For purposes of the study, the snail populations were grown, fed, and maintained in laboratory conditions in order to eliminate the effects of other variables.
Neiman and Zachar also detected a so-called "Goldilocks" effect, in which too few or too many snails living together could adversely affect reproduction. This possibility is especially intriguing in light of another 2013 study by Neiman's group, which showed that the reproductive output of these snails can be controlled by simply exposing the snails to water conditioned by other snails, suggesting that reproduction in these invasive snails is affected by waterborne, snail-produced chemicals.
"While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos," Neiman says.
"These results indicate that there are profound and complex relationships between population density, growth rate, and embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology," she says.
In 2011, Neiman, together with UI colleagues John M. Logsdon Jr., UI associate professor of biology, and collaborator Jeffrey Boore of the University of California, Berkeley, received a four-year, $876,752 grant from the National Science Foundation. That research, which uses both sexual and asexually reproducing representatives of the snail species, tests ideas of why sexual reproduct
|Contact: Gary Galluzzo|
University of Iowa