Evidence for morphological and adaptive genetic divergence between lake and stream habitats in European minnows (Phoxinus phoxinus, Cyprinidae)

Abstract

Natural selection drives local adaptation, potentially even at small temporal and spatial scales. As a result, adaptive genetic and phenotypic divergence can occur among populations living in different habitats. We investigated patterns of differentiation between contrasting lake and stream habitats in the cyprinid fish European minnow (Phoxinus phoxinus) at both the morphological and genomic levels using geometric morphometrics and AFLP markers, respectively. We also used a spatial correlative approach to identify AFLP loci associated with environmental variables representing potential selective forces responsible for adaptation to divergent habitats. Our results identified different morphologies between lakes and streams, with lake fish presenting a deeper body and caudal peduncle compared to stream fish. Body shape variation conformed to a priori predictions concerning biomechanics and swimming performance in lakes vs. streams. Moreover, morphological differentiation was found to be associated with several environmental variables, which could impose selection on body and caudal peduncle shape. We found adaptive genetic divergence between these contrasting habitats in the form of 'outlier' loci (2.9%) whose genetic divergence exceeded neutral expectations. We also detected additional loci (6.6%) not associated with habitat type (lake vs. stream), but contributing to genetic divergence between populations. Specific environmental variables related to trophic dynamics, landscape topography and geography were associated with several neutral and outlier loci. These results provide new insights into the morphological divergence and genetic basis of adaptation to differentiated habitats.

Shape variation in the least killifish: ecological associations of phenotypic variation and the effects of a common garden

“…This is particularly true for the body morphology of fish, which has a direct effect on locomotion and, ultimately, fitness (Collin and Fumagalli 2011; Fu et al. 2013).…”

“…This paradigm is particularly true for fish, whose shape in a fluid medium is influenced by many factors, including predation pressure, population density, habitat complexity, water chemistry, and flow rate (Walker and Bell 2000; Hendry et al. 2006; Gomes and Monteiro 2008; Collin and Fumagalli 2011; Ruehl et al. 2011; Young et al.…”

Distribution of Eurasian minnows (Phoxinus: Cypriniformes) in the Western Balkans

“…Morphology of Phoxinus is very affected by habitat type and intraspecies differences in body shape that can be large as those observed on interspecific level. Intraspecific morphological differences can be linked to different swimming modes and foraging in distinct habitats such as lakes and streams Collin and Fumagalli, 2011).…”

Intraspecific Morphological Variation in Two Common Marine Fish Species from South Africa

“…Many fishes exhibit sexual dimorphism [3,4]. In addition, intraspecific morphological variation has been observed in a variety of fish species associated with variation in habitat, diet, and other factors [5][6][7][8][9][10]. In many cases this variation has been shown to be heritable.…”