Takahito Shikano

Learn More
Examples of parallel evolution of phenotypic traits have been repeatedly demonstrated in threespine sticklebacks (Gasterosteus aculeatus) across their global distribution. Using these as a model, we performed a targeted genome scan--focusing on physiologically important genes potentially related to freshwater adaptation--to identify genetic signatures of(More)
Genome scan approaches to detect footprints of directional selection in the genomes of wild animal and plant populations have become popular tools to study local adaptation and speciation at the molecular level. Most studies thus far have used random molecular markers and found footprints of directional selection at, on average, 5% (range: 1-15%) of the(More)
Recombination suppression leads to the structural and functional differentiation of sex chromosomes and is thus a crucial step in the process of sex chromosome evolution. Despite extensive theoretical work, the exact processes and mechanisms of recombination suppression and differentiation are not well understood. In threespine sticklebacks (Gasterosteus(More)
Quantitative trait locus (QTL) mapping studies of Pacific three-spined sticklebacks (Gasterosteus aculeatus) have uncovered several genomic regions controlling variability in different morphological traits, but QTL studies of Atlantic sticklebacks are lacking. We mapped QTL for 40 morphological traits, including body size, body shape, and body armor, in a(More)
Studies of closely related species with different sex chromosome systems can provide insights into the processes of sex chromosome differentiation and evolution. To investigate the potential utility of molecular markers in studying sex chromosome differentiation at early stages of their divergence, we examined the levels and patterns of genetic(More)
Understanding the selective forces promoting adaptive population divergence is a central issue in evolutionary biology. The role of environmental salinity in driving adaptation and evolution in aquatic organisms is still poorly understood. We investigated the relative impacts of habitat type (cf. saltwater vs. freshwater) and geographic area in shaping(More)
Marker-based methods for estimating heritability have been proposed as an effective means to study quantitative traits in long-lived organisms and natural populations. However, practical examinations to evaluate the usefulness and robustness of a regression method are limited. Using several quantitative traits of Japanese flounder Paralichthys olivaceus,(More)
The genetic structure of contemporary populations can be shaped by both their history and current ecological conditions. We assessed the relative importance of postglacial colonization history and habitat type in the patterns and degree of genetic diversity and differentiation in northern European nine-spined sticklebacks (Pungitius pungitius), using(More)
Identification of genes and genomic regions under directional natural selection has become one of the major goals in evolutionary genetics, but relatively little work to this end has been done by applying hitchhiking mapping to wild populations. Hitchhiking mapping starts from a genome scan using a randomly spaced set of molecular markers followed by a(More)
Identification of genes involved in adaptation and speciation by targeting specific genes of interest has become a plausible strategy also for non-model organisms. We investigated the potential utility of available sequenced fish genomes to develop microsatellite (cf. simple sequence repeat, SSR) markers for functionally important genes in nine-spined(More)