Abstract
Previous studies of adaptive evolution in sink habitats (in which isolated populations of a species cannot persist deterministically) have highlighted the importance of demographic constraints in slowing such evolution, and of immigration in facilitating adaptation. These studies have relied upon either single-locus models or deterministic quantitative genetic formulations. We use individual-based simulations to examine adaptive evolution in a 'black-hole' sink environment where fitness is governed by a polygenic character. The simulations track both the number of individuals and their multi-locus genotypes, and incorporate, in a natural manner, both demographic and genetic stochastic processes. In agreement with previous studies, our findings reveal the central parts played by demographic constraints and immigration in adaptation within a sink (adaptation is more difficult in environments with low absolute fitness, and higher immigration can accelerate adaptation). A novel finding is that there is a 'punctuational' pattern in adaptive evolution in sink environments. Populations typically stay maladapted for a long time, and then rapidly shift into a relatively adapted state, in which persistence no longer depends upon recurrent immigration.
Full Text
The Full Text of this article is available as a PDF (549.4 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Gomulkiewicz R., Holt R. D., Barfield M. The effects of density dependence and immigration on local adaptation and niche evolution in a black-hole sink environment. Theor Popul Biol. 1999 Jun;55(3):283–296. doi: 10.1006/tpbi.1998.1405. [DOI] [PubMed] [Google Scholar]
- Kawecki T. J. Adaptation to marginal habitats: contrasting influence of the dispersal rate on the fate of alleles with small and large effects. Proc Biol Sci. 2000 Jul 7;267(1450):1315–1320. doi: 10.1098/rspb.2000.1144. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lande R. Expected time for random genetic drift of a population between stable phenotypic states. Proc Natl Acad Sci U S A. 1985 Nov;82(22):7641–7645. doi: 10.1073/pnas.82.22.7641. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ronce O., Kirkpatrick M. When sources become sinks: migrational meltdown in heterogeneous habitats. Evolution. 2001 Aug;55(8):1520–1531. doi: 10.1111/j.0014-3820.2001.tb00672.x. [DOI] [PubMed] [Google Scholar]
- Tufto J. Quantitative genetic models for the balance between migration and stabilizing selection. Genet Res. 2000 Dec;76(3):285–293. doi: 10.1017/s0016672300004742. [DOI] [PubMed] [Google Scholar]