Local variation of within-host clonal diversity coupled with genetic homogeneity in a marine trematode

Despite their ubiquity and importance to intertidal ecosystems, information is currently lacking regarding the genetic diversity of trematode parasites within coastal organisms and the distribution of their genetic variation among intertidal habitats. In this study, we quantiWed the clonal diversity of the coastal marine trematode Maritrema novaezealandensis within Zeacumantus subcarinatus snail hosts from three coastal bays in Otago Harbour, New Zealand, using Wve microsatellite loci to determine if diVerences exist in the frequency of occurrence of multi-clone infections. In addition, we examined gene Xow among M. novaezealandensis collected from the three bays. The frequency of mixed-clone infections varied fourfold among bays and no genetic diVerentiation was detected among intertidal bays. Across the coastal bays studied, M. novaezealandensis comprises a single population that is potentially infecting multiple Z. subcarinatus populations with varying life history traits.