Sexy Snails and Expensive Males

What are males good for? A study published this month in the journal Molecular Biology and Evolution provided new insights into one of the many benefits of sexual reproduction. The research, conducted out of the University of Iowa’s Roy J. Carver Center for Comparative Genomics, examined the mitochondrial genomes of a freshwater snail species in order to compare the rates at which genetic mutations accumulate during sexual and asexual reproduction.

The freshwater snail Potamopyrgus antipodarum is unique in that it can reproduce either sexually or asexually. In their native range male and female snails reproduce via sex; however, in places like the U.S. populations of P. antipodarum are clonal – they’ve been established by invasive and asexual females. By counting-up mutations and comparing the mitochondrial DNA of populations derived from sexually functional males to those populations founded completely by parthenogenic females, researchers were able to demonstrate that genetic recombination through sex effectively removed mutations from the snail genome.

The removal of potentially harmful mutations (‘purifying selection’) from a population is a benefit that may help explain why the expenses associated with sex are maintained by evolution. See, males do have value!!!

Neiman, M., Hehman, G., Miller, J., Logsdon, J., & Taylor, D. (2009). Accelerated Mutation Accumulation in Asexual Lineages of a Freshwater Snail Molecular Biology and Evolution DOI: 10.1093/molbev/msp300