In today’s Academic Minute, Dr. Matthew Gilg of the University of North Florida reveals what reproduction between diverging species has to teach us about evolution.
Matthew Gilg is an associate professor of biology at the University of North Florida. His research is focused on a variety of evolutionary questions including the genetics and process of speciation, species interactions, and hybridization. He is currently overseeing several projects examining breeding among divergent species in northern Florida. He earned his Ph.D. at the University of South Carolina.
Dr. Matthew Gilg – Reproduction and Speciation
My primary area of interest is in figuring out how populations that have diverged from a common ancestor can become incapable of reproducing with each other. Many terrestrial species have distinct reproductive behaviors that keep them from mating with other species. Or they may have reproductive organs that are incompatible. In many marine invertebrates, however, species often simply release their sperm and eggs into the water column where fertilization may take place. In these species it is thought that reproductive incompatibility evolves due to divergence of proteins involved in the interaction between sperm and egg during fertilization. I am currently studying whether different versions of a sperm protein called M7 lysin, affect the ability of those sperm to fertilize eggs of the same species, as well as eggs of a different species.
These experiments are done in two species of blue mussels, Mytilus edulis and Mytilus galloprovincialis, which hybridize in some parts of Europe. Using genetic techniques my students and I determine which variant of sperm protein each male has and then we set up experiments where we measure the fertilization success of those sperm when they are the only male contributing sperm, as well as when they are in competition with sperm from another male.
Thus far our results suggest that all sperm fertilize eggs of both species with equal efficiency when not in competition with sperm from other males. When in competition, however, the sperm of Mytilus galloprovincialis is actually better at fertilizing eggs of both species, even when competing against sperm of Mytilus edulis. Sperm from Mytilus galloprovincialis that have different variants of the sperm protein M7 lysin, however, do not differ in their ability to fertilize eggs of either species. This suggests that variation at M7 lysin probably doesn’t play a role in becoming reproductively incompatible in these species.