Genetic variability among chimpanzee subspecies and the implications for
biomedical research.
Dr. John J. Ely, Bioqual, Inc., Rockville, MD, 20850, USA
Chimpanzees (Pan troglodytes) are our most closely
related non human primate relatives genetically and resemble us in many phenotypic and
cultural traits. Consequently, chimpanzees are of considerable interest to anthropologists
interested in human evolution and are a vital animal model in biomedical research. In the
last 5-10 years, extensive progress has been made using DNA techniques for characterizing
the chimpanzee genome and to elucidate the genetic structure of natural chimpanzee
societies. Laboratory work has proceeded through the characterization of non-coding but
highly polymorphic short tandem repeat (STR) markers, creating multilocus DNA profiles for
characterizing individuals and populations. Fieldwork has proceeded through sequencing the
non coding but hyper variable mtDNA D-loop, primarily in West and East African
populations, then analyzing the data to detect population structure. These areas of
inquiry have proceeded in relative isolation. However, since legal export of African
chimpanzees terminated with CITES 25 years ago, most African-born founders of captive
breeding populations have died or become aged, many of whom failed to reproduce in
captivity. Although strong, direct evidence of nuclear genetic differences among
chimpanzee subspecies is not yet forthcoming, some phenotypic differences with probable
genetic bases are known. Meanwhile, a powerful bias in subspecies composition of captive
NIH-supported populations has been revealed, even as the origins of several newly emerged
viral pathogens, including HIV-1 and simian foamy viruses, have been traced to the Central
African P.t. troglodytes subspecies. Today, founder contribution to captive
populations has become a critical issue, human genome advances are increasingly impacting
non human primate genetics, and captive and naturalistic studies are converging. In my
survey, I will report on subspecies composition of NIH captive breeders, on the use of
STRs to define genetic uniqueness among founders, on how nuclear and phenotypic genetic
differentiation among chimpanzee subspecies might impact biomedical research (especially
hepatitis and AIDS, the primary human diseases for which chimpanzees are used as models),
and on the directions chimpanzee genetics research should take in the immediate future.