The role of hybridization in the colonization of newly opened habitats

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Hybridization between species is a creative evolutionary force that forms novel genotypes and allows rapid adaptation to new environments. We propose to study how hybrid-specific traits may facilitate the colonization of novel habitats, using the Daphnia hybrid complex as a model system. We will screen Daphnia communities in ten small quarry lakes which have been created and thus opened for colonization only about 20 years ago. In addition, in contrast to larger lakes, these shallow and unstable habitats are “re-opened” for colonization every spring: Daphnia survive winter only exceptionally as clonal lineages. Instead, they need to be re-established from sexually produced diapausing eggs. Communities will be screened at 15 microsatellite loci and three contrasting scenarios of hybrid maintenance will be tested: survival of hybrids as clonal lineages, recurrent hybridization events or establishment of hybrids through migrants. In addition, using laboratory experiments we will test the hypothesis that hybrids have more diverse phenotypes compared to parental taxa (due to increased genetic variation in hybrid individuals). Finally, the field and laboratory data will be used for parameterization of a mathematical model, which will be developed to study the contribution of different ecological parameters to the success of hybrids. The proposed combination of empirical and theoretical approaches will advance our understanding of the role of hybridization in the colonization of new habitats and, more generally, of genetic exchange in adaptive evolution.