With close to 2100 species, the flowering plant genus Carex (Cyperaceae; sedges) is an example of an evolutionary radiation. Despite its potential for use as a model taxon in evolutionary studies, the diversification of sedges remains largely unexplored. This thesis realizes the potential of Carex as an evolutionary model group by using it to ask questions about species richness patterns. More specifically, it seeks to determine the relationship, if any, between rates of trait evolution and species richness. This tests the hypothesis that organisms with increased abilities to evolve new traits, speciate more rapidly. Morphological and ecological (habitat and climatic niche) traits are modelled on a nearly complete regional (North America north of Mexico) phylogeny and rates of trait evolution are compared among non-nested sister groups. However, before trait evolution is modelled, this work evaluates the sensitivity of climatic niche estimates to underlying distribution datasets. It tests the agreement of niche estimates derived from the commonly used online repository GBIF (the Global Biodiversity Information Facility) and county-level distributions via BONAP (the Biota of North America Program). Results showed that in the context of phylogenetic comparative analyses, it is not vital to obtain highly accurate climatic niche estimates. The second study found significant positive correlations between the rates of climatic niche, habitat and reproductive morphological evolution and species richness. This result supports the role of high trait lability in generating species richness and more generally, the idea that high trait disparity through evolutionary time leads to species success.

A major goal of ecology and evolutionary biology is to explain patterns of species richness among clades. Differences in rates of net diversification (speciation minus extinction over time) may often explain these patterns, but the factors that drive variation in diversification rates remain uncertain. Three important candidates are climatic niche position (e.g., whether clades are primarily temperate or tropical), rates of climatic niche change among species within clades, and microhabitat (e.g., aquatic, terrestrial, arboreal). The first two factors have been tested separately in several studies, but the relative importance of all three is largely unknown. Here we explore the correlates of diversification among families of frogs, which collectively represent approximate to 88% of amphibian species. We assemble and analyze data on phylogeny, climate, and microhabitat for thousands of species. We find that the best-fitting phylogenetic multiple regression model includes all three types of variables: microhabitat, rates of climatic niche change, and climatic niche position. This model explains 67% of the variation in diversification rates among frog families, with arboreal microhabitat explaining approximate to 31%, niche rates approximate to 25%, and climatic niche position approximate to 11%. Surprisingly, we show that microhabitat can have a much stronger influence on diversification than climatic niche position or rates of climatic niche change.

A major goal of evolutionary biology and ecology is to understand why species richness varies among clades. Previous studies have suggested that variation in richness among clades might be related to variation in rates of morphological evolution among clades (e.g., body size and shape). Other studies have suggested that richness patterns might be related to variation in rates of climatic-niche evolution. However, few studies, if any, have tested the relative importance of these variables in explaining patterns of richness among clades. Here, we test their relative importance among major clades of Plethodontidae, the most species-rich family of salamanders. Earlier studies have suggested that climatic-niche evolution explains patterns of diversification among plethodontid clades, whereas rates of morphological evolution do not. A subsequent study stated that rates of morphological evolution instead explained patterns of species richness among plethodontid clades (along with "ecological limits" on richness of clades, leading to saturation of clades with species, given limited resources). However, they did not consider climatic-niche evolution. Using phylogenetic multiple regression, we show that rates of climatic-niche evolution explain most variation in richness among plethodontid clades, whereas rates of morphological evolution do not. We find little evidence that ecological limits explain patterns of richness among plethodontid clades. We also test whether rates of morphological and climatic-niche evolution are correlated, and find that they are not. Overall, our results help explain richness patterns in a major amphibian group and provide possibly the first test of the relative importance of climatic niches and morphological evolution in explaining diversity patterns.

Anthropogenic climate change is one of the most important factors influencing population growth and survival. Therefore, to be able to predict the effect of climate change on ecosystem composition and function, it is important to understand its effect on demographic variables, such as productivity. As a measure of productivity, I related the proportion of yearling birds captured during bird ringing in southern Sweden with mean temperature during the breeding season. I then compared the relationship between temperature and productivity for species with different traits regarding number of broods produced per season, thermal niches and migration behaviours. For most species (72%), productivity positively related to temperature during the breeding season. The relationship was strongest for species with the ability to vary the number of broods per year and species with a warmer thermal niche, whereas there was no difference between long-distance migratory and short-distance migratory species. The results suggest that, for some bird species in the study area, climate warming can increase population sizes. However, long-term effects of climate change may be different than the interannual fluctuations of temperature considered in this study, especially when interacting effects of habitat losses are taken into account.

Either tropical niche divergence or tropical niche conservatism could drive the latitudinal diversity gradient. Greater niche divergence in the tropics could accelerate reproductive isolation leading to more rapid species formation. Alternatively, latitudinal asymmetry in niche conservatism, whereby tropical species are more conserved than high latitude species, could promote more dispersal in to than out of the tropics, leading to greater tropical richness. Here I test whether rates of climatic niche evolution vary across the latitudinal gradient for 164 closely related pairs of species. Using the evolutionary ages at which sister species diverge, and the niche divergence between them, I applied Brownian motion models to test whether rates of climatic niche evolution varied with latitude. My results indicate that climatic niche conservatism is strongest in the tropics. This suggests that the latitudinal diversity gradient is driven by the inability of tropical to adapt to temperate climates and colonize non-tropical latitudes.

Either tropical niche divergence or tropical niche conservatism could drive the latitudinal diversity gradient. Greater niche divergence in the tropics could accelerate reproductive isolation leading to more rapid species formation. Alternatively, latitudinal asymmetry in niche conservatism, whereby tropical species are more conserved than high latitude species, could promote more dispersal in to than out of the tropics, leading to greater tropical richness. Here I test whether rates of climatic niche evolution vary across the latitudinal gradient for 164 closely related pairs of species. Using the evolutionary ages at which sister species diverge, and the niche divergence between them, I applied Brownian motion models to test whether rates of climatic niche evolution varied with latitude. My results indicate that climatic niche conservatism is strongest in the tropics. This suggests that the latitudinal diversity gradient is driven by the inability of tropical to adapt to temperate climates and colonize non-tropical latitudes.

La niche climatique des espèces joue un rôle important dans la distribution spatiale de la biodiversité mais la manière dont les niches climatiques évoluent reste encore peu connue. Ce travail vise à révéler la manière dont les niches climatiques évoluent en général, et plus précisément à déterminer comment certaines plantes se sont adaptées aux environnements alpins. En étudiant de nombreux groupes de plantes, de poissons, de mammifères et d'oiseaux, nous avons montré que les niches climatiques évoluent le plus souvent par à-coups et non pas de manière graduelle. Les niches climatiques restent en effet stables pendant des périodes de plusieurs millions d'années puis évoluent de manière extrêmement rapide avant de se stabiliser à nouveau dans une autre gamme de climat. Des simulations ont permis de montrer que les phases de relative stabilité n'étaient pas forcément causées par une sélection stabilisante sur les niches climatiques mais pouvaient également résulter de la présence de barrières géographiques qui empêchent les espèces d'expérimenter de nouveaux climats. L'étude de l'histoire des plantes du genre Androsace a révélé que les changements rapides de niches correspondaient au contraire à l'apparition de nouveaux traits, comme la forme de vie en coussin. Ce travail montre que de nombreux facteurs influencent l'évolution des niches climatiques et souligne la nécessité de tous les étudier ensemble. / Species' climatic niches play an important role in the spatial distribution of biodiversity but the way climatic niches evolve remains poorly known. This works aims at determining the general mode of evolution of climatic niches, and more precisely at revealing how some plants have adapted to alpine environments. The study of many groups of plants, fishes, mammals and birds has shown that climatic niches usually evolve by fits and starts but not gradually. Climatic niches indeed remain stable over million years before evoving extremely quickly and stabilizing again in a new range of climates. Simulations have shown that these phases of relative stability need not be caused by stabilizing selection but can also be caused by geographic barriers that impede species from experiencing new climates. The study of the history of plants of the genus Androsace has revealed that rapid niche shifts on the contrary resulted from the appearing of novel traits, like the cushion life form. This work shows that numerous factors contribute to the evolution of climatic niches and emphasizes the necessity to study them together.

The geographic variation of taxonomic richness may be directly determined by climate through contemporaneous/ecological processes, versus other (e.g., historical/evolutionary processes) that happen to be collinear with contemporaneous climate. In Chapter 1 I evaluated hypotheses from both groups of explanations in North America. If contemporaneous climate controls patterns of richness, then richness should vary with climate through time in the same way that richness varies with current climate through space. Over the last ca. 11,000 yr, richness-temperature relationships remained reasonably constant. Between 12,000 and 14,000 yr BP, when climate fluctuated rapidly, richness gradients as a function of temperature were significantly shallower. If historical climate over the last 21,000 years determines patterns of richness, then historical climate should be a better predictor of richness than contemporaneous climate. I rejected historical-climate as a better predictor of richness. Contemporaneous climate stands as the most plausible explanation for contemporaneous patterns of richness, at least over the last 11,000 yr. In Chapter two, I tested the prediction that richness of most taxa should increase with temperature in all but the warmest and driest areas. Climate warming during Pleistocene-Holocene transition led richness increases in wet areas, but richness declines in dry regions, as expected from current richness-climate relationships. A decline in small mammal species richness in Northern California since the late Pleistocene was expected from the current richness-climate relationship for this group in North America. These results contest the view that future global warming may lead to species extinction rates that would qualify as the sixth mass extinction in the history of the earth. In chapter three, I first tested the hypothesis that richness gradients mainly reflect the sum of individual species climatic tolerances. I tested this hypothesis for birds, mammals and trees native to eastern North America (ENA, where there are no major barriers to dispersal). The number of species present in any given area in ENA is usually much smaller than the number of species in the continental pool that tolerate the climatic conditions in that area. Second, I tested several explanations for patterns of unfilled potential richness. Unfilled potential richness is inconsistent with postglacial dispersal lags, climatic variability since the Last Glacial Maximum, or with biotic interactions. In contrast, unfilled richness is highly consistent with a probabilistic model of species climate occupancy. Individual species climatic tolerances is not the process generating the main current patterns of richness, nor are post-glacial dispersal lags, climatic variability since the LGM or biotic interactions. This thesis is consistent with the hypothesis that contemporaneous climate directly controls spatial patterns of richness. Generally, there seems to be little need to invoke historical processes as determinants of current gradients of richness.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2017-12-08T12:55:20Z No. of bitstreams: 1 PGEF16MA064.pdf: 123055 bytes, checksum: 5b8c73da9e2d7b658129f69b87b92d37 (MD5) / Made available in DSpace on 2017-12-08T12:55:20Z (GMT). No. of bitstreams: 1 PGEF16MA064.pdf: 123055 bytes, checksum: 5b8c73da9e2d7b658129f69b87b92d37 (MD5) Previous issue date: 2016-07-08 / FAPESC / The present study aimed to model the bioclimatic niche of Mimosa scabrella and Ilex paraguariensis and to predict the impact of climate change on potential distribution of these species. The geographic coordinates of species occurrence were extract from LABDENDRO/UDESC database, from published scientific papers, and from SpeciesLink database, from the reference Center on Environmental Information (CRIA). A total of 19 bioclimatic variables and altitude from the occurrence sites were obtained from the Wordclim database. The modelling of bioclimatic niches was performed through ten algorithms: Generalized Linear Models (GLM), Generalized Boosting Model (GBM), Generalized Additive Models (GAM), Classification trees (CTA), Artificial Neural network (ANN), BIOCLIM, Discriminant Analysis (FDA), Multivariate adaptive regression splines (MARS), Random Forests (RF) and maximum entropy (MAXENT). The fits qualities were verified trough TSS statistics, with the prediction of spatial distribution of species built from the consensus of fits with TSS > 0.85. For future predictions, a best (RCP4.5) and a worst (RCP8.5) climate change scenarios were considered in 2070, based on the fifth IPCC report. For the projections of these scenarios, the HADGEM2-ES atmospheric circulation model was used. All data analyses were conduct using R statistical program language, with the packages dismo, raster, USDM and biomod2. The results indicate that Ilex paraguariensis and Mimosa scabrella presented a phytogeographic distribution associated with the Atlantic Domain. In the worst case climate change scenario Ilex paraguariensis and Mimosa scabrella presented a reduction of 15 and 19.5% in its respective potential occurrence areas. The southern and southeastern high altitude areas, such as those located at the top of Serra Geral, Serra do Mar and Mantiqueira ranges, stood out as strategic areas for the conservation and sustainable management of these two species, since these areas present the highest values of probability of occurrence for both species in the present and in the future / O presente estudo teve como objetivo principal a modelagem do nicho bioclimatico de Mimosa scabrella e Ilex paraguariensis e a predição do impacto de mudanças climáticas sobre a distribuicao potencial das mesmas. As áreas de ocorrência foram definidas a partir das coordenadas geográficas das espécies, determinadas a partir de informações contidas no Banco de Dados do LABDENDRO/UDESC, de trabalhos publicados na literatura científica e de pontos de georreferenciamento de ocorrência do banco de dados SpeciesLink, do Centro de Referência em Informação Ambiental. Foram consideradas 19 variáveis bioclimáticas e altitude das áreas de ocorrência, obtidas a partir da base de dados do Wordclim. A modelagem dos nichos bioclimáticos foi realizada por meio de dez algoritmos: Modelos Lineares Generalizados (GLM), Generalized Boosting Model (GBM), Modelos Aditivos Generalizados (GAM), Árvores de Classificação (CTA), Rede Neural Artificial (ANN), BIOCLIM, Análises Discriminante Flexível (FDA), Multivariate adaptive regression splines (MARS), Florestas Aleatórias (RF) e Máxima Entropia (MAXENT). A qualidade dos ajustes foi verificado por meio da estatística TSS, de forma que a predição da ocorrência espacial das espécies foi realizada a partir do consenso dos ajustes com TSS > 0,85. Para predições futuras, foram considerados cenários de mudanças climáticas mais (RCP4.5) e menos otimista (RCP8.5) no ano de 2070, com base no quinto relatório do IPCC. Para as projeções destes cenários utilizou-se o modelo de circulação atmosférica HADGEM2-ES. Todos os dados foram analisados no ambiente de programação estatística R, junto com as bibliotecas USDM, dismo, raster e biomod2. Com os resultados obtidos foi possível observar que Ilex paraguariensis e Mimosa scabrella apresentam uma distribuição fitogeográfica associada ao Domínio Atlântico. No pior cenário de mudanças climáticas Ilex paraguariensis e Mimosa scabrella apresentaram uma redução de 15 e 19,5% em suas respectivas áreas de ocorrência potencial. Em se tratando de áreas estratégicas para a conservação e manejo sustentável das duas espécies, se destacaram as áreas de maior altitude na região Sul e Sudeste, como aquelas situadas no topo da Serra Geral, Serra do Mar e da Mantiqueira, por apresentarem os maiores valores de probabilidade de ocorrência para ambas as espécies, tanto no presente, quanto no futuro

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