What numbers do not reveal about tiger conservation?
GS Paper 3: Conservation, Environmental Pollution and Degradation, Environmental Impact Assessment.
Mains exam: Tigers conservation.
Extinction, this ominous word has one meaning. The death of a species. And it is a word that we seem to hear so often these days, especially in the news. But the opposite is possible. July 29, which is Global Tiger Day (also called International Tiger Day), the world and India can celebrate the recovery of at least one endangered species.
Increase in number in India: Cause for celebration
India is now reporting increased tiger numbers, and a recent International Union for Conservation of Nature assessment suggests that tiger numbers have increased by 40% since 2005. This is cause for celebration. But is the rise in tiger numbers enough to prevent their extinction?
Reasons behind high probability of extinction
• Populations that are smaller than 100 breeding individuals have a high probability of extinction.
• At the same time, for populations to persist, they should be part of larger landscapes with other such populations that are connected.
• This is because small populations are subject to chance/random events.
o These random events may cause them to lose advantageous genetic variants, while other, detrimental genetic variants might increase in frequency.
Genetic drift describes random fluctuations in the numbers of gene variants in a population.
• Individuals in small populations are more likely to be related, leading to inbreeding.
• This exposes the many slightly disadvantageous genetic variants that are present in all genomes.
• When expressed together, these detrimental genetic variants cause inbreeding depression, and reduced survival and reproduction of inbred individuals.
• Results showed that extinction could be avoided if corridors were safeguarded.
• As long as we manage landscapes outside tiger reserves to allow tiger movement, and protect prey and tigers inside tiger reserves, tigers are sure to survive in landscapes such as central India.
Genetic effects of isolation and small population sizeM
• Pseudo-melanistic or black tigers found in Odisha has demonstrated the genetic effects of isolation.
• Black tigers were found only in the Similipal tiger reserve in Odisha.
• Genome sequences of a litter of zoo tigers that included pseudo-melanistic cubs revealed that a single spelling mistake (or mutation) in a specific gene causes these tigers to look this way (black).