affect, either directly or indirectly, most bird species, biodiversity in general and associated ecological processes in these areas identified as IBAs. To assist conservation decisions, I assessed a suite of ten landscape scale anthropogenic pressures to 115 Important Bird Areas (IBAs) in South Africa, both those currently placing pressures on IBAs and those that constitute likely future vulnerability to transformation. These threats are combined with irreplaceability, a frequently used measure of conservation importance, to identify the suite of IBAs which are high priority sites for conservation interventions: those with high irreplaceability and are highly vulnerable to anthropogenic threats. A total of 22 (19%) of the South African IBAs are highly irreplaceable and are highly vulnerable to at least some of the pressures assessed. Afforestation, current and potential future patterns of alien plant invasions affect the largest number of highly irreplaceable IBAs. Only 9% of the area of highly irreplaceable IBAs is formally protected. A total of 81 IBAs (71%) are less than 5% degraded or transformed. This result, together with seven highly irreplaceable IBAs found outside of formally protected areas with lower human densities than expected by chance provides an ideal opportunity for conservation interventions. However, all the pressures assessed vary geographically, with no discernible systematic pattern that might assist conservation managers to design effective regional interventions. Furthermore, I used the newly emerging technique of ensemble forecasting to assess the impact of climate change on endemic birds in relation to the IBAs network. I used 50 endemic species, eight bioclimatic envelope models, four climate change models and two methods of transformation to presence or absence, which essentially creates 2400 projections for the years 2070-2100. The consensual projection shows that climate change impacts are very likely to be severe. The majority of species (62%) lose climatically suitable space and 99% of grid cells show species turnover. Five species lose at least 85% of climatically suitable space. The current locations of the South African Important Bird Areas network is very likely ineffective to conserve endemic birds under climate change along a “business a usual” emissions scenario. Many IBAs show species loss (41%; 47 IBAs) and species turnover (77%; 95 IBAs). However, an irreplaceability analysis identified mountainous regions in South Africa as irreplaceable refugia for endemic species, and some of these regions are existing IBAs. These IBAs should receive renewed conservation attention, as they have the potential to substantially contribute to a flexible conservation network under realistic scenarios of climate change. Considering all the global change threats assessed in this study, the Amersfoort-Bethal-Carolina District and the Grassland Biosphere Reserve (IBA codes: SA018; SA020) are the key IBAs in South Africa for conservation prioritisation.
Dissertation (MSc)--University of Pretoria, 2008.
Zoology and Entomology
unrestricted

Contexte : Gesneria et Rhytidophyllum (Gesneriaceae) sont deux genres de plantes Antillais aillant subi une forte diversification et qui présentent une forte variabilité de modes de pollinisation associés à des traits floraux particuliers. Les spécialistes des colibris ont des fleurs tubulaires rouges, alors que les spécialistes des chauves-souris et les généralistes présentent des fleurs campanulées de couleur pâle. La capacité d’être pollinisé par des chauves-souris (en excluant les colibris ou en devenant généraliste) a évolué plusieurs fois indépendamment au sein du groupe. Ces caractéristiques font de ces plantes un bon modèle pour étudier les relations entre l’évolution des modes de pollinisation et la diversification spécifique et écologique. Pour ceci, nous avons étudié les bases génétiques des changements de mode de pollinisation et les liens entre ces modes de pollinisations et la diversification des niches bioclimatiques. Méthodes : Nous avons réalisé une étude de QTLs pour caractériser les régions génomiques associées à la transition de syndrome de pollinisation entre une espèce à stratégie de pollinisation mixte (Rhytidophyllum auriculatum) et une espèce spécialiste des colibris (Rhytidophyllum rupincola). Nous avons parallèlement analysé les relations entre les changements de modes de pollinisation (dimension biotique de la niche écologique) et l’évolution des niches bioclimatiques chez ces plantes. Enfin, d’un point de vue théorique, nous avons testé l’effet de la fréquence et de l’amplitude des changements environnementaux sur les patrons d’évolution des niches écologiques. Résultats : L’étude des QTLs a montré que la couleur et le volume de nectar sont basés chacun sur un QTL majeur, alors que la forme de la corolle a une base génétique plus complexe. Par ailleurs ces différents QTLs ne sont pas liés physiquement dans le génome. L’analyse des niches bioclimatiques a montré que ces Gesneriaceae antillaises sont caractérisées par un conservatisme phylogénétique de niche bioclimatique (PNC) et que l’évolution de ces niches est indépendante des stratégies de pollinisation. Les plantes semblent aussi être relativement généralistes du point de vue de leur niche abiotique. Finalement, nous avons testé l’hypothèse selon laquelle l’adaptation à un environnement temporellement hétérogène pourrait expliquer à la fois le caractère généraliste des plantes et leur patron de PNC. Cette hypothèse s’est trouvée partiellement vérifiée. Conclusion : Si l’indépendance génétique des traits floraux a pu faciliter l’émergence des syndromes de pollinisation en réduisant les contraintes génétiques, il semble que la répartition largement chevauchante des colibris et des chauves-souris ne représente pas une opportunité écologique suffisante pour expliquer les évolutions répétées vers la pollinisation par les chauves-souris. En revanche, les perturbations environnementales causant régulièrement des déclins dans les populations de pollinisateurs pourraient expliquer l’avantage des plantes qui ont une stratégie de pollinisation mixte.
Background: Gesneria and Rhytidophyllum (Gesneriaceae) are two genera endemic to the Antilles that underwent an important diversification and that present a great vari- ability in pollination modes with regard to specific floral traits. Hummingbird specialists harbour red tubular flowers while bat specialists and generalists have campanulate (i.e., bell shaped) flowers with pale colours. Bat pollination (excluding or not hummingbirds) evolved multiple times independently in this group. These plants are thus a good model to study the relationship between the evolution of pollination mode and ecological and species diversification. To understand these relationships, we studied the genetic basis of pollination mode transition and the link between pollination mode and bioclimatic niches diversification. Methods: We performed a QTL analysis to detect genomic regions underlying the floral traits involved in the pollination syndrome transition between Rhytidophyllum auriculatum (a generalist species) and Rhytidophyllum rupincola (a hummingbird specialist). Also, we analysed the consequence of pollination mode transitions (which represent the biotic part of ecological niches) on bioclimatic niches evolution in Gesneria and Rhytidophyllum. Then, we tested whether environmental changes can result in patterns of phylogenetic bioclimatic niche conservatism through time. Results: The QTLs analysis showed that corolla colour and nectar volume are both based on one major QTL, while corolla shape is determined by a more complex genetic architecture involving several unlinked QTLs. These Antillean Gesneriaceae were found to have a pattern of phylogenetic (bioclimatic) niche conservatism (PNC) and their niche evolution was found to be independent from pollination strategies. Overall, the plants were found to have relatively widespread bioclimatic niches. Finally, we partially confirmed the hypothesis that adapting to temporally variable environment might cause both species generalization and PNC pattern. Conclusion: Genetic independence of floral traits might have facilitated pollination syn- dromes evolution by reducing genetic constraints. However, the overlapping distribution of hummingbirds and bats do not represent an ecological opportunity that could explain re- peated evolutions toward bat pollination. However, environmental perturbations causing regular pollinator populations collapses could explain the advantage for plants to favour generalist strategies.

The Important Bird Areas (IBAs) network of BirdLife International aims to identify sites that are essential for the long-term conservation of the world’s avifauna. A number of global change events have the potential to negatively affect, either directly or indirectly, most bird species, biodiversity in general and associated ecological processes in these areas identified as IBAs. To assist conservation decisions, I assessed a suite of ten landscape scale anthropogenic pressures to 115 Important Bird Areas (IBAs) in South Africa, both those currently placing pressures on IBAs and those that constitute likely future vulnerability to transformation. These threats are combined with irreplaceability, a frequently used measure of conservation importance, to identify the suite of IBAs which are high priority sites for conservation interventions: those with high irreplaceability and are highly vulnerable to anthropogenic threats. A total of 22 (19%) of the South African IBAs are highly irreplaceable and are highly vulnerable to at least some of the pressures assessed. Afforestation, current and potential future patterns of alien plant invasions affect the largest number of highly irreplaceable IBAs. Only 9% of the area of highly irreplaceable IBAs is formally protected. A total of 81 IBAs (71%) are less than 5% degraded or transformed. This result, together with seven highly irreplaceable IBAs found outside of formally protected areas with lower human densities than expected by chance provides an ideal opportunity for conservation interventions. However, all the pressures assessed vary geographically, with no discernible systematic pattern that might assist conservation managers to design effective regional interventions. Furthermore, I used the newly emerging technique of ensemble forecasting to assess the impact of climate change on endemic birds in relation to the IBAs network. I used 50 endemic species, eight bioclimatic envelope models, four climate change models and two methods of transformation to presence or absence, which essentially creates 2400 projections for the years 2070-2100. The consensual projection shows that climate change impacts are very likely to be severe. The majority of species (62%) lose climatically suitable space and 99% of grid cells show species turnover. Five species lose at least 85% of climatically suitable space. The current locations of the South African Important Bird Areas network is very likely ineffective to conserve endemic birds under climate change along a “business a usual” emissions scenario. Many IBAs show species loss (41%; 47 IBAs) and species turnover (77%; 95 IBAs). However, an irreplaceability analysis identified mountainous regions in South Africa as irreplaceable refugia for endemic species, and some of these regions are existing IBAs. These IBAs should receive renewed conservation attention, as they have the potential to substantially contribute to a flexible conservation network under realistic scenarios of climate change. Considering all the global change threats assessed in this study, the Amersfoort-Bethal-Carolina District and the Grassland Biosphere Reserve (IBA codes: SA018; SA020) are the key IBAs in South Africa for conservation prioritisation.
Dissertation (MSc)--University of Pretoria, 2011.
Zoology and Entomology
unrestricted

Adaptation to climatic conditions is a major ecological and evolutionary driver. Long-term study of European badger population dynamics in Oxfordshire reveals that rainfall and temperature patterns affect food (principally earthworm) availability, energy expended in thermoregulation, and activity patterns, with badgers able to seek refuge in their setts. Cubs prove especially vulnerable to harsh weather conditions, where drought and food shortages exacerbate the severity of pandemic juvenile coccidial parasite infections. Crucially, weather variability, rather than just warming trends, stresses badgers, by destabilising their bioclimatic niche. Summer droughts cause mortality, even driving genetic selection; and while milder winters generally benefit badgers, less time spent in torpor leads to more road casualties. Similar effects also operate over a wide spatial scale in Ireland, impacting regional badger densities and bodyweights. That even an adaptable, generalist musteloid is so variously susceptible to weather conditions highlights how climate change places many species and ecosystems at risk.