Trappability of Wild House Mice (Mus domesticus) in Large Outdoor Pens: Implication for Models of t-complex Gene Frequency

Abstract

-Wild house mice (Mus domesticus) are commonly heterozygous (+/t) for a genetic mutation referred to as a t-haplotype, in the t-complex of chromosome 17. Considerable debate has been concerned with the factors controlling the frequency of heterozygotes in wild populations. However, differential trappability of heterozygous and wildtype (+/+) mice could seriously affect this estimate. We examined the relative propensity of +/t and +/+ mice to enter Sherman live traps placed in large outdoor pens. Overall, males are more likely to enter traps than are females. Additionally, more aggressive males are more likely to enter traps than are less aggressive ones. However, there was no statistically significant effect of male t-complex genotype on capture rate. In contrast, +/t females were significantly less likely to enter live traps than their +/+ counterparts. Trapping bias favoring +/+ over +/t females could result in a small (ca. 10%) underestimate of the frequency of t-haplotypes among wild mice.