title: Rapid trait evolution drives increased speed and variance in experimental range expansions.
abstract: Range expansions are central to two ecological issues reshaping patterns of global biodiversity: biological invasions and climate change. Traditional theory considers range expansion as the outcome of the demographic processes of birth, death and dispersal, while ignoring the evolutionary implications of such processes. Recent research suggests evolution could also play a critical role in determining expansion speed but controlled experiments are lacking. Here we use flour beetles (Tribolium castaneum) to show experimentally that mean expansion speed and stochastic variation in speed are both increased by rapid evolution of traits at the expansion edge. We find that higher dispersal ability and lower intrinsic growth rates evolve at the expansion edge compared with spatially nonevolving controls. Furthermore, evolution of these traits is variable, leading to enhanced variance in speed among replicate population expansions. Our results demonstrate that evolutionary processes must be considered alongside demographic ones to better understand and predict range expansions.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309, USA.|Biofrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Weiss-Lehman
authors.affiliation: Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado 80523-1177, USA.|Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado 80523, USA.|UMR Centre de Biologie et Gestion des Populations, INRA, 34988 Montferrier sur Lez, France.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Hufbauer
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Brett A
authors.initials: BA
authors.lastname: Melbourne
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D057231:Climate Change; D005260:Female; D008297:Male; D008954:Models, Biological; D010641:Phenotype; D011157:Population Dynamics; D012737:Sex Factors; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013997:Time Factors; D014231:Tribolium / Q000502:physiology*