Evolutionary consequences of interspecific hybridization: Daphnia resting egg banks as biological archives

• Applicant: Professor Dr. Klaus Schwenk
• Subject Area: Evolutionary Cell and Developmental Biology (Zoology)
• Term: from 2006 to 2007
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 27051794

Despite many studies on natural interspecific hybridization among plants and animals, few cover long enough time periods to describe the origin and fate of hybrid lineages or to associate levels of interspecific gene flow with environmental conditions. Here we propose to extend our population genetic studies of a Daphnia species complex using resting eggs isolated from sediments of Lake Constance and Lake Greifensee. Initially, only one species (D. hyalina) was found in both lakes (before 1950), later on D. galeata invaded both lakes which resulted subsequently in interspecific hybridization. Based on our preliminary data which provide evidence for a massive hybrid sweep in both populations, we aim to describe the consequences of hybridization (e.g. introgression) during the course of the 20th century (~100 years) using nuclear and mitochondrial DNA data. In addition, we will hatch individuals from several time periods (1960¿s, 1970¿s, 1990¿s and 2000¿s) and test for differential hatching and phenotypic variation over a time period of 40 years. This combined approach of population genetics and phenotypic analyses using resting eggs from lake sediments will allow us to measure the level of reproductive isolation, gene flow, and selection in a species complex during the past century.

• DFG Programme: Research Grants