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Genetic and phenotypic population divergence on a microgeographic scale in brown trout
Author(s) -
STELKENS RIKE B.,
JAFFUEL GEOFFREY,
ESCHER MATTHIAS,
WEDEKIND CLAUS
Publication year - 2012
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/j.1365-294x.2012.05581.x
Subject(s) - biology , brown trout , salmo , trout , ecology , population , genetic divergence , population fragmentation , genetic diversity , isolation by distance , habitat , local adaptation , habitat fragmentation , genetic variation , genetic structure , gene flow , fishery , genetics , demography , sociology , fish <actinopterygii> , gene
Salmonid populations of many rivers are rapidly declining. One possible explanation is that habitat fragmentation increases genetic drift and reduces the populations’ potential to adapt to changing environmental conditions. We measured the genetic and eco‐morphological diversity of brown trout ( Salmo trutta) in a Swiss stream system, using multivariate statistics and Bayesian clustering. We found large genetic and phenotypic variation within only 40 km of stream length. Eighty‐eight percent of all pairwise F ST comparisons and 50% of the population comparisons in body shape were significant. High success rates of population assignment tests confirmed the distinctiveness of populations in both genotype and phenotype. Spatial analysis revealed that divergence increased with waterway distance, the number of weirs, and stretches of poor habitat between sampling locations, but effects of isolation‐by‐distance and habitat fragmentation could not be fully disentangled. Stocking intensity varied between streams but did not appear to erode genetic diversity within populations. A lack of association between phenotypic and genetic divergence points to a role of local adaptation or phenotypically plastic responses to habitat heterogeneity. Indeed, body shape could be largely explained by topographic stream slope, and variation in overall phenotype matched the flow regimes of the respective habitats.