Diversos aspectos metabólicos e comportamentais possuem uma estreita relação com as condições do ambiente, havendo um compromisso entre as condições naturais e a dinâmica de modificações sobre os organismos. Devido ao grande índice de degradação ambiental proveniente da atividade humana nos últimos tempos, populações de anfíbios têm sido particularmente mais afetadas devido a sua alta sensibilidade a alterações ambientais. Em uma paisagem fragmentada, a manutenção de metapopulações viáveis é um importante fator a persistência das populações. Dentro deste contexto, este estudo propõe investigar as relações entre a fragmentação florestal e habilidade das algumas espécies de anuros para se deslocar entre os fragmentos, ou entre estes e corpos d\'água. Assim, realizamos comparações, fisiológicas e comportamentais intra e interespecífica de espécies de anuros residentes em paisagens contínuas e fragmentadas em duas localidades da Floresta Atlântica, com base em suas características morfológicas. De acordo com nossos resultados, as diferenças ambientais entre as paisagens estão relacionadas com as diferenças morfofisiológicas entre as espécies. / In the last few decades, human activity has changed environmental condition, resulting in amphibian populations decline all around the world. In this study we analyze the relationships between forest fragmentation and the ability of some frog species to move between forest fragments or between fragments and breeding sites. Our study focus relies on anuran locomotor performance and supporting physiology, and the relationship between these traits and resistance to forest fragmentation. We compare morphological, physiological and behavioral traits between populations of anurans species living in different landscapes (continuous or fragmented) of two sites in the Atlantic Forest. According to our data, differences in environmental conditions of landscape are related to morpho-physiological traits. This relationship, however, depends on the site of the Atlantic Forest and also varies between species.

A biodiversidade dos rios brasileiros encontra-se sob severa ameaça, em razão da fragmentação e perda de hábitat que os barramentos representam. Até o presente, os aproveitamentos hidrelétricos têm seu licenciamento ambiental condicionado a análises de impacto locais, sem avaliação dos impactos cumulativos de múltiplas barragens em uma bacia hidrográfica, com relação à conservação da diversidade da ictiofauna. Estudos anteriores para subsídio de licenciamento de múltiplas barragens na bacia Taquari-Antas (RS) propuseram cenários alternativos de conservação (número e posição de barragens), quando ainda não havia métricas de conectividade dendrítica desenvolvidas. Entre os problemas identificados naqueles estudos figuram a quantificação dos efeitos cumulativos das barreiras sobre a conectividade da bacia, o estabelecimento de áreas prioritárias para conservação e a influência do número e da posição das barreiras na conservação da biodiversidade aquática em uma bacia. Avaliamos a aplicação de conectividade para mensuração de impactos cumulativos de fragmentação de bacias hidrográficas através de índices de conectividade dendrítica recentemente propostos. Propomos um método genérico e replicável para analisar quantitativamente os efeitos de sucessivos barramentos em relação à conectividade dos hábitats aquáticos em processos de migração e dispersão de peixes em bacias hidrográficas. Utilizamos simulações de cenários de múltiplos barramentos para a avaliação. Propomos também uma sistematização para a simulação de múltiplos barramentos. Além disso, hierarquizamos áreas para conservação por conectividade, aplicamos as novas métricas de conectividade a estudos anteriores e demonstramos casos de cenários de alta conectividade com outras implicações na conservação. Discutimos o amadurecimento do método para aplicação em licenciamento ambiental e planejamento de conservação, bem como limitações atuais e perspectivas para trabalhos futuros. / Biodiversity of Brazilian rivers is nowadays seriously threatened due to fragmentation and habitat loss that impoundments represent. Up to now, hydroelectric power plants have their environmental licensing processes conditioned to local impact analysis, with no evaluation of cumulative impacts of multiple dams in a watershed landscape on the conservation of the integrity of ichthyofauna. Former studies for supporting environmental licensing processes of multiple hydroelectric dams in the Taquaria-Antas basin (RS, Brasil) proposed alternative conservation scenarios (number and position of barriers), in a time when there were no dendritic connectivity metrics developed. Among the problems identified at that time, we point quantification of cumulative effects of multiple barriers on the drainage connectivity, detecting prioritary areas for conservation and detecting the influence of the number and position of the barriers in the catchment for best conservation of aquatic biodiversity. We evaluated the application of connectivity for quantifying the impacts of fragmentation in hydrographic basins through recently proposed indexes. We proposed a replicable and generic method for quantifying the effects of successive impoundments in relation to aquatic habitat connectivity in ecological processes of migration and dispersal of fishes in hydrographic basins. We used multiple barriers scenarios simulation in order to perform the assessments. We also propose a way of systematizing multiple barriers simulations. Moreover, we rank areas for conservation by connectivity, apply the new connectivity metrics on former studies and demonstrate cases of high connectivity scenarios with other implications on conservation. We discuss maturing the method for application on environmental licensing and conservation planning as well as current limitations and perspectives for future studies.

Globally, habitat fragmentation has had a major impact on the conservation and management of many species and is one of the primary causes of species extinction. Habitat fragmentation is loosely defined as a process in which a continuous habitat is reduced to smaller, disconnected patches as the result of habitat loss, restriction of migration or the construction of barriers to movement. Aquatic systems are particularly vulnerable to habitat fragmentation, and today an estimated 48% of rivers are fragmented worldwide. My dissertation evaluates how habitat fragmentation has influenced the populations of four different species of fish in the Lake Champlain basin. In chapter 1 I summarize the current state of habitat fragmentation research, I broadly describe habitat fragmentation, review how habitat fragmentation pertains to population genetics, and describe the legacy of habitat fragmentation in the Lake Champlain basin. In chapters 2, 3 and 4 I evaluate and discuss the impact of nine lake causeways on the population structure of slimy sculpin (Cottus cognatus), rainbow smelt (Osmerus mordax), and lake whitefish (Coregonus clupeaformis). The genetic effects of causeways are limited. However, causeways appear to have had a significant influence on rainbow smelt demographics, and the genetic structure observed in lake whitefish may be a product of reduced effective population size resulted from commercial harvest in the late 1800s. In chapter 5 I evaluate how the basin-wide population of tessellated darters (Etheostoma olmstedi) is naturally structured throughout Lake Champlain and three different major tributaries and evaluates the effect that different types of habitat fragmentation (dams, causeways, and natural fall lines) have on tessellated darter populations. Tessellated darters appear to be highly structured by river drainage but not by dams, causeways or fall lines. My dissertation highlights how comparative population genetic studies can be used to identify patterns of isolation within large populations. My results stress the value of reporting both the presence and absence of barrier induced population sub-structuring.

The gliding petaurids are small sized arboreal and nocturnal marsupials restricted to Australia and the New Guinean region. They have suffered range contractions since European settlement, and most of the species are of conservation concern, either nationally or at a state level. This study applied molecular approaches to investigate several questions involving Petaurus species which may provide valuable insights for their conservation and management of species. The objectives of this study included an examination of phylogenetic and evolutionary relationships among Petaurus species, an assessment of phylogeographic structure within P. breviceps and an investigation of genetic diversity, social structure and mating system of P. breviceps in fragmented habitats. A broad molecular systematics study of the genus Petaurus was first undertaken. Two mitochondrial genes (ND2 and ND4) and a nuclear gene marker (ω-globin) were screened for sequence variation in samples obtained from across the distribution of petaurid species, including Australia, New Guinea and its surrounding islands. Phylogenetic analyses confirmed the monophyly of the genus Petaurus and revealed that, with the exception of P. gracilis, the currently recognised species were associated with divergent mtDNA clades. It also revealed considerable mtDNA diversity within the widely distributed species P. breviceps. The existence of at least seven distinct and divergent mtDNA lineages within P. breviceps was supported, with two lineages located in Australia and at least five lineages in New Guinea. However, the distribution of these evolutionary lineages did not correspond with current morphological subspecies boundaries. Analyses of ω-globin sequence provided support for a number of these distinct populations, suggesting the possible presence of cryptic species within P. breviceps. Molecular analyses also suggested that squirrel gliders, P. norfolcensis, may occur in both South Australia and the Northern Territory, extending the current known range of the species. The presence of P. norfolcensis in SA was further verified by examining museum skins. Population structure and current pattern of gene flow within P. breviceps in Australia was examined further to elucidate phylogeographic structure within the species, and explore potential causes of geographic variation. Evidence for significant phylogeographic structuring across the range of the species in Australia was provided from population genetic (AMOVA) and phylogenetic analyses of both mitochondrial DNA and the ω-globin gene. In particular, there was evidence for the existence of two divergent clades that were distributed over distinct geographical regions. Divergence dates calculated for the two major mtDNA clades suggested that environment and climate changes which occurred during the Pliocene may have facilitated this diversification. Habitat fragmentation is generally considered to be a major factor threatening the viability of forest dependent species such as gliders. Effects of habitat fragmentation were therefore investigated in P. breviceps in the highly disturbed landscape of southeastern South Australia. Genetic mating system and social structure of the species in these fragmented habitats was explored in 13 populations, using nine polymorphic microsatellite loci. Social groups consisted of two to seven gliders, and these were often close relatives, including parents with their offspring. Parentage analyses provided some evidence for a polygamous mating system, with a number of males found to have fathered offspring from multiple female partners. Some direct evidence of inbreeding was also found within a small isolated patch. Genetic diversity within P. breviceps populations was moderate compared to the range reported in other marsupial species. Population structure analyses indicated that gene flow between some patches was restricted. Small patches surrounded by a matrix of pine were more likely to show inbreeding and potentially suffer from inbreeding depression, although further data are required to verify this result. Overall, results suggest that, although the species is still present in these small and isolated patches, it may face threats from a lack of dispersal and inbreeding. Maintaining the size of patches and establishing corridors between isolated populations needs to be considered in conservation and management of species in these fragmented habitats. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1295224 / Thesis (Ph.D.) -- School of Earth and Enviromental Sciences, 2007

The impact of habitat fragmentation and the success of habitat restoration were studied through a multi-taxonomic approach. The response to landscape structure and/or habitat quality of three taxonomic groups was explored, in (semi-)natural habitats. The three taxonomic groups were complementary, both in terms of their specific life history traits and their place in the food chain. We considered autotrophic species (vascular plants), herbivores (butterflies) and predators (spiders). Life-history traits and species specialization for target habitat were used to refine the analysis. Target habitat was a complex of wet heathlands, poor fens and bogs. Patches of this complex of habitats were sampled on two high plateaus in the Belgian Ardenne, the Plateau de Saint-Hubert and the Plateau des Tailles. Over the last 250 years, two jointly acting habitat dynamics were observed in these areas: a loss of area (and connectivity) on the one hand but also the creation of new habitat patches. It is precisely this double dynamics that enabled us to analyze and develop concepts linked to the response of species faced with spatio-temporal modifications of their habitat. Specifically, in this work we focused on the comprehension of two unbalanced situations, affecting the relationships between species richness and patch characteristics. A first unbalanced situation, the extinction debt, was observed for vascular plant communities. On the opposite, a colonization credit, the second unbalanced situation, was noted for butterflies and seemed to mainly affect specialist species. Specialist species of the three taxonomic groups showed relatively contrasted responses compared to generalist species. However, the life-history traits we studied only slightly influenced the response of species at the community level, excepted for pioneer communities in habitat patches less than 5 years old.

Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. There is an urgent need of understanding how these species losses affect the ecological structure and functioning of our ecosystems. Ecological communities exist in a landscape but the spatial aspects of community dynamics have until recently to large extent been ignored. However, the community’s response to species losses is likely to depend on both the structure of the local community as well as its interactions with surrounding communities. Also the characteristics of the species going extinct do affect how the community can cope with species loss. The overall goal of the present work has been to investigate how both local and regional processes affect ecosystem stability, in the context of preserved biodiversity and maintained ecosystem functioning. The focus is particularly on how these processes effects ecosystem’s response to species loss. To accomplish this goal I have formulated and analyzed mathematical models of ecological communities. We start by analyzing the local processes (Paper I and II) and continue by adding the regional processes (Paper III, IV and V). In Paper I we analyze dynamical models of ecological communities of different complexity (connectance) to investigate how the structure of the communities affects their resistance to species loss. We also investigate how the resistance is affected by the characteristics, like trophic level and connectivity, of the initially lost species. We find that complex communities are more resistant to species loss than simple communities. The loss of species at low trophic levels and/or with high connectivity (many links to other species) triggers, on average, the highest number of secondary extinctions. We also investigate the structure of the post-extinction community. Moreover, we compare our dynamical analysis with results from topological analysis to evaluate the importance of incorporating dynamics when assessing the risk and extent of cascading extinctions. The characteristics of a species, like its trophic position and connectivity (number of ingoing and outgoing trophic links) will affect the consequences of its loss as well as its own vulnerability to secondary extinction. In Paper II we characterize the species according to their trophic/ecological uniqueness, a new measure of species characteristic we develop in this paper. A species that has no prey or predators in common with any other species in the community will have a high tropic uniqueness. Here we examine the effect of secondary extinctions on an ecological community’s trophic diversity, the range of different trophic roles played by the species in a community. We find that secondary extinctions cause loss of trophic diversity greater than expected from chance. This occurs because more tropically unique species are more vulnerable to secondary extinctions. In Paper III, IV and V we expand the analysis to also include the spatial dimension. Paper III is a book chapter discussing spatial aspects of food webs. In Paper IV we analyze how metacommunities (a set of local communities in the landscape connected by species dispersal) respond to species loss and how this response is affected by the structure of the local communities and the number of patches in the metacommunity. We find that the inclusion of space reduces the risk of global and local extinctions and that lowly connected communities are more sensitive to species loss. In Paper V we investigate how the trophic structure of the local communities, the spatial structure of the landscape and the dispersal patterns of species affect the risk of local extinctions in the metacommunity. We find that the pattern of dispersal can have large effects on local diversity. Dispersal rate as well as dispersal distance are important: low dispersal rates and localized dispersal decrease the risk of local and global extinctions while high dispersal rates and global dispersal increase the risk. We also show that the structure of the local communities plays a significant role for the effects of dispersal on the dynamics of the metacommunity. The species that are most affected by the introduction of the spatial dimension are the top predators.

The European red click beetle, Elater ferrugineus L., is associated with wood mould in old hollow deciduous tree. As a result of severe habitat fragmentation caused by human disturbance, it is threatened throughout its distribution range. A new odour-based trapping method, which is very efficient in attracting males, was used in the present study to relate the occurrence of E. ferrugineus to the density of deciduous trees using a recently completed regional survey recording >120, 000 deciduous trees. Results showed that the occurrence of E. ferrugineus increased with increasing amount of large hollow and large non-hollow trees in the surrounding landscape. Quercus robur was found as an important substrate for E. ferrugineus and two groups of tree species (Carpinus betulus, Fagus sylvatica, Ulmus glabra, vs. Acer platanoides, Aesculus hippocastanum, Fraxinus excelsior and Tilia cordata) could be a complement to the existence of Quercus in sustaining the beetle’s population. E. ferrugineus responded to the density of Quercus at two different spatial scales, 327 m and 4658 m, suggesting that a multi-scale approach is important for studying the species. In conclusion, for conservation management, priority should be given to Quercus, and also to all deciduous trees in the genera listed above, regardless of the tree quality. The response showed by E. ferrugineus on the amount of substrate at two different scales indicates that using multi-scale approach in studying this particular species is the better option as single-scale approach may result in poor decision support.

Habitat degradation by humans has been the main reason for the decline in numbers of P. floridanus, the only mammal indigenous to the state of Florida, in the past century. The mouse inhabits what remains of scrub and sandhill associations, which are characterized by patches of sandy soils within a more mesic landscape. It has long been accepted that small populations are more prone to decline and extinction than are larger ones as a result of environmental fluctuations. I hypothesized that the demography of a population of P. floridanus would be affected by a restriction in numbers through habitat patch size in a deterministic way, even without any environmental effects. I also examined dispersal and looked for evidence of metapopulation dynamics. Mark-recapture data were collected from ten scrub fragments in Lake Wales Ridge State Forest, Polk County, FL, ranging in size from 0.5 to 170 ha. Program MARK was used to model survival, recruitment and population growth rate of P. floridanus as a function of habitat patch size and to evaluate temporary migration patterns. Recruitment was positively associated with patch size, but contrary to expectations survival and population growth were negatively associated with patch size. Results suggested that survival was negatively affected by ear tagging, although this effect was temporary. Evidence of migration was found, but would probably have been greater if trapping had been continued until after peak reproduction, when juveniles tend to disperse in search of resources. The degree of interbreeding among patches can only be determined with the help of genetic analyses. Microsatellites have become useful in analyses at the population level because of their high degree of variability. Future research including genetic analyses is recommended to evaluate the importance of gene flow among subgroups to demography and the viability of the study population.

I studied a small, enigmatic, and imperiled black bear population in south-central Florida from 2004 - 2006. Annual home ranges of males (96.0 km2) were larger than those of females (32.2 km2). Female home ranges were smaller in winter than in summer or fall. At the landscape scale, bears selected forests, scrub, and citrus, but avoided urban areas. At the home range scale, bears selected bay swamp and hardwood hammock, but avoided urban areas and grassland. Bears selected bay swamp in winter, forests and scrub in summer, and forests, scrub, and marsh in fall. The bear’s diverse diet included citrus fruit. Important foods were acorn, saw palmetto fruit, and Florida carpenter ant. The local landscape is dominated by agriculture on private lands, as opposed to large contiguous forests on public land elsewhere in Florida black bear range. Mean patch size of forests was smaller, while edge density, diversity, and evenness were higher in south-central Florida than elsewhere in the state. Diversity of forest habitat may partially account for the persistence of the black bear in this fragmented landscape. Managers should encourage private landowners to adopt practices that promote bear habitat, and focus on habitat diversity, road crossings, and statewide metapopulation structure.

Habitat fragmentation potentiates biodiversity loss worldwide. Species preservation requires an integrated understanding of wildlife-habitat relationships; however, responses to habitat fragmentation may vary considerably as a function of the species ecological flexibility and the unique attributes of each fragment habitat. In this dissertation, I explore the behavioural and health ecology of an ecologically flexible primate, the ringtailed lemur (Lemur catta), occupying forest fragments in south-central Madagascar that differ in isolation, degree of anthropogenic pressure, and L. catta food resource structure. Anja Special Reserve is a 34 ha rocky-outcrop forest fragment that is highly isolated from other forests containing L. catta. L. catta in this reserve have access to abundant food and water resources year-round due to the introduction of non-native fruit trees and the construction of an artificial lake adjacent the reserve, which support a population density of L. catta (6.6 lemurs/ha) that is higher than at any other site in which the species has been studied. In comparison, the Tsaranoro Valley forest is a 53 ha rocky-outcrop forest fragment that is surrounded by a matrix of grassy savannah and a few anthropogenic crops. While land clearing is pronounced in the valley, a few fragments remain within range for L. catta dispersal. L. catta in this fragment have limited access to introduced or anthropogenic resources and the population density (1.13 lemurs/ha) is one-sixth that at Anja. During the late dry season of 2010 and mid- to late-wet season of 2011, I collected continuous time focal animal data to examine behavioural patterns related to habitat use (ranging, matrix use, terrestriality), activity budgets, and feeding ecology of L. catta in each fragment. In addition, I examined two health parameters, stress and endoparasitism, through the collection of fecal samples from focal individuals. I compared these variables between and within populations to examine the potential impacts of habitat fragmentation on an ecologically adaptable primate. L. catta at Anja depended on smaller home range areas and a focused diet consisting largely of introduced food resources, and correspondingly exhibited lower energy expenditure, while spending more time engaging in rest and social acitivities when compared with the Tsaranoro lemurs. In comparison, L. catta at Tsaranoro occupied large home ranges, traveled greater distances to forage in the matrix habitat surrounding the fragment, and exhibited a more broad-based dietary strategy that contained few introduced or anthropogenic resources. From a health perspective, L. catta at Anja exhibited higher stress levels throughout the study period, while L. catta at Tsaranoro exhibited a greater prevalence of endoparasites, which may be reflective of differences in the social pressures and ranging patterns of L. catta between the two fragments, respectively. These results illustrate differences in the quality of the habitats and the potential fitness consequences that the L. catta populations must cope with, with important implications regarding the long-term suitability of these fragments for sustaining these populations. Such information is integral when assessing the viability of wildlife populations in degraded landscapes and should be a primary consideration for wildlife managers in biodiversity conservation. / Graduate / 0327 / 0329 / denisegabrie@gmail.com