Project description

Hybrid zones are narrows regions in which genetically distinct populations meet, mate and produce hybrid offspring. They provide excellent opportunities to study the mechanisms behind speciation.

Some examples of questions that can be studied in hybrid zones are

1) How do they arise?

2) One common feature of many hybrid zones is that they remain stable over long periods of time, but which factors create this stability and what decides the position of a zone? One theory, the tension zone model, states that the width of a cline is decided by selection against hybrids and dispersal into the zone by individuals from its outside.

3) Under which circumstances will the gene flow between hybridizing populations decrease to such an extent that they get isolated from each other? If such isolation leads to the formation of new species this is called parapatric speciation, a field that includes controversial topics such as reinforcement and character displacement.

As a model system for empirical studies we use the hybrid zone between the carrion crow Corvus corone corone and the hooded crow C. c. cornix in southern Denmark and northern Germany. In this project we are investigating both with empirical as well as theoretical methods.

Anders Brodin, Fredrik Haas, Bengt Hansson

Related publications

Brodin A. and Haas F. 2009. Hybrid zone maintenance by non-adaptive mate choice. - Evolutionary Ecology. 23: 17-29. doi:10.1007/s10682-007-9173-9

Brodin, A. & Haas, F. 2006. Speciation by perception. - Animal Behaviour 72:139-146. doi:10.1016/j.anbehav.2005.10.011 (pdf)

Haas, F. & Brodin, A. 2005. The Crow Corvus corone hybrid zone in southern Denmark and northern Germany. - Ibis 147: 649-656. (pdf)

Haas, F., Pointer, M. A., Saino, N., Brodin, A., Mundy, N. I. & Hansson, B. 2009. An analysis of population genetic differentiation and genotype - phenotype association across the hybrid zone of carrion and hooded crows using microsatellites and MC1R. - Molecular Ecology 18: 294-305. doi: 10.1111/j.1365-294X.2008.04017.x