Climate change and evolution of Cross River gorillas

April 1, 2011

Two species of gorillas live in central equatorial Africa. Divergence between the Western gorillas (Gorilla gorilla) and Eastern Gorillas (G. beringei) began between 0.9 and 1.6 million years ago and now the two species live several hundred kilometres apart. New research published by BioMed Central's open access journal BMC Evolutionary Biology shows that the divergence of Western lowland gorillas and the Critically Endangered Cross River gorillas (G. g. diehli) occurred more recently, about 17,800 years ago, during the Pleistocene era.

An evolutionary model of the two subspecies of Western gorillas was generated using microsatellite genotyping of living gorillas and 100 year old museum specimens. This data showed that, although Cross River gorillas diverged from Western lowland gorillas about 17,800 years ago, the two subspecies continued to intermittently interbreed. Drs Thalmann and Wegmann suggest that climate change during the Pleistocene era caused the forests to expand, permitting the Western gorillas to expand their range. When the forest contracted again the gorillas were separated into two populations which began to diverge. Successive rounds of resulted in periods when the two subspecies could interbreed followed by repeated episodes of isolation of the Cross River population.

The model indicates that finally stopped between the two approximately 420 years ago. Over the last 320 years ago there has been a 60% decrease in the numbers of Cross River gorillas causing a loss of genetic diversity within the population. Dr Thalmann said, "The number of Cross River gorillas has continued to decrease, probably due to anthropogenic pressure, such as destruction of their habitat or hunting by humans. There are thought to be fewer than 300 individuals left."

He continued "It is unclear what effect this loss of will have on the long term viability of Cross River gorillas. But, given that this bottleneck occurred so recently, it is possible that if the population was allowed to expand the loss of diversity could be stopped."

Explore further: Uganda's gorilla population growing

More information: Historical sampling reveals dramatic demographic changes in western gorilla populations, Olaf Thalmann, Daniel Wegmann, Marie Spitzner, Mimi Arandjelovic, Katerina Guschanski, Christoph Leuenberger, Richard A Bergl and Linda Vigilant, BMC Evolutionary Biology (in press).

Related Stories

World's most endangered gorilla fights back

December 5, 2007

In the wake of a study that documented for the first time the use of weaponry by Cross River gorillas to ward off threats by humans, the Wildlife Conservation Society announced today new field surveys to better protect this ...

Study garners unique mating photos of wild gorillas

February 12, 2008

Scientists from the Wildlife Conservation Society and Max Planck Institute for Evolutionary Anthropology have released the first known photographs of gorillas performing face-to-face copulation in the wild. This is the first ...

New national park protects world's rarest gorilla

November 26, 2008

The Wildlife Conservation Society, the Government of Cameroon, and other partners have collaborated to create a new national park to help protect the world's most endangered great ape: the Cross River gorilla.

World's rarest gorilla ready for its close-up (w/ Video)

December 16, 2009

The world's rarest -- and most camera shy -- great ape has finally been captured on professional video on a forested mountain in Cameroon, according to the Wildlife Conservation Society and Germany's NDR Naturfilm.

Recommended for you

Researchers discover new type of mycovirus

July 29, 2015

Researchers, led by Dr Robert Coutts, Leverhulme Research Fellow from the School of Life and Medical Sciences at the University of Hertfordshire, and Dr Ioly Kotta-Loizou, Research Associate at Imperial College, have discovered ...

Stressed out plants send animal-like signals

July 29, 2015

University of Adelaide research has shown for the first time that, despite not having a nervous system, plants use signals normally associated with animals when they encounter stress.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.