The Mexican Gray Wolf subspecies, Canis lupus baileyi , was listed as endangered in 1976. Mexican wolves were thought to be extirpated from the U.S. and greatly reduced in Mexico by 1970. There has been no confirmed evidence of wild Mexican Wolves in Mexico in the last decade, so they are now considered extinct in their ancestral range. As a result, wolves captured in Mexico from 1972-1980, were taken to the U.S. to start a captive breeding program. These wolves are the founders of the Certified lineage. There were six wolves caught that year in Durango and Chihuahua (Mexico), five males and one pregnant female, but some of these wolves were offsprings of the others. This lowered the number of founders to 3 (one female and two males) or, by taking the sex ratio effect into account when calculating the effective population size, the number of founders is 2.67.
Photo © Neil B. Carmony [Brown,1983]
Wolf Portrait taken at the Arizon-Sonora Desert Museum.
This wolf is one of the male litter-mates from the female trapped
in Mexico and one of the founders of the current captive population.
These founders started a lineage that was proposed to be reintroduced to the Southwestern United States. Because of the small number of founders, some scientists (Hedrick et al, 1997) have shown that this population has very little genetic variabilty. They worried that these wolves had a low heterozygosity, and might suffer from inbreeding depression or a genetic disease. These same scientists did a study of two other, captive bred Mexican wolves lineages , and proposed breeding them with the Certified Lineage at a ratio of 80% (Certified) to 20% (the other two lineges, combined). This propsal was accepted by the Mexican Wolf Species Survival Group in July of 1995, and it is this, combined lineage that is proposed to be reintroduced to the Southwestern United States.
In addition to the captive breeding and reintroduction programs, there is also a program to freeze the sperm of Mexican wolves. This frozen sperm is thought to be an opportunity for scientists in the future to be able to conserve to genetic diversity of the species. As of right now, the sperm of nine wolves is being maintained at the St. Louis Zoo, and five more wolves' semen will be collected during the 1997 breeding season.
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