IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Yumnam, B. | |
| Evaluation of population structure of tigers (_Panthera tigris_) in central India using genetic markers | |
| 2014 Full Book | |
In the present study, I investigated patterns of spatial genetic structuring to identify habitat corridors for gene flow between populations within the fragmented tiger habitats in Central India. I wanted to explore the relationships between differential tiger densities and patchy habitat connectivity among source populations to understand metapopulation structure and gene flow across this fragmented human-dominated landscape. This study explores a strategy that utilizes extensive landscape-scale noninvasive genetic sampling and statistical assignment methods to detect population genetic structuring and determine which populations are exchanging migrants. I identified 169 individuals across seven tiger reserves in the Central Indian Landscape during 2006 to 2011 from the combined 257 scat and 17 tissue dataset for tigers by using a panel of eleven autosomal microsatellite loci. Genetic diversity was high across the population with a high mean number of alleles (9.1 ñ 2.2) and high heterozygosity, with similar estimates for expected (75.4% ñ 3.9) and observed (70.1% ñ 5.9) values. Assessment of population structuring using multidimensional principal coordinate analysis (PCoA) and a model-based Bayesian clustering of individual microsatellite genotypes (STRUCTURE) showed the seven tiger populations in the study area were grouped into four genetic clusters, viz. (i) Bandhavgarh; (ii) Melghat-Satpura-Tadoba; (iii) Pench; (iv) Kanha, Achanakmar and individuals from the Pench-Kanha corridor. Except for Bandhavgarh which formed an isolated genetic cluster, the other three population clusters had some degree of population mixing. Next, I used the four population clusters previously identified by the Bayesian individual based method above to detect gene flow (or migration) patterns between population units. I detected a total of seventeen individuals with putative immigrant ancestry, representing almost 10% (17 out of 169) of the total sampled individuals in the area. Of these, five individuals represented by four males and a female were identified as first generation migrants. The remaining twelve individuals had assignment patterns suggestive of admixed ancestry. The highest number of migrants was observed between the Kanha and Pench localities, where four first generation migrants and seven likely admixed individuals were detected. The above pattern of migration events was corroborated by estimation of migration rates, which showed low levels of contemporary gene flow in the area. |
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