Ecological adaptation in the Galápagos sea lion: The role of foraging ontogeny and interspecific competition

• Applicant: Professor Dr. Fritz Trillmich
• Subject Area: Sensory and Behavioural Biology
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 81016557

Environmental conditions during early development greatly influence later habitat choice, foraging behavior, and settlement patterns of juvenile animals. Such early influences may enable ecological separation within a population. We have previously demonstrated differences in food choice, morphology of the feeding apparatus, and genetic make-up of Galapagos sea lions (GSL; Zalophus wollebaeki) from the western and central populations of the archipelago. Such differences were unexpected given the high mobility of this species relative to its small geographical range. This difference between the western and central population may be caused by habitat differences as well as competition with Galapagos fur seals (GFS; Arctocephalus galapagoensis) that occur predominantly in the west. We here suggest to study the development of foraging behavior and area-use by young sea lions as well as potential competition with fur seals to determine the contribution of environmental differences during ontogeny to ecological adaptation in western and central populations. This should show how habitat use correlates with differences in foraging and how these differences become established during ontogeny. In addition, the study will determine the role of foraging ontogeny for juvenile survival and if competition with the sympatric GFS can explain that the western GSL population that lives in more productive waters is less abundant than that in the less productive central area. The study will thereby contribute to understanding the role of ontogenetic experience and interspecific competition for habitat choice, population dynamics, and the early stages of speciation.

• DFG Programme: Research Grants