Frequency and distribution of t-haplotypes in the Southeast Asian house mouse (Mus musculus castaneus) in Taiwan

t-haplotypes are a meiotic drive system found on the 17th chromosome of the house mouse Wits musculus). They can be found in wild populations of all f our genetically differentiated subspecies. The drive phenomenon is mate-spe cific, such that heterozygous mates (+/t) show non-Mendelian transmission a nd transmit the t-chromosome to > 90% of their offspring. So far the most c omprehensive studies on the frequencies of t-haplotypes in natural populati ons have been on just one of the subspecies (M. musculus domesticus). We ap plied molecular methods to accurately screen t-haplotypes in a large number of populations of a second subspecies (M. musculus castaneus) distributed in Taiwan. We found that the overall t-haplotype frequency is low in M. m. castaneus (0.108), and the chromosomes are patchily distributed among its p opulations, closely resembling the situation found in M. m. domesticus. Fur ther, we found the frequencies of t-haplotypes in our sample did not differ in relation to the sex or age of mice. This resemblance in the frequency a nd distribution among populations of the two distinct subspecies suggests t hat similar general mechanisms might be responsible for the low frequencies in both subspecies.