Evol Ecol Res 4: 219-226 (2002)     Full PDF if your library subscribes.

Temporal and spatial distributions of parasites and sex in a freshwater snail

Curtis M. Lively1* and Jukka Jokela2

1Department of Biology, Indiana University, Bloomington, IN 47405-3700, USA and 2Department of Biology, University of Oulu, FIN-90014, Finland

Author to whom all correspondence should be addressed.
e-mail: clively@indiana.edu

ABSTRACT

The Red Queen hypothesis predicts that sexual reproduction should be favoured in geographic locations where the risk of infection is high. We surveyed 20 lakes on the South Island of New Zealand to determine whether an association exists between the presence of individuals sterilized by trematode larvae and the presence of males in a common freshwater snail (Potamopyrgus antipodarum). The snail is unique in that populations are often mixtures of triploid asexual females that reproduce by apomictic parthenogenesis and diploid sexual individuals that reproduce by cross-fertilization. We compared the results to a similar study conducted over 10 years ago. The results showed a highly significant correlation between the frequency of males in the past and present data. In addition, the results showed a strong significant correlation between the prevalence of trematodes in past and present data sets, indicating that any selection imposed by the parasites has remained reasonably constant. Finally, the frequency of males averaged over both data sets was significantly and positively correlated with the mean frequency of infected individuals. These results suggest that infection levels and male frequency may be relatively stable and that parasites may be a factor in selecting for sexual reproduction.

Keywords: Microphallus, New Zealand, Potamopyrgus antipodarum, Red Queen hypothesis, sexual reproduction.

DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.

 

        © 2002 Curtis M. Lively. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.