"The results were that zebra mussels produced byssal threads at about twice the rate of quagga mussels," Peyer says. "Zebra mussels can ramp up their byssal thread production under different flows."
A statistical model Peyer developed also predicted that, with increasing velocity, zebra mussels produce more threads than quagga mussels.
According to this model, the zebra mussels show high plasticity, or the ability to adapt to changing environmental conditions. Plasticity can be an adaptive characteristic that allows an organism to survive under new conditions. In this case, the new condition is increased flow.
Zebra mussels are also able to stay attached better. At the highest velocity, only 10 percent of the zebra mussels detached, but 60-70 percent of the quagga mussels detached.
Results from her research, funded by the UW-Madison Sea Grant Institute, is published in the July 1 issue of the Journal of Experimental Biology.
According to Peyer's research adviser, Professor Carol Eunmi Lee at the UW-Madison Center of Rapid Evolution, no one has previously looked at differences in attachment between these species as an explanation for their distribution patterns in North America.
"It's the first time somebody actually went and systematically looked at functional differences between the two species that would explain the different kinds of substrate that they could invade," she says. "In that sense, Suzanne has produced a really elegant and clever study. It has very concrete hypotheses and results."
Zebra mussels were first introduced in the Great Lakes in the late 1980s, hitchhiking their way into North America in the ballast water of ships from the Caspian and Black Seas. Within a few years, zebra mussels had c
|Contact: Suzanne Peyer|
University of Wisconsin-Madison