Ancient DNA from Andean Bears Shows Genetic Decline

One of GROW Colombia’s research projects is conducted by Dr Camilo Chacón-Duque as part of GROW’s collaboration with the Natural History Museum. The project aims to investigate the historic genetic diversity of Colombia’s Andean bear populations by sequencing DNA taken from bears who lived in Colombia in the last few centuries and who are now part of museum collections. This information will enable GROW to compare previous bear genetic diversity to those bears living in Colombia now.

We used DNA from 15 museum specimens collected throughout Colombia from 1913 to 2008. According to our analyses, there is a clear negative correlation between the date of the specimen collection and the amount of genetic diversity contained within its genome. That means that, in almost a century the bear’s genetic diversity has declined sharply.

What caused this genetic decline?

Researchers and conservationists think this decline has been caused mainly by the reduction and fragmentation of the bears’ habitat. Over the last 100 years, as urban development has spread and the climate has changed, the areas where the bears used to live have become much smaller, populations of bears have become separated from each other by roads and industrial activity.

What does this mean for the existing populations of Colombian Andean bears?

With fewer bears, living in small and fragmented areas, the genetic pool – also known as the genetic variability – is reduced. The more drastic this reduction is, the higher the chances of the bears accumulating harmful genetic variation. Populations of bears that are genetically very similar, will be less resistant to diseases and other threats to their survival. Sadly, without effective conservation initiatives (like conservation corridors to reconnect wild bear populations) we expect to see even more decline in the number of bears living in Colombia over the coming years, and in the not-too-distant future they could become endangered.

GROW is now assessing the Andean bear genome piece by piece to establish whether specific regions of the genome have been affected in different ways by this decline. This information will enable us to estimate which bears will be more genetically susceptibility to threats such as climate change or disease. We will use this research to inform conservation strategies to protect bears for generations to come.