How much gene flow is needed to avoid inbreeding depression in wild tiger populations?

Area of Science:

• Conservation Biology
• Population Genetics
• Wildlife Ecology

Background:

• Tiger populations are declining and fragmented due to habitat loss, fragmentation, and poaching.
• Current tiger populations are small, isolated, and have experienced inbreeding for approximately seven generations.

Purpose of the Study:

• To investigate the impact of inbreeding on the persistence of tiger populations.
• To assess the effectiveness of natural or artificial dispersal in mitigating inbreeding depression.

Main Methods:

• Development of a tiger population simulation model.
• Incorporation of published genetic load data for mammals to simulate inbreeding depression.
• Introduction of 1-4 dispersing male tigers per generation after 50 years of isolation to model gene flow.

Main Results:

• For small populations, even four dispersing males per generation did not improve viability, with over 90% extinction risk within 30 years.
• Medium-sized populations are likely to go extinct within 70 years without intervention.
• Only a few of the largest tiger populations may survive without habitat restoration and gene flow.

Conclusions:

• Habitat connectivity is essential for reducing local extinction risks and must be prioritized alongside increasing population size.
• Conservation efforts should focus on enhancing habitat quality and availability.
• Infrastructure development must be carefully planned to avoid further habitat degradation for tiger populations.