The above map I put together based on the summary paper by Jass (2004). In this paper, she echoes the call of Hubricht (1985) and others that much of the upper midwest is woefully undersurveyed for snail abundance. Notice the large number of Wisconsin counties with fewer than five land snail species reported for that county. The most populous counties (Dane, Milwaukee, Brown), those with state universities within them, have the highest abundance. This is definitely not a result of natural distribution - I've found snails in counties that have no official records. It likely reflects the fact that the researchers concentrated their efforts close to home. What does this mean? If we want to know the true extent of the distribution of snails on this continent, we need more people looking for snails. They are an excellent indicator species and have a great deal to tell us about the modern (and ancient) environment if we'd only stop to listen.
Have you seen the Moerman & Estabrook paper in J. Biogeogr. looking at the relationship between the distribution of universities and angiosperm diversity?
ReplyDeleteThere's only one thing for it: we need more biologists!
Very informative site. I do hope you'll be back to posting soon!
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Greetings from north central WA State. We've got Vallonia, Discus, and tiny turbonate snails on a silty-sandy kame terrace here. The elev. is only 900 feet and it ain't all that cold so they're probably fossils. They look like fossils.
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