What numbers do not reveal about tiger conservation

Source: This post is based on the article “What numbers do not reveal about tiger conservation” published in The Hindu on 29th July 2022.

Syllabus: GS 3 – Environment and Bio-diversity: Conservation.

Relevance: Tiger conservation.

News: On International Tiger Day, the world and India can celebrate the recovery of at least one endangered species. A recent International Union for Conservation of Nature assessment suggests that tiger numbers have increased by 40% since 2005.

What is the relation between population and 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. Small and isolated populations face a high probability of extinction.

This is because there is a high chance of inbreeding that will expose disadvantageous genetic variants that are present in all genomes.

Does increasing tiger count prevent them from extinction?

Most tiger ‘populations’ are smaller than 100. On their own, most tiger populations do not have a high chance of survival. This is because,

a) Most tiger reserves in India are small and embedded in human-dominated landscapes, b) The presence of built-up areas and high-traffic roads greatly impeded tiger movement, and c) Fencing tiger reserves and isolating them could result in high extinction.

However, most land-use types were not too bad for tiger connectivity, including agricultural fields. Tiger extinction could be avoided if tiger corridors were safeguarded. For instance, having an underpass will allow wildlife movement and connectivity.

What are the findings on tiger conservation in Odisha and Rajasthan?

Similipal tiger reserve: The black tigers were found only in the Similipal tiger reserve in Odisha. These pseudo-melanistic or black tigers demonstrated the genetic effects of isolation. A single spelling mistake (or mutation) in a specific gene (genetic drift) causes these tigers to look this way.

It was common only in Similipal, where 60% of the tigers carried at least one copy of a causal genetic variant.

Ranthambore tiger reserve: Genome sequences from wild tigers reveal that individuals in the Ranthambore tiger reserve show inbreeding. However, there is no adverse effects of inbreeding yet. But it might happen in near future.

What should be done to ensure tiger conservation?

1) Special attention is needed for populations that are becoming isolated and facing the genetic consequences of such isolation, 2) The countries should carry a genetic rescue plan or even the introduction of novel genetic variants using the genome sequencing technology, 3) The future of tigers will require a ‘dialogue’ between data and management strategies in order to ensure their survival.