title: Individual differences in migratory behavior shape population genetic structure and microhabitat choice in sympatric blackcaps (Sylvia atricapilla).
abstract: In migratory birds, traits such as orientation and distance are known to have a strong genetic background, and they often exhibit considerable within-population variation. How this variation relates to evolutionary responses to ongoing selection is unknown because the underlying mechanisms that translate environmental changes into population genetic changes are unclear. We show that within-population genetic structure in southern German blackcaps (Sylvia atricapilla) is related to individual differences in migratory behavior. Our 3-year study revealed a positive correlation between individual migratory origins, denoted via isotope (δ (2)H) values, and genetic distances. Genetic diversity and admixture differed not only across a recently established migratory polymorphism with NW- and SW-migrating birds but also across δ (2)H clusters within the same migratory route. Our results suggest assortment based on individual migratory origins which would facilitate evolutionary responses. We scrutinized arrival times and microhabitat choice as potential mechanisms mediating between individual variation in migratory behavior and assortment. We found significant support that microhabitat choice, rather than timing of arrival, is associated with individual variation in migratory origins. Moreover, examining genetic diversity across the migratory divide, we found migrants following the NW route to be genetically more distinct from each other compared with migrants following the traditional SW route. Our study suggests that migratory behavior shapes population genetic structure in blackcaps not only across the migratory divide but also on an individual level independent of the divide. Thus, within-population variation in migratory behavior might play an important role in translating environmental change into genetic change.
authors: Redpath Museum and Department of Biology, McGill University 859 Sherbrooke St. W., Montreal, Quebec, H3A 0C4, Canada ; Faculty of Biology, Department of Evolutionary Biology and Animal Ecology, University of Freiburg Hauptstrasse 1a, 79104, Freiburg, Germany.
authors: Gregor
authors: G
authors: Rolshausen
authors: Gernot
authors: G
authors: Segelbacher
authors: Claudia
authors: C
authors: Hermes
authors: Keith A
authors: KA
authors: Hobson
authors: H Martin
authors: HM
authors: Schaefer
keywords: Blackcap; bottleneck; micro-evolution; microhabitat choice; migratory connectivity; migratory divide; spatial isolation; stable isotopes