- Population expansion and gene flow are the two factors which will greatly influence the future of the 3600 remaining tigers living in fragmented habitats.
- Gene flow, which is the ability of the species to migrate and interbreed outside their territorial gene pool, results in greater genetic diversity and eventually increasing the fitness of a given species. This is vital in protecting this endangered species.
- In cases of low gene flow, tiger populations would have to compensate with an unattainable growth rate to maintain current levels of genetic diversity. Lower genetic diversity requires greater population number to ensure survival of species.
- According to a simulation conducted, if fragmentation led to the complete isolation of the estimated 402 tigers in the Western Ghats, the population would have to rise to 18,000 individuals to maintain the same genetic diversity in 150 years.
- This was conducted using previously sequenced DNA of 125 individuals (from five existing tiger subspecies: Sumatran, Malayan, Bengal, Indochinese and Siberian) to predict the population size needed to maintain existing genetic diversity 150 years from now.
- Protecting genetic diversity is vital in mitigating the detrimental effects of in breeding, as reduced genetic diversity may affect the population in many ways including reduced reproductive capacity, increased cardiac defects and prevalence of infectious diseases.
- In Florida panther, a puma subspecies, the number reduced to 30 individuals after a dramatic decrease in its range in the 1990s. The demographic reduction resulted in inbreeding thereby shrinking the genetic diversity of the subspecies.
- In breeding may occur as a result of fragmented habitats. Promoting gene flow however is harder than attempting to increase population as focus should be beyond park boundaries and on the natural dispersal of these animals.
- According to a study, an individual tiger had migrated over a distance of up to 600 km in its lifetime in Central India, putting in danger everything from highways to human habitation thereby highlighting the need for landscape-level connectivity as most wild tigers live in small, isolated protected areas within human dominated landscapes in the Indian subcontinent.
- Although inbreeding has not yet affected wild tigers, increase in poaching has eliminated an average of 104 tigers every year since 2000 resulting in the extinction of 3 of the 9 subspecies – Bali, Javan and Caspian.
- Indian subcontinent which houses 60% of the world’s total tiger population exhibits significant genetic diversity. The reserve of genetic diversity once lost will take millions of years to regain even with increase in population numbers.
- Every tiger, in wild or in zoos, is important as a potential reserve of the genetic diversity of the species.
- Read at: http://www.thehindu.com/todays-paper/tp-features/tp-sci-tech-and-agri/the-future-of-the-tiger-hinges-on-gene-flow/article5964677.ece
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