Universität Bern
Eawag

Adaptive radiation

Ecology and genetics of adaptive radiation

The theory of speciation has often been polarized between the views that speciation is driven by external events that physically isolate populations, or by environmental pressures and ecological processes within populations. The geographical hypothesis dominated speciation theory for several decades. The ecological hypothesis, which originated in the early days of evolutionary theory, is experiencing a recent revival. The mechanisms associated with these alternative ideas have often been studied in isolation, except in the framework of reinforcement. A different form of interaction between ecological processes and external events is if genetic merging of populations by hybridization after periods of independent evolution generates populations with genetic properties that make them particularly prone to adaptive sympatric diversification in response to ecological pressures. Although speciation would be sympatric, driven by ecology, transient geographical isolation would generate the genetic variation that makes adaptive evolutionary responses to divergent selection possible.

On going projects

Building a molecular phylogeny

This project involves building a molecular phylogeny for many populations and ecotypes of coregonids from the Alpine region of Europe using AFLPs and mitochondrial DNA sequence variation and collection of morphological and ecological data for the same populations. The data will be used to reconstruct colonization and hybridization scenarios and test hypotheses for morphological and ecological adaptation.

Ecological resource profiles available for whitefish populations

This project involves quantification of ecological resource profiles available for whitefish populations in different lakes and experimental quantification of diet preference profiles to generate adaptive landscapes. These will be used to predict ecological and species diversity of whitefish. Simultaneously we quantify morphological and ecological diversity and gene flow between ecotypes within lakes, and compare these with predictions derived from the environment.