Literaturdatenbank
Literaturdatenbank |
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Bennett, A. M. (2009). Effects of habitat fragmentation on the spatial ecology and genetics of northern map turtles (graptemys geographica). Unpublished thesis , Laurentian University, Sudbury, Ontario.
Added by: Admin (29 Jan 2012 12:38:34 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Bennett2009b View all bibliographic details  |
Categories: General Keywords: Emydidae, Graptemys, Graptemys geographica, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises Creators: Bennett Publisher: Laurentian University (Sudbury, Ontario) |
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| Abstract |
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I examined the effects of habitat fragmentation by locks and dams on an at-risk aquatic turtle species, the Northern Map Turtle ('Graptemys geographica'), on the Trent-Severn Waterway, Ontario, Canada. I investigated the demography, spatial ecology, and population genetics of Map Turtles in both fragmented and unfragmented habitats. Demographic differences in fragmented populations included strongly female-biased sex ratios, smaller turtles, and reduced growth rates among males and juveniles. I hypothesize that habitat alterations in fragmented sites are differentially affecting age/sex classes because of the intersexual niche divergence found in Map Turtles. Map Turtle movements are significantly decreased in areas bounded by locks and dams. These barriers to movement are not impermeable, however, as I have documented three cases of turtles either locking through or walking (during nesting) around a lock and dam. Map Turtle populations on the TSW do not exhibit the genetic consequences expected in fragmented landscapes. However, the small spatial scale and short time period since the construction of the locks and dams (about 100 years) may mean that genetic data are reflecting historical, and not current, population genetic structure, or that the low resolution of genetic data is resulting in a false negative. Alternatively, locks may allow movement between habitats fragmented by a dam, reducing the impacts of genetic drift. This study demonstrates the importance of examining conservation issues from multiple perspectives in order to understand current impacts and predict future responses.
Added by: Admin |