Between migration load and evolutionary rescue: dispersal, adaptation and the response of spatially structured populations to environmental change.
The evolutionary potential of populations is mainly determined by population size and available genetic variance. However, the adaptability of spatially structured populations may also be affected by dispersal: positively by spreading beneficial mutations across sub-populations, but negatively by moving locally adapted alleles between demes. We develop an individual-based, two-patch, allelic model to investigate the balance between these opposing effects on a population's evolutionary response to rapid climate change. Individual fitness is controlled by two polygenic traits coding for local adaptation either to the environment or to climate. Under conditions of selection that favour the evolution of a generalist phenotype (i.e. weak divergent selection between patches) dispersal has an overall positive effect on the persistence of the population. However, when selection favours locally adapted specialists, the beneficial effects of dispersal outweigh the associated increase in maladaptation for a narrow range of parameter space only (intermediate selection strength and low linkage among loci), where the spread of beneficial climate alleles is not strongly hampered by selection against non-specialists. Given that local selection across heterogeneous and fragmented landscapes is common, the complex effect of dispersal that we describe will play an important role in determining the evolutionary dynamics of many species under rapidly changing climate.
The James Hutton Institute, , Craigiebuckler, Aberdeen AB15 8QH, UK, Institute of Biological and Environmental Sciences, University of Aberdeen, , Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, UK, Institute für Biologie-Botanik, Freie Universität Berlin, , Altensteinstrasse 6, Berlin 14195, Germany, Evolution, Modeling and Analyses of Biodiversity group, Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, , Grenoble Cedex 9, France.
Elizabeth C
EC
Bourne
Greta
G
Bocedi
Justin M J
JM
Travis
Robin J
RJ
Pakeman
Rob W
RW
Brooker
Katja
K
Schiffers
D025041:Animal Migration; D005075:Biological Evolution; D057231:Climate Change; D051456:Gene Flow; D008040:Genetic Linkage; D014644:Genetic Variation; D010641:Phenotype; D011157:Population Dynamics; D012641:Selection, Genetic
allelic model; gene flow; linkage; local adaptation; meta-populations