Meeting Abstract
Adaptation requires genetic variation upon which natural selection can act. There are three major sources of genetic variation: (1) new mutations, (2) standing genetic variation, and (3) introgressed variants from other species. Introgressed variants are especially intriguing because they may arise faster than new mutations, can include multiple mutations on a single haplotype, and have been tested by selection in the species of origin. Mus musculus and M. spretus diverged an estimated 1.5-3 Mya, have a genetic divergence of about 1%, and are broadly sympatric. The two species have many morphological and life history differences. Additionally, there is a significant fitness disadvantage to hybrids; F1 males are completely sterile and genomic incompatibilities exist between the two species. Several previous studies have revealed introgression of alleles from M. spretus into M. musculus. Here we find evidence for directional introgression from M. m. domesticus into M. spretus populations at over 100 genomic regions, with high variability of introgression patterns between individuals. Additionally, we used selection tests to categorize these introgressed regions as neutral or putatively adaptive.
