title: Rapid adaptive phenotypic change following colonization of a newly restored habitat.
abstract: Real-time observation of adaptive evolution in the wild is rare and limited to cases of marked, often anthropogenic, environmental change. Here we present the case of a small population of reed warblers (Acrocephalus scirpaceus) over a period of 19 years (1996-2014) after colonizing a restored wetland habitat in Malta. Our data show a population decrease in body mass, following a trajectory consistent with a population ascending an adaptive peak, a so-called Ornstein-Uhlenbeck process. We corroborate these findings with genetic and ecological data, revealing that individual survival is correlated with body mass, and more than half of the variation in mean population fitness is explained by variation in body mass. Despite a small effective population size, an adaptive response has taken place within a decade. A founder event from a large, genetically variable source population to the southern range margin of the reed warbler distribution likely facilitated this process.
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P. O. Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Camilla
authors.initials: C
authors.lastname: Lo Cascio Sætre
authors.affiliation: BirdLife Malta, Xemxija Waterfront Apartments, Flat ½, Triq Is-Simar, Xemxija SPB 9025, Malta.
authors.forename: Charles
authors.initials: C
authors.lastname: Coleiro
authors.affiliation: BirdLife Malta, Xemxija Waterfront Apartments, Flat ½, Triq Is-Simar, Xemxija SPB 9025, Malta.
authors.forename: Martin
authors.initials: M
authors.lastname: Austad
authors.affiliation: BirdLife Malta, Xemxija Waterfront Apartments, Flat ½, Triq Is-Simar, Xemxija SPB 9025, Malta.
authors.forename: Mark
authors.initials: M
authors.lastname: Gauci
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P. O. Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Glenn-Peter
authors.initials: GP
authors.lastname: Sætre
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P. O. Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Kjetil Lysne
authors.initials: KL
authors.lastname: Voje
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P. O. Box 1066 Blindern, N-0316 Oslo, Norway.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Eroukhmanoff
mesh_terms: D000818:Animals; D049628:Body Size; D017753:Ecosystem; D005260:Female; D008297:Male; D010641:Phenotype; D020308:Songbirds / Q000254:growth & development / Q000502:physiology*; D053833:Wetlands