Molecular mechanisms of speciation and macroevolution

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We investigated the genetic mechanism of speciation by focusing on the Lake Victoria cichlid species and that of the evolution of mammalian morphological characteristics. We found, 1) the unique sex determination system caused by the B chromosome, 2) highly dimorphic allelic diversity of pheromone receptor genes, and 3) the clear correlation between nuptial colors and visual sensitivities tuned by opsins. In addition, by constructing a genetic linkage map, we identified the putative sex determination region in the autosome of the Lake Victoria cichlids. For mammalian evolution, we identified several AmnSINE1-derived distal enhancers for developmental genes expressed in mammalian diencephalon and callosal projection neurons. We revealed the detailed molecular function and evolutionary process of the enhancers. Our findings concerning the molecular mechanisms of speciation and large-scale morphological evolution are expected to be applicable in broad animals in general.