Sperm morphology and function in passerine birds
Project Leader: Jan T. Lifjeld
Professor Raleigh J Robertson, Department of Biology, Queen’s University, Kingston, Ontario, Canada
Dr. Geir Rudolfsen, Institue of Artic and Marine Biology, University of Tromsø
Research Council of Norway, FRIBIO, 2006-2010 (project number 170853)
Description of Project:
The prime function of sperm cells is to fertilize eggs. Despite this common purpose, there is a tremendous diversity among animal taxa in sperm phenotypes. Part of the variation can be attributed to phylogenetic relatedness, and sperm are often used as diagnostic traits in taxonomy. But there is also increasing evidence that postcopulatory sexual selection, or sperm competition, is an important evolutionary force shaping sperm morphology in many taxa, including birds. The main goal of this project is to advance our understanding of the evolutionary processes that shape sperm morphology and diversity, and their function. We use passerine birds as model organisms, as we already know a good deal about their mating systems and general biology. The project has three sub-goals. First, we will investigate the relative roles of phylogeny and sperm competition for the evolution of sperm traits across a number of passerine families and genera, using levels of extrapair paternity as a proxy for the intensity of sperm competition. Second, we will study between-male variation in sperm morphology and its possible associations with mitochondrial and nuclear genotypes, and fertilization success under a regime of intense sperm competition. These analyses will be carried out in well-studied model systems. Finally, we will investigate the frequency of male infertility in selected species, in which we have prior indication that male infertility has an evolutionary significance for the mating system.