Habitat Discontinuities Separate Genetically Divergent Populations of a Rocky Shore Marine Fish.

Enrique Blanco Gonzalez,Halvor Knutsen,Per Erik Jorde,Tzen-Yuh Chiang

doi:10.1371/journal.pone.0163052

Enrique Blanco Gonzalez, Halvor Knutsen + Show 2 more

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https://doi.org/10.1371/journal.pone.0163052

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Abstract

Habitat fragmentation has been suggested to be responsible for major genetic differentiations in a range of marine organisms. In this study, we combined genetic data and environmental information to unravel the relative role of geography and habitat heterogeneity on patterns of genetic population structure of corkwing wrasse (Symphodus melops), a rocky shore species at the northern limit of its distribution range in Scandinavia. Our results revealed a major genetic break separating populations inhabiting the western and southern coasts of Norway. This genetic break coincides with the longest stretch of sand in the whole study area, suggesting habitat fragmentation as a major driver of genetic differentiation of this obligate rocky shore benthic fish in Scandinavia. The complex fjords systems extending along the western coast of Norway appeared responsible for further regional genetic structuring. Our findings indicate that habitat discontinuities may lead to significant genetic fragmentation over short geographical distances, even for marine species with a pelagic larval phase, as for this rocky shore fish.

Highlights

Connectivity between geographically separated populations plays a pivotal role in populations dynamics and genetic diversity [1]
The current study performed on corkwing wrasse collected along the Norwegian coast revealed the existence of a major genetic discontinuity or “break” in this rocky shore fish species
The genetic break was located in the south-western part of the Scandinavian Peninsula, separating populations inhabiting the western and southern (i.e., Skagerrak) coast of the Scandinavian Peninsula (FST = 0.107, P < 0.001, Table 3)

Summary

Introduction

Connectivity between geographically separated populations plays a pivotal role in populations dynamics and genetic diversity [1]. The presence of physical barriers [2], environmental clines [3] and anthropogenic disturbances [4] may prevent connectivity, while the lack of suitable conditions to satisfy the biological requirements of the species [5,6] will shape patterns of genetic structure. The relatively large population sizes and high dispersal potential of marine organisms commonly result in lower intraspecific genetic differentiation compared to freshwater species [7]. Biological attributes of species, such as dispersal ability and reproductive mode, play an important role on population demography, connectivity and the location of genetic Some species display sharp genetic discontinuities or breaks due to a variety of historical and contemporary processes acting as barriers to dispersal and gene flow, such as patchiness of suitable habitat or discontinuities in the oceanographic regimes [8,9,10].

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