|Title / Titel||The evolutionary potential of small and isolated populations|
|Abstract (PDF, 14 KB)|
|Summary / Zusammenfassung||This project assesses the evolutionary significance of small and isolated populations. Specific questions include whether small populations have reduced levels of genetic variation, are more divergent from one another genetically, experience more marginal conditions and stronger selection than large populations, are more (or less) likely to be locally adapted, and suffer from inbreeding depression that overwhelms fitness advantages conferred by their unique adaptations.
The project focuses on the common frog, Rana temporaria, in which Swiss breeding aggregations vary over three orders of magnitude in isolation and population size. Preliminary data show that population size is correlated with habitat conditions, and that isolated populations have reduced neutral genetic variation. We are conducting field surveys of about 70 breeding sites to characterize relationships among population size, isolation, genetic variation, and local habitat and landscape features. The project includes outdoor mesocosm experiments to measure quantitative genetic variation in populations having different degrees of size and isolation. Field experiments are measuring how the natural selection varies among populations, and whether the extent of local adaptation varies with population size or isolation as predicted by theory. Crosses among populations will be used to compare fitness benefits due to local adaptation with fitness costs from inbreeding depression and genetic load, and to decide whether the balance between the two depends on population size.
Our study of genetic variation and adaptive divergence in Rana temporaria is relevant to the long-standing Fisher-Wright argument over the adaptive potential of small populations. It also addresses a parallel dispute that has developed within conservation biology over the relative magnitudes of genetic erosion, inbreeding depression, and existence of potentially unique genetic variation within small populations. Studies of natural selection and local adaptation are also important because they help predict the impact of environmental change on amphibians.
|Publications / Publikationen||Steiner, U. K., and J. Van Buskirk. 2008. Environmental stress and the costs of phenotypic plasticity. Journal of Evolutionary Biology 21:97-103.Van Buskirk, J. 2007. Body size variation, competitive interactions, and the local distribution of Triturus newts. Journal of Animal Ecology 76:559-567.Willi, Y., J. Van Buskirk, B. Schmid, and M. Fischer. 2007. Genetic isolation of fragmented populations is exacerbated by drift and selection. Journal of Evolutionary Biology 20:534-542.Willi, Y., J. Van Buskirk, and A. A. Hoffmann. 2006. Limits to the adaptive potential of small populations. Annual Review of Ecology, Evolution, and Systematics 37:433-458.Van Buskirk, J., and Y. Willi. 2006. The change in quantitative genetic variation under inbreeding. Evolution 60:2428-2434.Schmidt, B. R., N. Ramer, and J. Van Buskirk. 2006. A trophic polymorphism induced by both predators and prey. Evolutionary Ecology Research 8:1301-1309.Weitere Informationen|
|Keywords / Suchbegriffe||adaptation, amphibians, conservation biology, evolution, natural selection, population genetics|
|Project leadership and contacts /
Projektleitung und Kontakte
|Funding source(s) /
|SNF (Personen- und Projektförderung)
|Duration of Project / Projektdauer||Oct 2006 to Sep 2010|