Meeting Abstract

67.1  Jan. 7  The energetic consequences for prey specialist and generalist populations in the garter snakes Thamnophis elegans, T. couchii and T. ordinoides. BRITT, E.J.*; HICKS, J.W.; BENNETT, A.F.; Univ. of California, Irvine ebritt@uci.edu

The Western Terrestrial garter snake, T. elegans, exists in two geographically isolated populations in northern California: a coastal population with a specialized diet of slugs and an inland population with a generalized diet of fish, anurans, mice and leeches. To test whether or not the coastal slug eaters have an energetic advantage over the inland generalists when digesting slugs, we have shown that the snakes from the specialized coastal populations assimilate more net energy from a slug diet than do the generalist snakes. Recently, we have expanded our comparison to include closely related garter snake species considered to be dietary specialists on slugs (T. ordinoides) and fish (T. couchii). We tested the hypothesis that dietary specialization of garter snakes is accompanied by increased digestive efficiency compared to generalist garter snakes, when feeding on specialized prey types. From our results, there is evidence to suggest that this group of garter snakes exhibit larger differences in digestive efficiency on the lower quality prey item (slugs) than the more common prey item (fish). Slug specialist T. ordinoides and T. elegans both digested slugs better than generalist T. elegans and T. couchii. However, digestive efficiency was more similar between the different groups of snakes when feeding on fish. This study was supported by NSF grant IBN 9727762 awarded to A.F.B and J.W.H. and by NSF grant IOB 0445680 awarded to J.W.H.