THE GENETIC HISTORY OF AN ISOLATED POPULATION OF THE ENDANGERED GREY WOLF CANIS-LUPUS - A STUDY OF NUCLEAR AND MITOCHONDRIAL POLYMORPHISMS

The grey wolf was thought to have been exterminated in the Scandinavia n peninsula when the sudden appearance of a few animals in southern Sw eden was reported in 1980. These wolves founded a new Swedish populati on which currently numbers at least 25 individuals, one of the world's smallest populations of the species. The sudden occurrence of the fou nder animals caused speculation that these had not appeared by 'natura l' means but rather were Swedish zoo animals deliberately released by man. To analyse if this was the case and to elucidate the genetic stat us bi; this small and isolated population, we assessed nuclear and mit ochondrial (mt) genetic variability in wild and captive grey wolves, u sing microsatellite typing and sequence analysis of the mtDNA D-loop. The new population was found to be monomorphic for a mtDNA haplotype w hich also was present in the Swedish zoo population. A total of four d ifferent mtDNA haplotypes were found among all captive and wild wolves (including two animals from an occasional establishment of a few wolv es in northern Sweden in the late 1970s), with a maximum sequence dive rgence of 3.1 %. Despite the mtDNA congruence, animals from the zoo po pulation could most likely be excluded as founders for the wild popula tion since the latter group of animals displayed several unique micros atellite alleles (i.e. alleles not found in the zoo population). Moreo ver, a phylogenetic analysis of individual wolves, using microsatellit e allele sharing as distance measure, placed all wild animals on a bra nch separated from that of the captive animals. The average degree of nuclear variability as well as allelic diversity was similar in the wi ld and the captive populations, respectively, but was lower than that reported for North-American populations of grey wolves. Polymorphism h as declined in wild wolves born in recent years suggesting that this s mall population is currently suffering from a loss of genetic variabil ity due to inbreeding. Inbreeding depression is documented in captive wolves and the long-term survival of the wild Swedish population may t herefore depend on immigration of animals from Russia. This study illu strates the usefulness of microsatellites for dissecting close genetic relationships and for addressing the genetic status of individuals.