CONTEMPORARY EVOLUTION OF SEA URCHIN GAMETE-RECOGNITION PROTEINS: EXPERIMENTAL EVIDENCE OF DENSITY-DEPENDENT GAMETE PERFORMANCE PREDICTS SHIFTS IN ALLELE FREQUENCIES OVER TIME
Version of Record online: 29 MAR 2012
© 2012 The Author. Evolution © 2012 The Society for the Study of Evolution.
Volume 66, Issue 6, pages 1722–1736, June 2012
How to Cite
Levitan, D. R. (2012), CONTEMPORARY EVOLUTION OF SEA URCHIN GAMETE-RECOGNITION PROTEINS: EXPERIMENTAL EVIDENCE OF DENSITY-DEPENDENT GAMETE PERFORMANCE PREDICTS SHIFTS IN ALLELE FREQUENCIES OVER TIME. Evolution, 66: 1722–1736. doi: 10.1111/j.1558-5646.2012.01608.x
- Issue online: 1 JUN 2012
- Version of Record online: 29 MAR 2012
- Accepted manuscript online: 21 FEB 2012 02:51PM EST
- Received August 17, 2011, Accepted December 1, 2011, Data Archived: Dryad: doi: 10.5061/dryad.0k2469h8
- Density-dependent selection;
- fertilization success;
- frequency-dependent selection;
- sexual conflict;
- sperm bindin
Species whose reproductive strategies evolved at one density regime might be poorly adapted to other regimes. Field and laboratory experiments on the sea urchin Strongylocentrotus franciscanus examined the influences of the two most common sperm-bindin alleles, which differ at two amino acid sites, on fertilization success. In the field experiment, the arginine/glycine (RG) genotype performed best at low densities and the glycine/arginine (GR) genotype at high densities. In the laboratory experiment, the RG genotype had a higher affinity with available eggs, whereas the GR genotype was less likely to induce polyspermy. These sea urchins can reach 200 years of age. The RG allele dominates in larger/old sea urchins, whereas smaller/younger sea urchins have near-equal RG and GR allele frequencies. A latitudinal cline in RG and GR genotypes is consistent with longer survival of sea urchins in the north and with predominance of RG genotypes in older individuals. The largest/oldest sea urchins were likely conceived at low densities, before sea-urchin predators, such as sea otters, were overharvested and sea-urchin densities exploded off the west coast of North America. Contemporary evolution of gamete-recognition proteins might allow species to adapt to shifts in abundances and reduces the risk of reproductive failure in altered populations.