Freshwater snails are common and familiar inhabitants of rivers, lakes, and streams throughout North America. In some environments they comprise the majority of the macroinvertebrate biomass, significantly influencing community composition, energy flow, and nutrient cycling. Yet their biology remains almost as obscure to the scientific community as to the lay public. Collected here in Volume 4 of the FWGNA series are 38 essays on the ecology and biogeography of North American freshwater gastropods, originally published in blog form 2003 - 2017, edited and rearranged thematically. Patterns of distribution are reviewed and analyzed at regional scales, with particular emphasis on mechanisms of dispersal. New invasions are reported, their progress monitored, and their consequences examined. The subjects of rarity and endemism, first introduced in Volume 3, are explored at greater depth in Volume 4 as well.
The scholarly study of biogeography has, in recent years, become entangled with public policies regarding endangered species conservation and invasive species control. Here we review several striking cases where natural resource agencies have been misled by conservation biologists biased by research funding. We suggest that the correct relationship between science and public policy is analogous to playing baseball and playing the banjo – neither compatible nor incompatible, neither better nor worse, just entirely different.