Effects of polyploidy and reproductive mode on life history trait expression. Issue 3 (11th January 2016)

• Record Type: Journal Article
• Authors: Larkin, Katelyn; Tucci, Claire; Neiman, Maurine
• Is Part Of: Ecology and evolution. Volume 6:Issue 3(2016:Feb.)
• Page Start: 765
• Page End: 778
• Publication Date: 2016-01-11
• Subjects: Asexuality -- genomic variation -- mating system -- organismal ecology -- phenotypic variation -- ploidy level; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.1934
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Ploidy elevation is increasingly recognized as a common and important source of genomic variation. Even so, the consequences and biological significance of polyploidy remain unclear, especially in animals. Here, our goal was to identify potential life history costs and benefits of polyploidy by conducting a large multiyear common garden experiment in Potamopyrgus antipodarum, a New Zealand freshwater snail that is a model system for the study of ploidy variation, sexual reproduction, host–parasite coevolution, and invasion ecology. Sexual diploid and asexual triploid and tetraploid P. antipodarum frequently coexist, allowing for powerful direct comparisons across ploidy levels and reproductive modes. Asexual reproduction and polyploidy are very often associated in animals, allowing us to also use these comparisons to address the maintenance of sex, itself one of the most important unresolved questions in evolutionary biology. Our study revealed that sexual diploid P. antipodarum grow and mature substantially more slowly than their asexual polyploid counterparts. We detected a strong negative correlation between the rate of growth and age at reproductive maturity, suggesting that the relatively early maturation of asexual polyploid P. antipodarum is driven by relatively rapid growth. The absence of evidence for life history differences between triploid and tetraploid asexuals indicates that ploidy elevation is unlikely to underlie the differences in trait values that we detected between sexual and asexual snails. Finally, we found that sexual P. antipodarum did not experience discernable phenotypic variance‐related benefits of sex and were more likely to die before achieving reproductive maturity than the asexuals. Taken together, these results suggest that under benign conditions, polyploidy does not impose obvious life history costs in P. antipodarum and that sexual P. antipodarum persist despite substantial life history disadvantages relative to their asexual counterparts. Abstract : Why genomes are so variable in size and structure is a central unanswered question in biology. Here, we performed a powerful common garden experiment aimed at determining whether a common means of genomic change, ploidy elevation, affects key life history traits in a New Zealand freshwater snail. Our results suggest that under benign conditions, higher ploidy level does not impose obvious life history consequences in these snails, one of the first results of direct relevance to evaluating the consequences of ploidy elevation in a nonhybrid animal system.