This book provides a comprehensive review of the ecology of freshwater bivalves and gastropods worldwide. It deals with the ecology of these species in its broadest sense, including diet, habitat and reproductive biology, emphasising in particular the tremendous diversity of these freshwater invertebrates. Following on from these introductory themes, the author develops a life history model that unifies them, and serves as a basis for reviews of their population and community ecology, including treatments of competition, predation, parasitism and biogeography. Extensively referenced and providing a synthesis of work from the nineteenth century onwards, this book includes original analyses that seek to unify previous work into a coherent whole. It will appeal primarily to professional ecologists and evolutionary biologists, as well as to parasitologists.

Abstract. It has long been speculated that Physa acuta, a pulmonate snail widespread and invasive in fresh waters of the old world, may have originated in North America. But the identification of a new‐world cognate has been complicated by the confused systematics and taxonomy of the Physidae in America. More than 40 species of physids are currently recognized in the United States, many with variable and overlapping morphology. We have previously established that premating reproductive isolation is negligible among physid snails. Here we report the results from no‐choice crosses each involving 2 populations of the widespread American species Physa heterostropha and Physa integra, both with each other and with P. acuta, designed to compare measures of reproductive success between species and between populations within species. Samples of P. acuta were collected from France and Ireland, P. heterostropha from eastern Pennsylvania and South Carolina, and P. integra from southern Indiana and northern Michigan. The 6 intrapopulation controls varied quite significantly in their survival, age at first reproduction, parental fecundity, F1 viability, and F1 fertility under our culture conditions. Measures of survival and reproduction in the 6 interpopulation crosses were generally intermediate, but in no case significantly worse than the more poorly performing control. Thus we were unable to detect evidence of reproductive isolation among our 6 populations of snails from 2 continents. All should be referred to the oldest available nomen, P. acuta.

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Land use change is one of the most commonly cited contributing factors to infectious disease emergence, yet the mechanisms responsible for such changes and the spatial scales at which they operate are rarely identified. The distributions of parasites with complex life cycles depend on interactions between multiple host species, suggesting the net effects of land use on infection patterns may be difficult to predict a priori. Here, we used an information-theoretic approach to evaluate the importance of land use and spatial scale (local, watershed, and regional) in determining the presence and abundance of multi-host trematodes of amphibians. Among 40 wetlands and 160 hosts sampled, trematode abundance, species richness, and the presence and abundance of pathogenic species were strongly influenced by variables at the watershed and regional scales. Based on model averaging results, overall parasite richness and abundance were higher in forested wetlands than in agricultural areas; however, this pattern was influenced by a wetland's proximity to the Mississippi Flyway at the regional scale. These patterns likely reflect the activity of trematode definitive hosts, such as mammals and especially birds, such that infections decreased with increasing distance from the Mississippi River. Interestingly, despite lower mean infections, agricultural wetlands had higher variances and maximum infections. At the wetland scale, phosphorus concentrations and the abundances of intermediate hosts, such as snails and larval amphibians, positively affected parasite distributions. Taken together, these results contribute to our understanding of how altered landscapes affect parasite communities and inform further research on the environmental drivers of amphibian parasite infections.

Managing invasive species requires information about their distributions and potential effects, but community-level impacts of invasive animals remain poorly understood.

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