LOW RATES OF BINDIN CODON EVOLUTION IN LECITHOTROPHIC HELIOCIDARIS SEA URCHINS
Article first published online: 1 APR 2012
© 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.
Volume 66, Issue 6, pages 1709–1721, June 2012
How to Cite
Hart, M. W., Popovic, I. and Emlet, R. B. (2012), LOW RATES OF BINDIN CODON EVOLUTION IN LECITHOTROPHIC HELIOCIDARIS SEA URCHINS. Evolution, 66: 1709–1721. doi: 10.1111/j.1558-5646.2012.01606.x
- Issue published online: 1 JUN 2012
- Article first published online: 1 APR 2012
- Accepted manuscript online: 21 FEB 2012 02:45PM EST
- Received June 9, 2011, Accepted November 10, 2011
- sexual selection
Life-history variables including egg size affect the evolutionary response to sexual selection in broadcast-spawning sea urchins and other marine animals. Such responses include high or low rates of codon evolution at gamete recognition loci that encode sperm- and egg-surface peptides. Strong positive selection on such loci affects intraspecific mating success and interspecific reproductive divergence (and may play a role in speciation). Here, we analyze adaptive codon evolution in the sperm acrosomal protein bindin from a brooding sea urchin (Heliocidaris bajulus, with large eggs and nonfeeding or lecithotrophic larval development) and compare our results to previously published data for two closely related congeners. Purifying selection and low relative rates of bindin nonsynonymous substitution in H. bajulus were significantly different from selectively neutral bindin evolution in H. erythrogramma despite similar large egg size in those two species, but were similar to the background rate of nonsynonymous bindin substitution for other closely related sea urchins (including H. tuberculata, all with small egg size and feeding planktonic larval development). Bindin evolution is not driven by egg size variation among Heliocidaris species, but may be more consistent with an alternative mechanism based on the effects of high or low spatial density of conspecific mates.