Evol Ecol Res 8: 753-763 (2006)     Full PDF if your library subscribes.

Prevalence of parasites does not predict age at first reproduction or reproductive output in the freshwater snail, Helisoma anceps

Amy C. Krist*

Department of Biology, University of Wisconsin-Eau Claire, Eau Claire, WI 54701, USA

Address all correspondence to Amy Krist, Department of Zoology and Physiology, Dept. 3166, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA.
e-mail: krist@uwyo.edu

ABSTRACT

Question: Are reproductive output and age at first reproduction explained by the prevalence of castrating parasites in a population? Life-history theory predicts this relationship.

Data studied: Reproductive output over 21 days in field-caught freshwater snails from 12 lake populations in Wisconsin. I also measured age at first reproduction and reproductive output over 27 weeks in laboratory-reared snails from the same populations. I determined the prevalence of parasites in each of 2 years as the proportion of snails infected with digenean trematodes.

Search method: Field-caught: I regressed mean reproductive output on mean prevalence. Laboratory-reared: I regressed mean reproductive output and mean age at first reproduction on mean prevalence.

Conclusions: Neither measure of reproductive output, nor age at first reproduction, was predicted by the mean prevalence of trematode parasites.

Keywords: age at first reproduction, castrating parasites, freshwater snails, life-history theory, reproductive output, trematodes.

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