Loss of Genetic Connectivity Due to Human Activity

A detailed study shows how human activity is impacting the genetic connectivity of four wide-ranging mammals of India.

The major reasons for the loss of biodiversity across the world are the changing landscape, habitat loss, global climate change, and fragmentation.
Now, human activity too can add to the list.
According to a study conducted by National Centre for Biological Sciences (NCBS), Bengaluru, human activity is leading to loss of genetic connectivity, which is the movement of animals across habitat patches for mating and genetic exchange.
The study was conducted in Central India among four wide-ranging mammals of India – tigers, sloth bears, jungle cats and leopards.
Genetic differentiation was studied among them.
To understand genetic connectivity, DNA extracted from faecal samples were studied.
The faecal samples were taken from nine protected areas between 2012 and 2017.

Juveniles of several mammalian carnivores leave their mother’s territory and move away to establish their own territory.
In this pursuit, males travel longer distances than females.
Isolation of habitat patches due to habitat loss and fragmentation are leading to restricted movement of these mammals across habitat patches and hence the exchange of genes through mating is being curtailed which increases the probability of extinction of a species.
Hence, maintaining connectivity is important for the long-term persistence of the species.

According to the study, the land-use pattern, population density, nearby roads and traffic affected the genetic structure of the species.
Of the species validated for the study, tigers found to be the most affected by the human footprint.
The study found that though tigers are known to travel long distances and often travel through agriculture fields, in Central India they do not have a high genetic exchange.
Jungle cats were found to be least impacted due to the variety of habitats they occupy that includes forests, scrublands, grasslands, and irrigated agricultural lands close to forests.
However, the research team for the study found several road-kills of jungle cats.
The team calls for building underpass and overpasses for mitigating road-kills and enabling smooth animal migration. Such structures will also ensure that habitat fragmentation is restricted.

The country is now paying attention to the issue of animal migration and as such works are being undertaken to build wildlife corridors.
Also, engineering reforms are also taking place so that infrastructure development does not hamper the movement of animals across habitats.
In 2019, a detailed document that lays out regulatory requirements for developing roads, railways, power lines had been released by the Ministry of Environment along with the Wildlife Institute of India.
The NHAI and all PWDs were instructed to follow these guidelines.