Indian elephants lost genetic vigour as they moved north to south, 5 distinct populations exist: Study

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Sec: Species in news

Context:

A team of researchers from the National Centre for Biological Sciences (NCBS) and the Indian Institute of Science (IISc), Bengaluru, has discovered that Indian elephants migrated from the north to the south over millennia, gradually losing genetic diversity with each migration.
Their study analysed whole genome sequences from both wild and captive elephants across India, identifying five genetically distinct populations.

Key Findings:

Five Distinct Elephant Populations:
- One population along the Himalayan foothills (northwest to northeast)
- One in central India
- Three in southern India
Population Estimates (2017 Census):
- Total elephants in India: Over 29,000
- Southern populations: 14,500
- Central population: 3,000+
- Northern population: 12,000 (2,000 in the northwest, 10,000 in the northeast)

Genetic Divergence and Migration:

The northern population diverged from other populations more than 70,000 years ago.
Central Indian elephants diverged around 50,000 years ago.
The three southern populations diverged only about 20,000 years ago.

Genetic Diversity and Conservation:

The southern populations show reduced genetic variation, likely due to the “serial founder effect,” where smaller groups of individuals migrated southward, establishing new populations.
This reduced variation increases the risk of inbreeding depression (harmful genetic traits due to related individuals breeding).
The southernmost population (fewer than 150 elephants, south of the Shencottah Gap) has the lowest genetic diversity and is highly vulnerable to extinction.

Insights on Barriers to Elephant Movement:

The Palghat Gap and Shencottah Gap in the Western Ghats have acted as natural barriers, leading to three distinct southern elephant populations:
- North of Palghat
- Between Palghat and Shencottah
- South of Shencottah
The study also confirmed two previously identified populations:
- Central Indian elephants (from southwestern West Bengal to eastern Maharashtra)
- Northern elephants (in Uttarakhand, Uttar Pradesh, and the Northeast, separated by the Ganga and Brahmaputra rivers)

Importance of Habitat Connectivity:

The north Indian elephant landscape, from Uttarakhand to Arunachal Pradesh, once formed a single connected population. However, recent infrastructure development has disrupted gene flow, particularly in the Western Ghats.
The researchers emphasize the need for region-specific conservation strategies, given the genetic differences between populations.
The team plans to develop a genetic toolkit using DNA from elephant feces to monitor populations more accurately and identify individual elephants in the wild.

Source: IE