Yesterday was a good day for a field trip, despite the heat and the humidity—and the abundant poison ivy everywhere. We surveyed the vicinity of the location where Cepaea nemoralis had recently been discovered (see part 1). We found additional colonies constituting what appears to be one widespread population.
The shell colors and band numbers of Cepaea nemoralis are notoriously polymorphic (Evolution MegaLab has a brief introduction). Various environmental (temperature, etc.) and biological (predators) factors are believed to influence the distributions of shell color and banding types in different habitats. The evolutionary implications of Cepaea nemoralis polymorphism have been studied for decades (again, check out the Evolution MegaLab pages for introductory information).
We found both empty shells and live specimens of 3 banding varieties all with yellow shells. There were unbanded snails and 5-banded snails.
And then there were 1-banded snails.
To better delineate the range of the species in our study area, we are planning further field trips on future hot and humid days. Watch this blog for updates.