Bonn, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Bonn, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

In this thesis, the biogeography of the centipede family Scolopendridae of the Western Ghats (WG)was studied. First, a novel limited sampling approach to identify putative Gondwanan origin wherein sampling of was confined to one of the Gondwanan fragments, i.e. the WG was developed. The results indicated that at least four genera, Scolopendra, Cormocephalus, Rhysida and Digitipes of Scolopendridae, have diversified on the drifting peninsular Indian plate, and thus might have a Gondwanan origin. Three of these genera, Cormocephalus, Scolopendra and Rhysida, might have dispersed out of India and Digitipes has remained a Gondwanan relict. Second, an integrative frame work was used to delimit species boundaries in the genus Digitipes which was characterized as an ancient, endemic and monophyletic group. A new phylogenetic hypothesis was proposed for the genus Digitipes, with eight sampled species of which three were described and five were potentially new species. Among the five potentially un-described species, three were morphologically cryptic, emphasizing the effectiveness of this approach in revealing cryptic diversity. Third, historical biogeography of wet evergreen species of WG was evaluated using the genus Digitipes from the WG. Biogeographic and divergence date estimation suggest that the southern WG was indeed a refuge for Digitipes species of the WG during Cretaceous volcanism. The dated molecular phylogeny of family Scolopendridae as well as of genus Digitipes obtained in the current study will be useful in future comparative biogeography and diversification studies in the WG.

Universiẗat, Diss., 2003--Bonn.

No description available.

One of the biggest attractions of the tropics is its stunning diversity; the origin and determinants of this diversity are amongst the most important questions in evolution and biogeography. There are two ways of looking at diversity: diversity as observed in clades on the tree of life and diversity as distributed in space. Various processes drive patterns in clades leading to a gradient of evolutionary radiations. These radiations are amongst the major contributors to Earth's biological diversity and act as good model systems to test the relative significance of processes governing macroevolutionary patterns of diversification. My research presented here revolves around one such evolutionary radiation of frogs that we uncovered from the Western Ghats, a tropical mountain system in Peninsular India. The broad aim of my thesis is to understand the causes and consequences of diversification, the primary process that drives evolutionary radiations and diversity differences in clades. The ultimate goal is to use a model system in a regional setting to explore diversification process¬es in clades against the backdrop of existing theory and ultimately paint a broader picture to further our understanding of diversity patterns in space. I have organized this thesis into six chapters. The first chapter serves as an introduction to the concepts, models and problems addressed, while chapters two to five form the crux of this thesis, and the final chapter pro¬vides a synthesis of results and directions to carry this research forward. In the first chapter, I have provided a conceptual link between diversity in Glades, evolutionary radiations and diversification and its drivers, all of which form the backbone for the following chapters. I review the potential historical processes that acted independently or in combination to give rise to one of the global biodiversity hotspots, the Western Ghats of the Indian sub-continent. I also introduce the model system, bush frogs, and provide a brief overview of their current taxonomic and systematic status. Finally, I have described the goal and questions addressed in this thesis. In chapter 2, I address the problem of delimiting lineages and provide a base for the remaining chapters 3, 4 SE 5, which form the core of this research. In this chapter, I address two major issues in biogeography. namely the 'Linnean shortfall' (the problem of undescribed lineages) and the 'Wallacean shortfall' (the lack of distribution data), and use an extensive sampling regime and a phylogenetic framework to delimit lineages. When I began my sampling, 21 lineages had been described from the Western Ghats. Three years of sampling across 13 major massifs has led to an increase in the number of the lineages to 70. These lineages were delimited using a hierarchical multi-criteria approach using a haplotype phylogenetic tree, genetic distance, geography and morphology. Lineages recovered in this study range from shallow to deep divergences and are spatially distributed from lowlands to Massif summits. Further, inclusion of geography as a variable in the hierarchical approach increased efficacy in delimiting lineages. This approach was used to establish a working hypothesis of lineages for later chapters, where I address questions related to the drivers behind the diversification of these Lineages. The goal in chapter 3 was to examine the evolutionary and biogeographic processes underlying in-situ Glade diversification in the bush frog clade at broad temporal and spatial scales. First, I examined the Glade for characteristics of an evolutionary radiation. One of the fundamental challenges in characterizing evolutionary radiations is to discern independent colonization from in-situ diversification. Phylogenetic reconstructions shows that bush frog lineages in the Western Ghats belong to two clades: a larger Glade composed of 67 lineages, with their ancestral origin centered in the Western Ghats Escarpment, and a set of three lineages with their distribution in Western Ghats, but phylogenetically nested within the Sri La.nkan bush frog Glade. The larger Western Ghats clade recovered here lends strong support for in-situ radiation of bush frogs, the origin of which can be dated to Eocene - Oligocene boundary. The bush frogs are a relatively young radiation compared to recent reports of ancient lineages and potential radiations whose origins date to the Cretaceous. Within the Western Ghats, bush frogs make up the largest vertebrate radiation, and when considered with the sister clade in Sri Lanka, constitute the largest vertebrate radiation in South Asia. These clades attain greater significance because of the limited geographical space in which the whole radiation has occurred. Temporal patterns of line-age diversification in the Western Ghats bush frog Glade show strong signatures o f an early burst, considered as one of the characteristic features of evolutionary radiations, especially adaptive radiations. Considering that a similar pattern could arise from the initial formation of geographical isolates, I tested the Glade for the role of regional biogeographic barriers in the initial diversification of the Glade. Ancestral range reconstruction showed that the initial diversification of the bush frog Glade is coincident with the Palghat Gap, a prominent geographical break in the Escarpment. Two sister clades, North and South, could be discerned, with their respective centres of origin north and south of the Palghat Gap. There was limited dispersal across the gap and a number of these dispersal events resulted in diversification in the adjoining regions. These results, for the first time, lend strong evidence for the biogeographic significance of the Palghat gap for amphibian diversification. The discovery of the North and South sister-clades, apart from elucidating the significance of Palghat gap as a barrier in the initial diversification of the Glade, provided a unique setting to gain further insights into diversification processes. using the sister clades. The South Glade shows support for the models of early burst and subsequent diversity-dependent decline, while the North Glade did not differ from a constant pure-birth model of diversification. The sister clades also showed strong differences in the number of lineages and in the ecological and morphological diversity of component lineages. In terms of the ecological diversity of the clades, the lineages in the South Glade are predominantly closed canopy dwellers and occupy all the vertical strata of the forest from understorey to canopy. In contrast, the North Glade is characterized by the absence of canopy lineages and also in the relative increase in the number of open canopy lineages. I excluded area as a causal factor, considering the relatively smaller area of the region of the South Glade, south of Palghat Gap, compared to the North Glade. Taken together, an early burst in lineage diversification, high species richness and Glade-level endemism, narrow geographical range of the Glade, restriction of canopy lineages to this Glade and persistence of a historical rainforest refugium in this area suggested a potential role for ecological opportunity in the adaptive radiation of the South Glade. The results from Chapter 3 brought out the strong contrast in the ecological diversity of extant lineages among the bush frog sister clades occurring in this region. One major ecological pattern is the predominance of closed canopy lineages in the South Blade, while the North Glade was characterized by relatively more open canopy lineages. However, what caused the origin of open canopy lineages and the predominance of such lineages in the North Glade was not known. In chapter 4, I explore whether signatures of the global climate mediated emergence of open canopy biomes can be discerned in the habitat shift and in the observed contrast in ecological disparity between the sister clades. The results show multiple habitat shifts among bush frog lineages in the Western Ghats, with a strong contrast between the sister clades; the North Glade exhibited a greater number of habitat shifts compared to the South Blade. A unique shift to the bamboo reed Ochlandra could be discerned in the South Glade. The study provided the first evidence for independent shifts to grass associated habitats among bush frogs and frogs in general. Examination of ecomorphology brought out further interesting insights. For the same body size, lineages occurring in grass-associated habitats, Oehiandra reeds and grasslands have independently evolved smaller hind limbs compared to lineages that occur in the forest and shrub-land habitats. This convergence in limb-size and a. pattern of reduced limb-size provides support for the adaptive nature of this trait in relation to grass associated habitat shifts among bush frog lineages. Examination of this morphological trait in time, using disparity through time plots, showed high disparity within the North Glade as expected from the patterns of greater habitat shift. These results lend support for orbitally forced habitat dynamics as a driver for the intra-cladal patterns of ecological disparity in bush frog sister clades. Researchers in the past have largely tested evolutionary radiations for adapt signatures under the assumption of ecological opportunity. One of the drawbacks of temporal models of diversification is the exclusion of geography. Mountain systems slid-the -Western Ghats provide an ideal setting to explore diversification in space. In chapter took a biogeographic approach and tested the relative importance of Quaternary glaciatic ecological gradients and Earth related processes on the spatial patterns of lineage and s dada! diversification in a mountain setting. This was done using a set of a-priori predict', on the phylogenetic, spatial and temporal patterns of lineage diversification based on geological and climatic history of the Western ghats. These were tested using sister-lines and latitudinal and elevational range data obtained from field sampling across 13 mass Independent methods were used to test for the alternative processes. A majority of recer diverged bush frog sister - lineages were characterized by non-overlapping geographi ranges, and were isolated on adjacent massifs, indicating allopatric speciation eves Independent transitions along elevational gradients among sub-clades during the Mioc' lend support for diversification mediated by the uplift of the escarpment. In-situ diversificat in the montane zone of the two highest massifs shows the effect of past - climate media forest-grassland dynamics, but divergence times lend less support for the role of Quatern glaciations. These results highlight the important role of geological processes in the line; diversification of bush frogs. By examining patterns in a large radiation, I was also able bring out the temporal and spatial significance of different processes. Diversification in s Glades shows that recent non-adaptive processes have masked the effect of initial adapt radiation. Based on these findings, we recognize the massifs in this Escarpment as cent of lineage diversification and generators of diversity and the lowland and medium elevat habitats in the southern Western Ghats, with deeply divergent lineages, as museums. Through this research, I have provided a number of insights — many for the first time — into the macroevolutionary patterns and historical processes behind this large vertebrate radiation in a global biodiversity hotspot. The thesis also sets a foundation to explore the processes driving ecological and biogeographic patterns — species richness, endemism and community assembly — in space.

No description available.

This study incorporated a community based assessment with a focus on community based tourism in Kalache and Hulgol, India. Kalache and Hulgol are two agrarian based communities located in the environmentally significant region of the Western Ghats. Each of these communities has considered community based tourism as a means to reduce urban youth outmigration, to diversify economic resources, and to encourage the empowerment of women. The primary goals of this study were to understand the community issues and objectives, to determine the level of support for tourism development, to determine participant attitudes toward tourism, and to determine the obstacles to tourism development. The findings of this project address the complexity of operating in the tourism industry, the impacts of tourism, and the use of community based tourism models in support of sustainable tourism.

It has been more than two centuries since the latitudinal pattern of increase in taxonomic richness from poles to equator was first documented. After two centuries of research, and with more than two dozen hypotheses proposed, an understanding of the mechanisms underlying this pattern and their relative importance remains incomplete. Factors such as evolutionary history, area and latitude associated variables such as temperature, solar energy, climatic stability and seasonality are known to influence species richness by affecting geographic range size and location over ecological and evolutionary time. Understanding the forces that affect geographic range size is, therefore, integral to our understanding of latitudinal patterns in species richness. Using woody plants as a study system, my dissertation deciphers the latitudinal pattern, if any, in species richness within the evergreen forests of the Western Ghats. These wet evergreen forests form an evolutionarily distinct biogeographic zone, which has remained isolated from its counterparts. This has resulted in a high percentage of endemism among the evergreen woody plants and, therefore, the global geographic ranges of most of these plants are restricted within the boundaries of the Western Ghats. The first main objective of this dissertation is to understand the determinants of geographic range size in the evergreen woody plants of the Western Ghats. Further, the Western Ghats are characterized by a sharp climatic gradient in temperature and rainfall seasonality that is not correlated with mean annual temperature or annual rainfall. This allows a direct test of the hypotheses and predictions that are based on climatic seasonality, without the confounding effect of other climatic correlates of latitude. Therefore, the second main objective of this dissertation is to understand the mechanisms underlying latitudinal patterns in species richness of evergreen woody plants in the Western Ghats. Regional species richness is an outcome of two factors- local species richness of each location within the region and turnover in species composition among the locations, which in turn are a result of patterns in range size, range location and range overlap. To address these two objectives, I first test the effect of climatic niche of a species in determining geographic range size and then examine the effect of latitude associated climatic seasonality on range location and range overlap. Next, I link the observed pattern in range geometry to latitudinal patterns in species turnover and finally to latitudinal patterns in species richness. While the first part of my dissertation study deals with factors that generate spatial variation in species richness, the second part deals with the factors underlying spatial variation in species composition. Environmental heterogeneity and dispersal are considered the most important determinants of species turnover i.e. change in species composition. However, their relative importance in structuring in diverse plant communities within tropical regions across different scales is poorly understood. Hence, the third objective of this dissertation is to understand the processes that influence change in species composition of woody plants within the Western Ghats. Geographic range size and population size are important attributes of species rarity, which are directly linked to their extinction risk. Hence, data on distribution and population status of species can help us focus our efforts on those species that require conservation attention. This is achieved through carrying out species threat assessments based on attributes such as range and population size and then assigning then to a threat category. A majority of species endemic to the Western Ghats have not yet been assessed, largely due to lack of data on their population and distribution status. Therefore, the fourth and the final part of my dissertation explores the application of information on species range size and abundance in prioritizing species for conservation. To address these objectives, I sampled the wet evergreen forests of the Western Ghats along a series of locations distributed across its entire latitudinal gradient. Based on 156 plots, covering a latitudinal gradient of more than 1200 km and comprising of more than 20,000 occurrence locations belonging to more than 450 species of woody plants, I derived quantitative estimates of latitudinal gradients in range size, local and regional richness as well as species turnover. I used a combination of statistical and simulation approaches to discern the mechanisms underlying large-scale pattern in species ranges, richness and turnover. My dissertation is structured as follows.

Macroecology is the study of relationships between organisms and the environment at large spatial and temporal scales. This field of research examines patterns in species abundance, distribution and diversity. Understanding patterns in species distribution and richness can contribute significantly to our knowledge of community assembly and macroecological patterns, as well as to the effective conservation of threatened species and habitats. Although there have been a plethora of studies on birds in India over the years, there is a critical need to accurately delineate species distributions and understand patterns of richness. The focus of this study was to understand the factors (abiotic and biotic) that influence the distribution and composition of bird species in the Western Ghats, as well as to explore patterns in their geographic range sizes. The objectives of this study were addressed at the scale of the entire Western Ghats using a combination of field surveys, secondary data collection and species distribution modeling. The specific approaches to address these questions and the findings are outlined below. Chapter 2: Bird species in the Western Ghats – Patterns in composition and richness Fine-scale data on species presence and abundance are essential for exploring patterns in species distribution and richness. Despite the fact that birds have been extensively studied in the Western Ghats, systematic data collection and compilation of information over the entire mountain range has not been carried out, especially for the purpose of testing macroecological questions. This chapter describes patterns in bird species presence, abundance, composition and richness within the Western Ghats. The study area, site selection protocol and the sampling technique have also been described in detail. This dataset establishes a baseline of information about birds in the Western Ghats and subsets of this larger dataset will be used to address various questions in the following chapters. Chapter 3: Predicting bird species distribution in the Western Ghats Detailed knowledge of species’ ecological and geographical distributions is fundamental for conservation, as well as for understanding ecological and evolutionary determinants of spatial patterns of biodiversity. However, occurrence data for a vast majority of species are sparse, resulting in information about species distributions that is inadequate for many purposes. Species distribution models attempt to provide detailed predictions of distributions by relating presence or abundance of species to environmental predictors. In this chapter, we describe the usage of Maxent, a species distribution modelling technique based on presence-only data, to predict the distributions of bird species within the Western Ghats. For this purpose, we put together primary locations of bird species presence along with a published dataset. Using a number of important environmental layers, predicted species distribution maps were derived for 98 bird species, including 13 endemics, in the Western Ghats. Additionally, we calculated predicted range sizes for each of these species and obtained percentage contributions of important environmental predictors to each species’ distribution. This is the first study to develop species distribution models for bird species within the Western Ghats. Chapter 4: Patterns of range size among bird species Understanding large-scale patterns of variation in species geographic range size is fundamental to questions in macroecology and conservation biology. In general, range is believed to be influenced by a combination of environmental factors, evolutionary history and biotic interactions, mediated by species specific traits. These patterns need to be examined even for well-studied taxa like birds, especially within biodiversity hotspots faced by persistent degradation due to anthropogenic activities such as the Western Ghats. In this chapter, we use a dataset of 98 bird species within the Western Ghats to examine trends in range sizes, measured as latitudinal extent of occurrence and predicted range size from species distribution models. We show a significant relationship between latitude and range size for these bird species, supporting Rapoport’s rule. As far as we know, this relationship has never been tested at such low latitudes for birds. We also find that species traits such as body size, mean abundance and diet do not seem to show any discernable effect on patterns of range size. Additionally, we found that widely-used bird species range maps (in this case, from BirdLife International) are inaccurate representations of species ranges in comparison to the predicted species distribution maps that were derived in the previous chapter. We quantitatively demonstrated that these expert-drawn maps need to re-evaluated, especially since they are used to make conservation decisions. This is the first study to quantify species range sizes of birds within the Western Ghats and assess such range maps that are used to determine conservation status of species. Chapter 5: Environmental predictors of bird species distribution One of the major goals in ecology is to understand patterns and processes that determine species diversity. The drivers of global species richness gradients have been studied, especially in the case of birds, in terms of contemporary and historical factors. Such broad scale processes may not always reflect the processes affecting richness and distribution at smaller scales. Therefore, understanding the factors that influence individual species distributions is the first step towards this larger goal. In this chapter, we examined the environmental predictors that contributed to the predicted distribution of bird species observed in the Western Ghats, using the variable importance contribution values derived in Chapter 3. We found that a large proportion of the 98 bird species studied were influenced by normalized differential vegetation index, annual precipitation and elevation. The predictors did not differ among birds of different diet guilds and body size classes. Using Prinicipal components analysis, we observed that all 98 bird species are spread out across the environmental ordination space depicted by the PC axes 1 and 2. These axes are governed by measures of habitat heterogeneity and water-energy related variables, consistent with other tropical studies. The insectivorous guild seemed to occupy a variety of environmental niches across this space and other guilds seemed to be nested within the insectivorous guild. Similarly, larger sized birds were spread across the entire environmental ordination space, with species of smaller sizes nested within. This is the first step in trying to understand environmental predictors acting on birds in the Western Ghats. Further detailed studies need to be carried out to come to definite conclusions. Chapter 6: Relative roles of floristics and vegetation structure on bird species composition On the basis of the hierarchical model of habitat selection, it is known that birds select suitable habitats based on vegetation structure (physiognomy) at coarse biogeographic scales, and plant species composition (floristics) at more local scales. This chapter examines the relative influence of tree species composition and vegetation structure on bird species composition in the Western Ghats. These relationships were specifically assessed across the entire Western Ghats, within regions of the Western Ghats as well as within specific forest types. We found that floristics had a strong association with bird species composition across the Western Ghats and within evergreen and mixed deciduous habitat types. This association seems to be independent of the structural variation in the region. There was a decrease in association strength from the southern to the northern Western Ghats, in terms of both floristics and structure. We did not find an association between vegetation structure and insectivore composition, whereas phytophage composition did show a stronger association with floristics than structure. This is the first study at the scale of the entire Western Ghats to test the relative roles of floristics and vegetation structure. Taken as a whole, this dissertation examines large-scale macroecological questions regarding species distribution, range size and patterns of composition using primary data at the scale of the Western Ghats. The findings of this study have established a foundation that will help further our understanding of species distribution and richness in the Western Ghats, and aid in the decision making for conservation strategies in the future.