Selection against immigrants in wild seabird populations
Résumé
Immigration is a major demographic parameter shaping population dynamics and is an important
driver of eco-evolutionary patterns, but the fitness consequences for individuals following their
settlement to a new population (immigrants) remain poorly tested in wild animal populations,
particularly among long-lived species. Here we show that immigrants have a lower fitness than
residents in three wild seabird populations (wandering albatross Diomedea exulans, southern fulmar
Fulmarus glacialoides, snow petrel Pagodroma nivea). Across all species and during a 32-year
period, immigrants made on average 9 to 29% fewer breeding attempts, had 5–31% fewer fledglings,
had 2–16% lower breeding success and produced 6–46% fewer recruits. Female immigration
and male residency were also favored through differences in breeding performance. We provide
evidence for selection against immigrants in wild populations of long-lived species and our results
are consistent with female-biased dispersal in birds being driven by asymmetric limiting resources
and the competitive ability of dispersers vs. non-dispersers.