Monster Seminar JAM - Genetic Analysis of Reproductive Isolation in Sticklebacks
Dr. Katie L. Peichel, Human Biology, Fred Hutchinson Cancer Research Center.
What is the genetic basis of morphological and behavioral variation between species? How does this variation lead to the formation of new species? In order to address these questions experimentally, we are using the recently developed genetic linkage map of the threespine stickleback genome (Peichel et al. 2001) to identify genes controlling variable morphologies and behaviors related to reproduction and mate choice. Reproductive isolation between many threespine stickleback populations can result, at least in part, from differences in male morphologies and behavior and corresponding female preferences for these traits. One striking example is the evolution of black male nuptial coloration in several stickleback populations. We have initiated crosses from multiple populations with black nuptial coloration to identify the genetic and molecular basis of male nuptial color, and female perception and preference for male color. These studies will allow us to determine the number and identity of genes that control these traits, whether genes controlling male traits and female preferences are genetically linked, and if independently derived populations have used the same underlying genetic mechanisms to generate similar phenotypic divergence. One important reproductive trait that we have analyzed in detail is sex determination in threespine sticklebacks. We have genetically defined a single major locus that determines male sex and have found reduced recombination rates around this locus specifically in males. Although there is no evidence for heteromorphic sex chromosomes in threespine sticklebacks, our data suggests that males have an evolving Y chromosome. We have isolated male (Y) and female (X) specific BAC clones from the sex-determining locus. Comparison of over 300 kb of sequence from this locus has revealed a high rate of sequence divergence between the X and Y chromosomes, but very low rates of divergence between Y chromos
Date and Time:
December 11, 2003,
11:00 am - 12:30 pm