Why the Indian Subcontinent Holds the Key to Global Tiger Recovery

Samrat Mondol,Uma Ramakrishnan,K Ullas Karanth,Dmitri A Petrov

doi:10.1371/journal.pgen.1000585

Abstract

With only ∼3,000 wild individuals surviving restricted to just 7% of their historical range, tigers are now a globally threatened species. Therefore, conservation efforts must prioritize regions that harbor more tigers, as well try to capture most of the remaining genetic variation and habitat diversity. Only such prioritization based on demographic, genetic, and ecological considerations can ensure species recovery and retention of evolutionary flexibility in the face of ongoing global changes. Although scientific understanding of ecological and demographic aspects of extant wild tiger populations has improved recently, little is known about their genetic composition and variability. We sampled 73 individual tigers from 28 reserves spread across a diversity of habitats in the Indian subcontinent to obtain 1,263 bp of mitochondrial DNA and 10 microsatellite loci. Our analyses reveals that Indian tigers retain more than half of the extant genetic diversity in the species. Coalescent simulations attribute this high genetic diversity to a historically large population size of about 58,200 tigers for peninsular India south of the Gangetic plains. Furthermore, our analyses indicate a precipitous, possibly human-induced population crash ∼200 years ago in India, which is in concordance with historical records. Our results suggest that only 1.7% (with an upper limit of 13% and a lower limit of 0.2%) of tiger numbers in historical times remain now. In the global conservation context our results suggest that, based on genetic, demographic, and ecological considerations, the Indian subcontinent holds the key to global survival and recovery of wild tigers.

Highlights

As top predators, large carnivores strongly shape ecological interactions in biological communities, playing a critical role in maintaining their structure and diversity [1,2]
Our data reveal that tigers of the Indian subcontinent retain most of the species’ genetic diversity, besides this region harbouring maximum diversity of tiger habitats
Genetic variation Our sampling strategy concentrated on tiger populations living in varied habitats throughout the Indian subcontinent

Summary

Introduction

Large carnivores strongly shape ecological interactions in biological communities, playing a critical role in maintaining their structure and diversity [1,2]. During historical times, increased anthropogenic impacts have driven range collapses and population declines in many large carnivores, thereby engendering significant efforts at species recovery. These efforts have typically aimed at increasing local population sizes and enhancing connectivity between populations using available demographic, ecological and genetic information for the species [3,4,5]. Wild tigers historically occurred across 70 degrees of latitude and 100 degrees of longitude, spanning 30 present-day nations ranging from Armenia to Indonesia, the Russian Far East to the Southern tip of India [6,7]. The genetic make up and diversity of Indian wild tiger populations have not been examined in a global context

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Conclusion