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Dutta T.,Smithsonian Conservation Biology Institute | Dutta T.,George Mason University | Sharma S.,Smithsonian Conservation Biology Institute | Sharma S.,George Mason University | And 4 more authors.
Evolutionary Applications | Year: 2013

Gene flow is a critical ecological process that must be maintained in order to counteract the detrimental effects of genetic drift in subdivided populations, with conservation benefits ranging from promoting the persistence of small populations to spreading adaptive traits in changing environments. We evaluated historical and contemporary gene flow and effective population sizes of leopards in a landscape in central India using noninvasive sampling. Despite the dramatic changes in land-use patterns in this landscape through recent times, we did not detect any signs that the leopard populations have been through a genetic bottleneck, and they appear to have maintained migration-drift equilibrium. We found that historical levels of gene flow (mean mh = 0.07) were significantly higher than contemporary levels (mean mc = 0.03), and populations with large effective population sizes (Satpura and Kanha Tiger Reserves) are the larger exporters of migrants at both timescales. The greatest decline in historical versus contemporary gene flow is between pairs of reserves that are currently not connected by forest corridors (i.e., Melghat-Pench mh- mc= 0.063; and Kanha-Satpura mh- mc= 0.054). We attribute this reduction in gene flow to accelerated fragmentation and habitat alteration in the landscape over the past few centuries, and suggest protection of forest corridors to maintain gene flow in this landscape. © 2013 The Authors.


Dutta T.,Smithsonian Conservation Biology Institute | Dutta T.,George Mason University | Sharma S.,Smithsonian Conservation Biology Institute | Sharma S.,George Mason University | And 4 more authors.
Diversity and Distributions | Year: 2013

Aim: Habitat loss and fragmentation can influence the genetic structure of biological populations. Large terrestrial predators can often avoid genetic subdivision due to fragmentation because they have high rates of dispersal-mediated gene flow. Leopards (Panthera pardus) are found in a variety of habitats and are the most widely distributed of the large and middle-sized felids. We investigated the genetic diversity and population substructure of leopards (P.p fusca) in a fragmented meta-population comprised of four populations from five protected areas and inter-connecting corridors spread over an area of 45,000 km2 in central India. Location: Kanha, Pench, Satpura and Melghat Tiger Reserves, and interconnecting corridors in the Satpura-Maikal Landscape of Central India. Methods: We collected faecal samples and used genetic methods to identify individuals, estimate the genetic variation and evaluate the patterns of genetic substructuring within this meta-population of leopards. Results: We identified 217 individual leopards using a panel of seven microsatellite loci. Leopards showed high levels of genetic diversity in all sampled populations. Spatial and non-spatial Bayesian analysis revealed at least two admixed genetic populations with indications of ongoing genetic subdivision. Genetic differentiation between populations was not explained by geographic distance. We identified nine individuals as migrants, most of which were assigned to reserves connected by corridors. Main conclusions: Our study demonstrates that the leopard, an adaptable and vagile species, can become genetically differentiated with increased habitat fragmentation. Contrary to our hypothesis of panmixia, our results indicate that although leopards in this landscape are admixed, there is genetic substructuring at both the landscape and the fine-scale level. We conclude that this is due to habitat fragmentation and corridors are of immense value in maintaining genetic connectivity in this landscape. © 2012 John Wiley & Sons Ltd.


Sharma S.,Smithsonian Conservation Biology Institute | Sharma S.,George Mason University | Dutta T.,Smithsonian Conservation Biology Institute | Dutta T.,George Mason University | And 5 more authors.
Ecology and Evolution | Year: 2013

We investigated the spatial genetic structure of the tiger meta-population in the Satpura-Maikal landscape of central India using population- and individual-based genetic clustering methods on multilocus genotypic data from 273 individuals. The Satpura-Maikal landscape is classified as a global-priority Tiger Conservation Landscape (TCL) due to its potential for providing sufficient habitat that will allow the long-term persistence of tigers. We found that the tiger meta-population in the Satpura-Maikal landscape has high genetic variation and very low genetic subdivision. Individual-based Bayesian clustering algorithms reveal two highly admixed genetic populations. We attribute this to forest connectivity and high gene flow in this landscape. However, deforestation, road widening, and mining may sever this connectivity, impede gene exchange, and further exacerbate the genetic division of tigers in central India. © 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.


Sharma S.,Smithsonian Conservation Biology Institute | Sharma S.,George Mason University | Sharma S.,Clemson University | Dutta T.,Smithsonian Conservation Biology Institute | And 6 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2013

Understanding the patterns of gene flow of an endangered species metapopulation occupying a fragmented habitat is crucial for landscape-level conservation planning and devising effective conservation strategies. Tigers (Panthera tigris) are globally endangered and their populations are highly fragmented and exist in a few isolated metapopulations across their range. We used multi-locus genotypic data from 273 individual tigers (Panthera tigris tigris) from four tiger populations of the Satpura-Maikal landscape of central India to determine whether the corridors in this landscape are functional. This 45 000 km2 landscape contains 17% of India's tiger population and 12% of its tiger habitat. We applied Bayesian and coalescent-based analyses to estimate contemporary and historical gene flow among these populations and to infer their evolutionary history. We found that the tiger metapopulation in central India has high rates of historical and contemporary gene flow. The tests for population history reveal that tigers populated central India about 10 000 years ago. Their population subdivision began about 1000 years ago and accelerated about 200 years ago owing to habitat fragmentation, leading to four spatially separated populations. These four populations have been in migration-drift equilibrium maintained by high gene flow. We found the highest rates of contemporary gene flow in populations that are connected by forest corridors. This information is highly relevant to conservation practitioners and policy makers, because deforestation, road widening and mining are imminent threats to these corridors. © 2013 The Author(s).


Dutta T.,Smithsonian Conservation Biology Institute | Sharma S.,Smithsonian Conservation Biology Institute | Maldonado J.E.,Smithsonian Conservation Biology Institute | Maldonado J.E.,Smithsonian Institution | And 2 more authors.
PLoS ONE | Year: 2015

Sloth bears (Melursus ursinus) are endemic to the Indian subcontinent. As a result of continued habitat loss and degradation over the past century, sloth bear populations have been in steady decline and now exist only in isolated or fragmented habitat across the entire range. We investigated the genetic connectivity of the sloth bear meta-population in five tiger reserves in the Satpura-Maikal landscape of central India. We used noninvasively collected fecal and hair samples to obtain genotypic information using a panel of seven polymorphic loci. Out of 194 field collected samples, we identified 55 individuals in this meta-population. We found that thismeta-population has moderate genetic variation, and is subdivided into two genetic clusters. Further, we identified five first-generationmigrants and signatures of contemporary gene flow.We found evidence of sloth bears in the corridor between the Kanha and Pench Tiger Reserves, and our results suggest that habitat connectivity and corridors play an important role inmaintaining gene flow in this meta-population. These corridors face several anthropogenic and infrastructure development threats that have the potential to sever ongoing gene flow, if policies to protect them are not put into action immediately. © 2015, Public Library of Science. All rights reserved.

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