Reintroduction is a widespread tool for protecting endangered species and ecosystems. However, since founder populations are inevitably small, reintroduced populations have high potential for loss of genetic variation, in turn leading to a reduction in the population’s adaptive potential and thus enhancing the probability of extinction. The social behavior of a species can also have a major influence on the genetic diversity of a population, and fission-fusion structure for example, may have a high potential for preserving genetic diversity. The Asiatic Wild Ass, Equus hemionus, was reintroduced to the Negev Desert of Israel during the years 1982-93. In the first years following reintroduction Saltz and co-workers documented a social structure of territorial males, fission-fusion groups of females and separate bachelor groups. The current population in the Negev is estimated at more than 200 individuals. Yet, the social behavior and the genetic diversity of the population and their implications for the long term viability of the population are not known. We recorded and videotaped group composition from a shelter and built a unique individual identification profile for each individual. In order to evaluate the genetic potential of the wild population we amplified DNA from fresh feces and compared the allelic numbers of polymorphic microsatellites to those in DNA amplified from blood samples taken from the founder population. We recorded 377 observations: 251 of males, 105 of females with juveniles and only 21 of mixed groups (males with females), and created 78 individual profiles. We found that the same individuals appear on different days in groups of various sizes and compositions. The genetic results show that for all microsatellites the allelic number of the wild population remains almost similar to the original number in the founder population. We conclude that the current Wild Ass population exhibits a fission-fusion group's structure. This social structure may have contributed to the preservation of the allelic number, an indication of the preservation of genetic variability within the reintroduced population.
