Table of Contents
International Journal of Evolutionary Biology
Volume 2011, Article ID 439046, 7 pages
http://dx.doi.org/10.4061/2011/439046
Research Article

Persistent Copulation in Asexual Female   Potamopyrgus antipodarum: Evidence for Male Control with Size-Based Preferences

Department of Biology, University of Iowa, 143 Biology Building, Iowa City, IA 52242-1324, USA

Received 30 September 2010; Revised 12 January 2011; Accepted 3 February 2011

Academic Editor: Jeremy Marshall

Copyright © 2011 Amanda E. Nelson and Maurine Neiman. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Transitions from sexual to asexual reproduction provide a useful context for investigating the evolutionary loss of nonfunctional traits. It is often assumed that useless behaviors or structures will degrade, but this process is poorly understood. Potamopyrgus antipodarum is an ancestrally sexual New Zealand freshwater snail characterized by numerous independent transitions to asexual all-female lineages. The availability of multiple independently-derived asexual lineages of various time since derivation from sexual ancestors means that the P. antipodarum system is well-suited for the study of trait loss related to mating behavior and copulation. Here, we asked whether mating behavior in asexual female P. antipodarum degrades with increasing asexual lineage age. While copulation frequency did not differ in females from old versus young asexual lineages, post hoc analyses indicated that it was instead positively associated with mean lineage female size. We observed that female P. antipodarum take a passive physical role in copulatory interactions, indicating that female behavior may not be a useful variable for detection of sex-related vestigialization in this system. Instead, males seem to be in proximate control of copulation frequencies, meaning that male mating behavior may be a primary determinant of the expression of mating behavior in asexual female P. antipodarum.