Genetic Basis for Invasive Colonization in Sticklebacks

One of the big unsolved problems in conservation biology is how invasive species can adapt to a variety of environments, despite the fact that they often suffer from low genetic variations. Expanding genomic technologies may help us to answer this question. First, whole genome re-sequencing will help us to better estimate genetic variations of ancestral and exotic populations. Such information will also help us to identify genomic regions under the target of natural selection during colonization. Second, genomic techniques, such as QTL mapping and transcriptome analysis, will help us to understand the molecular mechanisms underlying adaptive evolution and phenotypic plasticity. We are investigating the genetic basis for rapid phenotypic shifts in threespine sticklebacks (Gasterosteus aculeatus) that were exposed to human perturbations, struck by a big tsunami, or introduced into depauperate carter lakes. Our results demonstrate that standing genetic variations substantially facilitate rapid adaptive evolution in some cases. Furthermore, whole genome re-sequencing revealed more heterozygosities than expected by classical genetic analyses in exotic stickleback populations. Thus, further researches on the genetic basis for phenotypic shifts and invasiveness will be possible in the sticklebacks, which may help to understand how invasive fishes can adapt to a variety of novel habitats.