How humans affect genetic connectivity of four mammals

Four wide-ranging mammals — jungle cats, leopards, sloth bears and tigers — were studied in central India

Published - January 04, 2020 07:25 pm IST

Dangerous trend:  Isolation of habitat patches can restrict animal movement thus reducing genetic exchange and increasing extinction probability

Dangerous trend: Isolation of habitat patches can restrict animal movement thus reducing genetic exchange and increasing extinction probability

Changing landscapes, habitat loss, fragmentation, and global climate change have been listed as the main reasons for biodiversity decline worldwide. Now, a new study from the National Centre for Biological Sciences (NCBS), Bengaluru, has added to the growing knowledge that anthropogenic activities can impact genetic connectivity or the movement among habitat patches usually resulting in mating and genetic exchange.

“In several mammalian carnivores, juveniles disperse away from their mother's territory to establish their own territory. Males are known to travel longer distances than females. Isolation of habitat patches (due to habitat destruction and fragmentation) can restrict animal movement among habitat patches and thus reduce genetic exchange and increase the probability of extinction. Hence maintaining connectivity is critical to ensure long term persistence of a species,” Prachi Thatte explains. Dr. Thatte is the first author of the paper published in Diversity and Distributions and now works with WWF-India on connectivity conservation

Four wide-ranging mammals —Jungle cats, leopards, sloth bears, tigers —were investigated for the genetic differentiation in central India, which is a critical landscape for several species. The DNA extracted from faecal samples were used for understanding genetic connectivity. The samples were collected from nine protected areas during the period 2012-2017.

The team looked at how land-use, human population density, nearby roads and traffic affected the genetic structure. The paper notes that tigers were impacted the most by high human footprint. “Although known to travel long distances and move through agricultural fields to some extent, tigers in central India do not have equally high genetic exchange throughout the landscape. Some protected areas like Bandhavgarh tiger reserve seem to be getting relatively isolated (the 2014 tiger census report also shows the same),” explains Dr. Thatte.

Jungle cats were found to be the least impacted. “That is likely because in central India, they occupy a variety of habitats including forests, scrublands, grasslands and even irrigated agricultural fields close to the forests,” she explains.

Despite being the least impacted by human activity, the team encountered several jungle cat road-kills while carrying out fieldwork. She explains that with increasing infrastructure and traffic, systematically studying the impact of roads on smaller species like jungle cat and jackals and ensuring the presence of mitigation structures like underpasses and overpasses would be crucial to ensure that we don't fragment the currently well-connected populations.

IIndia has also started paying attention to wildlife corridors and encouraging engineering reforms to promote wildlife movements. Last year, the Ministry of Environment along with the Wildlife Institute of India released a document that lays out the regulatory requirements for developing roads, railways, powerlines while recognising the impacts on wildlife and people. NHAI and all PWDs have been instructed to follow the guidelines.

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