This research is concerned with the genetic architecture of the MSP (major sperm protein) gene family in Caenorhabditis elegans and related nematodes. Gene families appear to be adaptive solutions to the demand that cells produce certain kinds of proteins in great abundance, and the MSP gene complex is a paradigm for this evolutionary mode. MSP in C. elegans is coded by 40-50 genes that occur in four clusters on two chromosomes. Genes within clusters are more similar in sequence than are genes residing in different clusters. Hypothetical mechanisms for the evolution of gene families include the "radiation" of duplicate genes within a cluster from an ancestral gene (in which case similarity is by descent) and gene conversion in which sequence information is homogenized within a cluster by unequal crossing over or some comparable mechanism. The investigator will test these and other hypotheses by comparing the architecture of the MSP complex between various strains of C. elegans and other species in the same genus. The mechanisms of gene family evolution are formulated in terms of population genetics but the comparative methodology, to include stimating phylogenies for gene families, draws heavily on the principles of systematic biology, whereas a major goal is to understand the structure of this important class of eukaryotic genes; thus, this research is truly interdisciplinary.