Maintenance of genetic variation

Evolutionary change requires genetic variation, and genetic variation can only be maintained when there is not too much directional selection occurring. This is an evolutionary paradox not yet fully solved. As evolutionary ecologists interested in adaptation to global change, we are also interested in how genetic variation is maintained within natural populations. Plumage polymorphism is a good model to study this. We do so for plumage variation in pied flycatchers, that range from female crypsis to distinct male black and white plumage¹. Recently we also started to study colour polymorphism in common buzzards.

Colour polymorphisms are common in raptor species. Since these morphs have a heritable basis, an important biological question is how this variation is maintained over evolutionary time. Frequency-dependent selection pressures are expected, but few empirical examples from this exist in nature. Additionally, performance of morphs depends on habitat characteristics, and may vary over time. Little is known about potential long-term changes and spatial variation in morph frequencies, and how these relate to variation in fitness.

Past research has illuminated a heterozygous advantage in common buzzard colour polymorphism², but this may be population-specific, and fails to explain spatial variation in the distribution of morph types. In this project we aim at describing patterns of spatial and temporal variation in the colour morphs of the common buzzard, and its potential fitness consequences. For long-term temporal trends in morph frequencies and for morph-dependent fitness consequences two datasets from the Netherlands are available collected by dedicated volunteers (Christiaan de Vries and Rob Bijlsma). The spatial variation in morphs will be investigated at different spatial scales using a variety of approaches:

1. Detailed year-round observations in several habitats in Northern Germany,
2. compiling existing data from museums and local bird organizations,
3. building up a citizen science network to let birders collect data from a large part of Europe.

PhD student:

• Elena Kappers

Collaboration:

• Bart Kempenaers, Max Planck Institute of Ornithology

References:

1. Lehtonen PK et al (2012), Heredity 108:431-440, doi:10.1038/hdy.2011.93
2. Kruger O et al (2001), Evolution 55:1207–1214, doi:10.1111/j.0014-3820.2001.tb00640.x