Part D
Intraspecific genetic diversity along plant species diversity gradients

Relationships between diversity among species and genetic diversity within species are only poorly understood. Levels and patterns of genetic diversity within a population are the result of historical processes, part of them being adaptive. Thus, it is far from being obvious that today’s species diversity of an ecosystem has a direct impact on the genetic diversity of its keystone species or vice versa. However, simulations of the interacting effects of immigration rate (gene flow) and environmental heterogeneity on the correlated diversity of genes and species led to positive and sometimes strong correlations.
Recent studies have shown that plant species diversity and genetic diversity in keystone species may have significant effects on the diversity of associated herbivores and ecosystem processes.
We want to test the hypotheses that levels of genetic diversity (adaptive and neutral) within populations of keystone species and tree species diversity are correlated and that the genetic diversity in keystone tree species has an effect on the diversity of associated organisms (e.g. microbes, phytophagous insects) in temperate and tropical forest ecosystems.

Part D1

Reiner Finkeldey, Oliver Gailing

Intraspecific genetic diversity of keystone species along gradients of plant species diversity in temperate and tropical forests

Our focus will be on keystone species in temperate and tropical forest ecosystems with specific, comparable life-history traits, i.e. Fagus sylvatica and Shorea leprosula.
We will study levels of genetic diversity at anonymous markers (AFLPs), putatively neutral microsatellites, and at selected genes (partial sequences) for both species along a gradient of (tree) species diversity.
In a first experiment the extreme populations of the gradient (total: at least five populations) will be investigated for each species. Each population pair consists of one population occuring in high abundance and size (“dominating” in an ecosystem with low species diversity) and the other occuring in low density and/or population size (“rare” in an ecosystem with high species diversity). Intermediate populations will be analysed in order to observe a gradient of increasing species diversity. The populations from a single pair or gradient will be selected to be reproductively isolated from each other. Furthermore, we will analyse whether genetic diversity within a population of foundation species and species diversity are positively correlated with species diversity in the dependent community.