With over 9 million species estimated to exist on Earth, understanding the factors, both ecological and genetic, that contribute to species formation is a central problem in the biological sciences. While a half-century of research on the genetic basis of speciation has revealed some general insights, only a handful of genes contributing to speciation have been identified; thus, many questions remain. For example, what kinds of genes are involved in speciation? Are there few genes of major effect or many genes of small effect? These questions will be addressed by studying gene flow across a larger number of molecular markers in naturally occurring hybrid populations of two genetically well characterized house mouse species, Mus musculus and Mus domesticus, and through functional analyses of laboratory crosses between them. The goals of the research are to identify the number and characterize the biological function of genes contributing to speciation in house mice.
The research will involve the participation of postdoctoral researchers, graduate and undergraduate students and scientists in both the Czech Republic and Japan. House mice are important biomedical models and many of the speciation genes identified in this project are likely to shed light on genes important in reproduction and survival in humans.
The aim of this project was to identify regions of the mouse genome that are responsible for male sterility. This work was motivated by an interest in understanding how new species arise and by an interest in the genetic basis of fertility. Specifically, we studied two closely related lineages of house mice that hybridize in nature and can be crossed in the lab. When crossed, these lineages produce fertile daughters and sterile sons. The sterility of the male progeny is the basis for partial reproductive isolation. Thus, these mice provide an excellent model for understanding the genetic basis for the origin of new species. Mice were studied in their natural hybrid zone and also through laboratory crosses. Among the principal findings were the following: (1) the X chromosome plays a major role in reproductive isolation, (2) genes on the X chromosome interact with genes on other chromosomes to produce sterile males, (3) sterility is associated with over-expression of genes on the X chromosome during meiosis, and (4) several individual candidate genes have been identified. This work advances our understanding of the genetic details of reproductive isolation. It also has implications for understanding human male infertility, since the mouse is an excellent model for human traits and many of the genes identified in this work are also likely to be important in human male fertility. In addition, this work helped to provide training to graduate students and postdocs. Finally, this work also provided training to two visiting students from the Czech Republic, where there are fewer opportunities for scientific development.
