Literaturdatenbank
Literaturdatenbank |
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Bennett, A. M., Keevil, M., & Litzgus, J. D. (2009). Demographic differences among populations of northern map turtles (graptemys geographica) in intact and fragmented sites. Canadian Journal of Zoology, 87(12), 1147–1157.
Added by: Sarina Wunderlich (28 Feb 2010 12:07:03 UTC) |
| Resource type: Journal Article BibTeX citation key: Bennett2009a View all bibliographic details  |
Categories: General Keywords: Emydidae, Graptemys, Graptemys geographica, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises Creators: Bennett, Keevil, Litzgus Collection: Canadian Journal of Zoology |
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| Abstract |
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Habitat fragmentation is a leading cause of reptile declines worldwide. We examined demographic differences between populations of Northern Map Turtles, Graptemys geographica (Le Sueur, 1817), inhabiting intact and fragmented sites along the Trent-Severn Waterway (TSW) in Ontario over two field seasons. We examined population densities, sex ratios, body size, and growth rates in two control sites and two fragmented sites (where the waterway is disrupted by dams). We predicted that population density would be higher in control sites, and that sex ratios would differ among sites. Abundance was greater than expected, but densities could not be compared owing to a lack of recaptures. Sex ratios in control sites were slightly male-biased and were significantly female-biased in fragmented sites. Turtles in fragmented habitats were significantly smaller than those in control habitats. Estimated growth rates of juveniles and males were significantly reduced in fragmented populations compared with controls. We hypothesize that habitat alterations in fragmented sites are differentially affecting demographic classes because of the intersexual niche divergence observed in Map Turtles. We emphasize the need for further research to examine the interactions between habitat alteration and invasive species and the effects they are having on Northern Map Turtle populations.
Added by: Sarina Wunderlich |