Forest corridors maintain historical gene flow in a tiger metapopulation in the highlands of central India

Abstract

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 km 2 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.

A comparative study of the use of tiger-specific and heterologous microsatellite markers for population genetic studies of the Bengal tiger (Panthera tigris tigris)

“…The number of alleles per locus at the polymorphic loci (n = 16) ranged from three to five (average 3.625), the effective number of alleles per locus ranged from 2.000 to 3.447 (average 2.781), and the mean PIC was 0.575 (Table 2). Considering the small number of individuals in our study, we support our results by examining the mean values of H E and H O (0.675 and 0.668, respectively) of the combined panel (n=16), which are comparable with the reported mean values of H E (0.655 to 0.810) and H O (0.650 to 0.7624) in non-invasive genetic studies carried out on the Bengal tiger (Reddy et al, 2012;Gour et al, 2013;Sharma et al, 2013). We established the relatedness among the captive tigers (n = 8) using the combined panel of highly polymorphic loci and estimated the mean value of the relatedness coefficient (R = -0.143), which indicated that the selected tigers were not highly related to each other, as is mostly expected in captive individuals.…”

Biodiversity resilience in the Central Indian Highlands is contingent on maintaining and recovering landscape connectivity: the tiger as a case study

“…Over the last 300 years, the highlands lost 78 % of forest cover to agriculture and urbanization. In the past few decades, the rate at which the human footprint expanded is unparalleled (Sharma et al 2013b). Yet, this is a global priority TCL (Dinerstein et al 2007).…”

“…However, there has been a 47-70 % reduction in effective dispersal events (first-and second-generation migrants) between the Kanha-Pench source populations and the other tiger reserves such as Kanha-Melghat, Kanha-Satpura, and Pench-Melghat which are connected by agricultural areas and degraded forest corridors. Aside from the KanhaPench connection, other tiger reserves still connected through forest corridors-Satpura-Melghat, SatpuraPench-showed no significant change in gene flow (Sharma et al 2013b).…”

Livestock losses and hotspots of attack from tigers and leopards in Kanha Tiger Reserve, Central India

“…Kanha also serves as a source site for tiger and leopard populations throughout the central Indian landscape Sharma et al 2013) and is thus a priority region for minimizing human-carnivore conflict. In Kanha, tigers and leopards mainly kill cattle (Bos indicus), buffalo (Bubalus bubalis), and goats (Capra aegagrus hircus; Negi and Shukla 2010).…”