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Population differentiation between natural and human-managed areas

Landscape change induced by humans can alter the environmental conditions and thus promote unusually rapid evolutionary changes and/or at remarkably small spatial scales. In a managed property and a natural reserve situated less than 10 km apart, we tested for morphological differentiation of a migratory insectivorous bird, the red-necked nightjar (Caprimulgus ruficollis). At both sites, we also estimated site fidelity and quantified the potential foraging opportunities for nightjars, as measured by food supply and the availability of foraging sites. Breeding birds in the managed habitat were significantly larger in skeletal size than those in the natural one. However, there were no significant differences in wing or tail length. No individual (out of 1130 captures overall over 5 years) exchanged areas between years and immigration from neighboring areas was almost negligible, suggesting strong site fidelity. Food supply for nightjars was similar in both areas, but the availability of foraging sites was remarkably higher in the managed property as a result of human activity. Hence, nightjars in the latter habitat benefited from increased foraging opportunities in relation to those in the natural site. It seems likely that the fine-scale variation in nightjar morphology reflects a phenotypic response to unequal local conditions, since non-random dispersal or differential mortality had been determined not to be influential. High site fidelity appears to contribute to the maintenance of body-size differences between the two habitats. Results from this nightjar population highlight the potential of human-induced changes in landscape configuration to promote population-level responses at exceedingly small geographic scales. información[at]ebd.csic.es Camacho et al (2015) The road to opportunities: Landscape change promotes body size divergence in a highly mobile species Curr Zool 62:00?00 


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