Meeting Abstract

31.1  Friday, Jan. 4  Endoparasitic infections in the red-sided garter snake, Thamnophis sirtalis parietalis UHRIG, E.J.*; FRIESEN, C.R.; MASON, R.T.; Oregon State University; Oregon State University; Oregon State University

Garter snakes have been model organisms for numerous studies of reproductive behavior, endocrinology, and chemical ecology. Such aspects of biology are known to be affected by parasites in a variety of other organisms yet parasite-mediated effects have been little studied in garter snakes. Indeed, even the composition of parasite communities has not been well described for most Thamnophis species including the red-sided garter snake. Our current study presents data on the prevalence and intensity of endoparasitic infections in red-sided garter snakes, specifically two distinct populations in Manitoba, Canada; thus we are able to make both inter- and intrapopulational comparisons. Snakes from both populations harbor at least five genera of endoparasites including nematodes (Rhabdias sp.) and trematodes (Lechriorchis sp.) in the lung, cestodes in the digestive tract, and trematode mesocercariae concentrated in the visceral fat deposits (Fibricola sp.) and the tail tissue (Alaria sp.). We investigate patterns of parasite distribution including potential variation in infection prevalence and intensity based on host sex and body size. We also examine whether measures of infection are correlated with host fat stores and/or reproductive structures. Of particular interest is our finding that, in at least one host population, the presence of Lechriorchis trematodes is negatively associated with ductus deferens mass suggesting potential implications for male reproductive investment. The results of this study provide an important basis for future work investigating parasite-mediated fitness effects in garter snakes.