Contact: Professor Mark Dybdahl, School of Biological Sciences, 509-335-7909, dybdahl@wsu.edu
New Zealand Mud Snails
Alison Emblidge Fromme wraps snails in a paper towel to put in a cooler, Lake Poerua, South Island, New Zealand.
Potamopyrgus antipodarum is no ordinary snail, but of course I'm a little biased. In New Zealand, the snails are common in lakes scattered throughout the North and South Islands. Some are spiny, some are smooth, but they are all tiny-about the size of a lentil-and admittedly unimpressive at first glance. In these lakes, two types exist: those that reproduce sexually and those that reproduce asexually. Among the asexuals, hundreds of different lineages exist, whose offspring are genetically identical clones of the single female parent.
Only one of these clones has become invasive in the western U.S. Why? It was this question that led me down winding roads to hunt snails in remote New Zealand lakes. On the surface, collecting snails is a straightforward affair: walk knee-deep along the lake's edge, bend down, pick up a rock, brush snails into a net, and repeat ad nauseam. It was only after hours and hours of practice that I learned the subtler nuances, such as maximizing my speed, avoiding vegetation tangles in the net, and snorkeling for snails.
Sometimes the lakes were clear, the mountainous scenery was amazing, and I marveled that my research had brought me to such wonderful places. Other times, the rain poured down, the lakes were full of leeches, and I suffered for days from parasite-induced "duck itch," a condition resembling mosquito bites.
So why are some species-or in our case, one clone within a species-invasive? One hypothesis is that they have left their parasites, pathogens, and predators behind in their move to the U.S. Without natural enemies to keep their populations in check, the invaders proliferate. In New Zealand, 14 different parasite species infect the snails. In the U.S., none do.
Click here for the full story from Washington State Magazine.