GENETIC-BASIS FOR MALE-AGGRESSION AND SURVIVORSHIP IN WILD HOUSE MICE(MUS-DOMESTICUS)

Work on the genetic region of the house mice known as the t-complex ha s produced the hypothesis that mice heterozygous for t-haplotypes (+/t ) may have a selective advantage over wild-type (+/+) males owing to t he greater aggressiveness of +/t males. We tested this hypothesis by e xamining the behavior of +/+ and +/t mice placed in four large outdoor enclosures. We found that +/t males were dominant over +/+ males. Fur thermore, in the outdoor enclosures +/t males had higher survivorship than +/+ males, both as adults and juveniles. However, males of the tw o genotypes did not differ in home range size. We suggest that t-haplo types may be, in part, maintained in mouse populations because of a se lective advantage in heterozygous males. (C) 1996 Wiley-Liss, Inc.