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- Title
Size, sex and individual-level behaviour drive intrapopulation variation in cross-ecosystem foraging of a top-predator.
- Authors
Nifong, James C.; Layman, Craig A.; Silliman, Brian R.; Bearhop, Stuart
- Abstract
Large-bodied, top-predators are often highly mobile, with the potential to provide important linkages between spatially distinct food webs. What biological factors contribute to variation in cross-ecosystem movements, however, have rarely been examined., Here, we investigated how ontogeny (body size), sex and individual-level behaviour impacts intrapopulation variation in cross-ecosystem foraging (i.e. between freshwater and marine systems), by the top-predator Alligator mississippiensis., Field surveys revealed A. mississippiensis uses marine ecosystems regularly and are abundant in estuarine tidal creeks (from 0·3 to 6·3 individuals per km of creek, n = 45 surveys). Alligator mississippiensis captured in marine/estuarine habitats were significantly larger than individuals captured in freshwater and intermediate habitats., Stomach content analysis (SCA) showed that small juveniles consumed marine/estuarine prey less frequently (6·7% of individuals) than did large juveniles (57·8%), subadult (73%), and adult (78%) size classes. Isotopic mixing model analysis ( SIAR) also suggests substantial variation in use of marine/estuarine prey resources with differences among and within size classes between sexes and individuals (range of median estimates for marine/estuarine diet contribution = 0·05-0·76)., These results demonstrate the importance of intrapopulation characteristics (body size, sex and individual specialization) as key determinants of the strength of predator-driven ecosystem connectivity resulting from cross-ecosystem foraging behaviours. Understanding the factors, which contribute to variation in cross-ecosystem foraging behaviours, will improve our predictive understanding of the effects of top-predators on community structure and ecosystem function.
- Subjects
PREDATORY animals; BODY size; ANIMAL sexual behavior; PREDATORY animal behavior; HABITATS; FRESHWATER habitats
- Publication
Journal of Animal Ecology, 2015, Vol 84, Issue 1, p35
- ISSN
0021-8790
- Publication type
Article
- DOI
10.1111/1365-2656.12306