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Genetic differences on a local scale.

Kim van der Linde , Paul M. Brakefield , Jan G. Sevenster, Jacques J. M. van Alphen & Bas J. Zwaan

Presentation given at the IX-th congress of the European Society for Evolutionary Biology , Leeds, United Kingdom.
(Powerpoint presentation )

Abstract
The impact of human activity on the natural environment is visible almost everywhere. Sometimes, these differences are clear and the negative impact for the biodiversity is evident. After a clear-cut of the rainforest, only some well-adapted pioneer species can survive. For that reason, less invasive logging methods have been developed. Recent studies have showed that sometimes species diversity could even increase in such areas as forest-edge species establish themselves in the selectively logged areas. However, a simultaneous loss of genetic diversity could still occur as the invading population has to adapt to the changed environment, and genetic variation have been reduced because the population went through a bottleneck. Changes in genetic variation could occur even when the new environment is within the normal range of habitats occupied by a species. Habitat related adaptation in life-history traits in Drosophila is almost exclusively studied in the laboratory often with flies collected over latitudinal clines, sometimes as long as a whole continent. The impact of habitat changes on populations on relative short distance of a few kilometres is rarely studied, and field studies are even rarer. In 1998, we carried out two field experiments in Panama to measure habitat-related differences in three life-history traits: development time, starvation resistance, and body size. We established two short transects of a few kilometres with each three habitats: closed canopy forest, grassland with scrub patches and an intermediate transition zone. This range in habitats is naturally occupied by most species in our study. The results show that populations, from adjacent collection sites but from different habitats, differ genetically and that different species follow the same pattern. The consequences of these results for the management of genetic diversity will be discussed.