Size, sex and individual-level behaviour drive intrapopulation variation in cross-ecosystem foraging of a top-predator.


Journal Article

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.

Full Text

Duke Authors

Cited Authors

  • Nifong, JC; Layman, CA; Silliman, BR

Published Date

  • January 2015

Published In

Volume / Issue

  • 84 / 1

Start / End Page

  • 35 - 48

PubMed ID

  • 25327480

Pubmed Central ID

  • 25327480

Electronic International Standard Serial Number (EISSN)

  • 1365-2656

International Standard Serial Number (ISSN)

  • 0021-8790

Digital Object Identifier (DOI)

  • 10.1111/1365-2656.12306


  • eng