Spatial variation in the response of tiger gene flow to landscape features and limiting factors

Integrated landscape management of key population areas along with the corridors linking them is important for tiger conservation in the Indian subcontinent. Relationships between gene flow and landscape patterns, however, cannot be generalized given that different limiting factors influence movement in different spatial contexts. Here, we study the landscape features affecting tiger gene flow in the Western Ghats, and examine how and why limiting landscape features differ between Central India and the Western Ghats. We also assess whether these landscape features have been altered by land use changes in the last five decades. Our study area covers 30 000 km(2) from Bhadra Tiger Reserve to the Nilgiri Biosphere Reserve in India. We used genetic data of 115 tigers and landscape resistance model optimization to create a resistance surface to gene flow in the Western Ghats. Tiger gene flow, both in Central India and the Western Ghats, is primarily related to topographic roughness and secondarily to diffuse disturbance, however these relations are inverted in the two landscapes - in Central India, gene flow correlates with rough terrain, whereas in the Western Ghats, it correlates with smooth, forested terrain with minimal human disturbance. Topographic complexity is an important factor affecting tiger dispersal, but tiger's response to topography seems to be dependent upon interactions with human-related disturbance. Tigers in Central India favor rough terrain for dispersal primarily because it is the only part of the landscape without heavy human footprint and the last refuge for natural vegetation, whereas in the Western Ghats, forest cover is more extensive in flatter terrain and human footprint is generally lower.