Animal Conservation

Genetic management of chondrodystrophy in California condors

Katherine  Ralls a1c1, Jonathan D.  Ballou a1, Bruce A.  Rideout a2 and Richard  Frankham a3
a1 National Zoological Park, Smithsonian Institution, Washington, DC 20008, USA
a2 Zoological Society of San Diego, Post Office Box 551, San Diego, California 922112, USA
a3 Department of Biological Sciences, Macquarie University, NSW 2109, Australia


Five out of 169 fertile California condor (Gymnogyps californianus) eggs laid in captivity have exhibited chondrodystrophy, a lethal form of dwarfism. Pedigree records indicate that this chondrodystrophy, like similar conditions in chickens, turkeys and quail, is probably inherited as an autosomal, recessive allele. We estimate that the frequency of this putative allele is about 9%. This high frequency is probably due to a founder effect. We consider three management options for the allele: ignoring it, eliminating it by selection and minimizing its phenotypic manifestation by avoiding matings between possible carriers. We recommend minimizing its phenotypic expression because an unacceptably large proportion of condors (up to 78 out of 146) would be prevented from breeding under a selection strategy designed to eliminate the allele. We predict that many captive populations will prove similar to the California condor population in that it will prove inadvisable or impractical to select against one or more deleterious alleles detected in the population.

(Received June 14 1999)
(Accepted November 12 1999)

c1 National Zoological Park, Smithsonian Institution, Washington, DC 20008, USA