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

摘要: 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 South Island New Zealand to determine whether an association exists between presence individuals sterilized by trernatode larvae and males a common freshwater snail (Potamopyrgus artipodarum). unique populations are often mixtures triploid asexual females reproduce apomictic parthenogenesis diploid cross-fertilization. compared results similar study conducted over 10 years ago. showed highly significant correlation frequency past present data. In addition, strong prevalence trematodes data sets, indicating any selection imposed parasites has remained reasonably constant. Finally, averaged both sets was significantly positively correlated with mean infected individuals. These suggest levels male may relatively stable factor selecting for reproduction.