Literaturdatenbank
Literaturdatenbank |
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Gravel, M.-A. (2006). Sexual size dimorphism and diet specialization in the common map turtle (graptemys geographica). Unpublished thesis , University of Ottawa.
Added by: Sarina Wunderlich (25 Jan 2011 10:32:00 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Gravel2006 View all bibliographic details  |
Categories: General Keywords: Emydidae, Ernährung = nutrition, Graptemys, Graptemys geographica, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Systematik = taxonomy Creators: Gravel Publisher: University of Ottawa |
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| Abstract |
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Sexual size dimorphism may arise from sexual selection where one sex gains a reproductive advantage from being larger, or natural selection such as diet divergence, or both. In the common map turtle (Graptemys geographica), females are much larger than males, often exceeding twice their size. Extreme female-biased sexual size dimorphism has been hypothesized to be a result of natural selection for diet divergence. The goal of our study is to test the hypothesis that male and female map turtles specialize on different prey type and size. We also want to examine whether head width is a better predictor of consumed prey size. We collected fecal samples of adult females, juvenile females and adult males. Prey size can be reconstructed from mussel septa length and snail opercula length that are passed with the feces. The two sexes are consuming different prey, as well as different prey size. Females had significantly more zebra mussels in their fecal samples than males. Mollusc prey size increased with body size for females but not for males, while tricoptera prey size was independent of body size for both sexes. Residual head width is not positively related to mollusc prey type. Adult females consumed larger prey than adult males but juvenile females did not consume larger prey than same-sized males.
Added by: Sarina Wunderlich |