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Open Access Research article

Testing for local adaptation in brown trout using reciprocal transplants

Rike B Stelkens12*, Manuel Pompini1 and Claus Wedekind1

Author affiliations

1 Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, CH-1015, Switzerland

2 Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK

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Citation and License

BMC Evolutionary Biology 2012, 12:247  doi:10.1186/1471-2148-12-247

Published: 18 December 2012

Abstract

Background

Local adaptation can drive the divergence of populations but identification of the traits under selection remains a major challenge in evolutionary biology. Reciprocal transplant experiments are ideal tests of local adaptation, yet rarely used for higher vertebrates because of the mobility and potential invasiveness of non-native organisms. Here, we reciprocally transplanted 2500 brown trout (Salmo trutta) embryos from five populations to investigate local adaptation in early life history traits. Embryos were bred in a full-factorial design and raised in natural riverbeds until emergence. Customized egg capsules were used to simulate the natural redd environment and allowed tracking the fate of every individual until retrieval. We predicted that 1) within sites, native populations would outperform non-natives, and 2) across sites, populations would show higher performance at ‘home’ compared to ‘away’ sites.

Results

There was no evidence for local adaptation but we found large differences in survival and hatching rates between sites, indicative of considerable variation in habitat quality. Survival was generally high across all populations (55% ± 3%), but ranged from 4% to 89% between sites. Average hatching rate was 25% ± 3% across populations ranging from 0% to 62% between sites.

Conclusion

This study provides rare empirical data on variation in early life history traits in a population network of a salmonid, and large-scale breeding and transplantation experiments like ours provide powerful tests for local adaptation. Despite the recently reported genetic and morphological differences between the populations in our study area, local adaptation at the embryo level is small, non-existent, or confined to ecological conditions that our experiment could not capture.

Keywords:
Local adaptation; Reciprocal transplants; Salmo trutta