There have been too many people and not enough California condors in Topatopa’s life. Although instinct has programmed this 22-year-old survivor of a dying species to express an interest in breeding, he just can’t muster the nerve to respond to his domineering mate’s sexual advances. So they have yet to produce a chick.
“Being raised for 20 years without even another bird, let alone a condor, he has some things to get over,” explained Mike Wallace, curator of birds at the Los Angeles Zoo, where Topatopa lives.
But the results of a new genetic analysis technique being used on the last surviving condors have given new impetus to a plan to get Topatopa an avian annulment and switch him to another, more submissive, mate.
“The important thing is to get his genes into the population as soon as possible,” Wallace said.
That is because Topatopa represents a hereditary lineage unique among the 28 condors in zoos in Los Angeles and San Diego, according to the preliminary results of genetic “fingerprinting” done by scientists at the San Diego Zoo and Wild Animal Park.
The tests indicate that if Topatopa were to die before producing any offspring, an entire set of hereditary information crucial to the species’ future would be lost. For a small population, this would represent a serious loss, because the more genetic diversity a population has, the more viable it is over the long term.
These findings and other preliminary results of the analysis conducted over the last year are provoking cautious excitement among officials of the California condor recovery program, a federal-state effort to rescue the birds from extinction.
Although the results in some cases haven’t been surprising, they nevertheless appear to show that genetic fingerprinting will be a viable and important tool for assuring the best possible pairings of birds for breeding, said Joseph J. Dowhan, chief of the condor recovery effort for the U.S. Fish and Wildlife Service.
Genetic fingerprinting was developed in 1985, as the result of the discovery that strands of DNA--the chemical blueprint for all organisms--contain many short sections that are distinctive to each person, except identical twins.
It involves extracting the DNA from a blood or tissue sample and using an enzyme to chop it up into small fragments. When the fragments are separated, using a technique called electrophoresis, they form a unique pattern of bands that can be compared between individuals.
In the condor studies, geneticist Oliver Ryder of the San Diego Zoo is among a handful of researchers worldwide testing the validity of genetic fingerprinting in animals. Using small blood samples taken from the condors during normal health checks, he so far has used two enzymes to develop two different sets of genetic fingerprints for the condors.
Condors known to be siblings shared 70% to 90% of the same genetic fingerprint bands, he said. Because the correlations were consistent in both enzyme tests, the technique appears to be valid for condors, he said.
“The values are different for different enzymes, but the phenomenon was the same. Those birds that jumped out as being closely related with one enzyme were also closely related with the other enzyme,” Ryder said.
Pairing the Birds
After hearing Ryder’s results last month, the condor recovery team decided to move quickly to give Topatopa a new mate so his genes can be preserved. He will be paired with Anyapa, a 4 1/2-year-old condor at the Los Angeles Zoo.
The team also chose six other new breeding pairs, said Lloyd Kiff, who chairs the panel advising federal officials in charge of the program.
“In at least a couple of cases, Ollie’s results had considerable bearing on which birds we put together,” Kiff said. “If we had a male that we could put together with any of three females, we just went with the ones that seemed to be the farthest away (genetically).”
But, with such a small population, considerations such as compatibility also had to be taken into account, Kiff noted.
Genetic fingerprints indicated that Cuyama and Cachuma, both at the Los Angeles Zoo, are close relatives--although they don’t appear to be siblings--but they will be paired anyway, Kiff said.
“The birds are a little more closely related than we’d like, but they’re getting along so well that we’re just going to leave them together and see if they breed,” Wallace said.
Ryder’s tests also indicated that AC-4, the father of the captive-bred chick hatched in San Diego last spring, seems to have a genetic makeup “almost identical” to that of another male condor, AC-6. This indicates that they are products of inbreeding already.
“Their parents might have been siblings and their grandparents might have been cousins or something like that,” Wallace said.
This finding tempers biologists’ disappointment at AC-6’s failure so far to breed, “since his genes are already preserved” in AC-4’s chick, said Cathleen Cox, research director at the Los Angeles Zoo.
Fortuitously, the tests also showed that AC-4 and UN-1, parents of the captive-bred Molloko, do not appear to be closely related. Because both parents were hatched in the wild of unknown parentage, zoo officials previously had no way of knowing whether they were genetically compatible.
Inbreeding is a problem because it can result in ineffective breeding, infertile eggs and weak or deformed offspring.
Ryder is cautious about conclusions based on his results so far, though. He objects, for instance, to labeling Cuyama and Cachuma as “cousins.” The genetic fingerprints have been developed on the condors only using two DNA-cutting enzymes of more than two dozen possible, and further studies with some of those other enzymes are needed, he said.
But Ryder clearly hopes that at some point in the future he will have enough data to make complex inferences about the birds.
“The goal is to try to see whether the fingerprinting approach could be usefully applied to trying to make degrees of inferences about relatedness that we don’t know,” Ryder said. “That’s really a new application of the fingerprinting technology.”
The California condor data will also be checked by using studies of a surrogate and easily studied species, the Andean condor, he said.
Up until now, genetic fingerprinting in humans has been used as an identification tool--to establish paternity or to establish the presence of a criminal suspect at a crime scene based on minute amounts of blood or semen there.
With results from pioneering studies such as Ryder’s, wildlife biologists hope eventually to use the technique to help them ensure genetic diversity among captive populations of endangered species.
The California condor once ranged all along the West Coast, from British Columbia to Baja California. The birds numbered just 100 by the turn of the century and had declined to about 40, all in California, by 1976.