Genome Studies of Great Apes in the Wild and in Zoos
Samples from our Frozen Zoo® have contributed to a study of historic importance in primate biology: a cornerstone has been laid in the application of genome sequencing technology to understanding the biology of our closest relatives, the great apes, that includes the chimpanzee, bonobo, gorilla, and orangutan.
In July, the journal Nature, published a report of the sequencing of 79 great ape genomes, providing evidence for distinct populations within species. It signals the flow of genes between these populations and evidence for inbreeding within populations.
Studies of DNA sequence variation in great ape genomes has been limited in terms of the numbers of animals studied and the amount of DNA sequence information amassed. This new study is the most comprehensive study yet undertaken, increasing six-fold the number of genomes previously analyzed. The gathering of samples, generation of data and analysis for this genome-wide comparison among the great apes involved an international team of 75 investigators, consistent with the diversity of expertise and extent of effort required to undertake studies such as these.
The first genetic study of mountain gorillas was undertaken by the San Diego Zoo Institute for Conservation Research in the 1980s. Over the intervening years, we have amassed a collection of gorilla cell cultures and DNA extracts, in collaboration with other zoos and with field biologists. Knowledge of the presence of distinct populations of western lowland gorillas was advanced in an extensive study performed by Anthony Nsubuga, a postdoctoral fellow from Uganda.
Dr. Bethan Morgan, Head of the Central Africa Regional Program for the Institute, was the first scientist to observe the gorillas of the Ebo Forest in Cameroon. Since that time, she has championed efforts to gather knowledge about this isolated population and protect these apes and their habitat.
Samples of Ebo Forest gorilla dung are being analyzed by Asako Yamamoto in the laboratories of the Genetics Division to shed light on the relationship of the Ebo Forest gorillas to other distinct populations of gorillas, as well as to assess their genetic vulnerability through inbreeding.
Data obtained from the just-published study of great ape genome variation will aid these studies through identification of Ancestry Informative Markers (AIMs) that may be scrutinized in even poor quality DNA samples, such as are obtained in dung.
DNA sequence variants that are unique to separate gorilla populations, that constitute AIMs, may be assessed through newly generated technologies. Utilization of technologies developed for understanding the evolution of the human genome has in the past and will continue to contribute to efforts to gather information with conservation impacts.
In this way, efforts to contribute understanding human biology and medicine have fostered collaborations and provided resources for projects such as the great ape genome sequencing efforts, in which the Institute partners with Dr. Evan Eichler’s laboratory in the Department of Genome Sciences at the University of Washington.
Many aspects of the distribution and genetic make-up of great apes for which a dim understanding has impeded conservation actions are in a better position to be addressed as the light of genome biology illuminates our understanding.
The large community of scientists that contributed to the recent Nature paper hold hope that the knowledge they generate can contribute to taking steps necessary to protect sustainable populations of great apes and assure their survival, while fully knowledgeable of the range of issues threatening the existence of great apes, including loss of habitat, poaching, and disease must be addressed.
Oliver Ryder, Ph.D., Genetics Division, San Diego Zoo Institute for Conservation Research.