Genetic biodiversity in the Baltic Sea: species-specific patterns challenge management

Lovisa Wennerström,Daniel Johansson,Roman Wenne,Anti Vasemägi,Kerstin Johannesson,Juha Merilä,Carl André,Fred M Utter,Craig R Primmer,Nils Ryman,Małgorzata Zbawicka,Ricardo Pereyra,Annica Sandström,Lena Kautsky,Linda Laikre,Jacquelin Defaveri,Natalia Mikhailova,Amber G F Teacher,Nurul Izza Ab Ghani

doi:10.1007/s10531-013-0570-9

Abstract

Information on spatial and temporal patterns of genetic diversity is a prerequisite to understanding the demography of populations, and is fundamental to successful management and conservation of species. In the sea, it has been observed that oceanographic and other physical forces can constitute barriers to gene flow that may result in similar population genetic structures in different species. Such similarities among species would greatly simplify management of genetic biodiversity. Here, we tested for shared genetic patterns in a complex marine area, the Baltic Sea. We assessed spatial patterns of intraspecific genetic diversity and differentiation in seven ecologically important species of the Baltic ecosystem—Atlantic herring (Clupea harengus), northern pike (Esox lucius), European whitefish (Coregonus lavaretus), three-spined stickleback (Gasterosteus aculeatus), nine-spined stickleback (Pungitius pungitius), blue mussel (Mytilus spp.), and bladderwrack (Fucus vesiculosus). We used nuclear genetic data of putatively neutral microsatellite and SNP loci from samples collected from seven regions throughout the Baltic Sea, and reference samples from North Atlantic areas. Overall, patterns of genetic diversity and differentiation among sampling regions were unique for each species, although all six species with Atlantic samples indicated strong resistence to Atlantic-Baltic gene-flow. Major genetic barriers were not shared among species within the Baltic Sea; most species show genetic heterogeneity, but significant isolation by distance was only detected in pike and whitefish. These species-specific patterns of genetic structure preclude generalizations and emphasize the need to undertake genetic surveys for species separately, and to design management plans taking into consideration the specific structures of each species.

Highlights

Genetic variation is a prerequisite for species to adapt to a changing environment (Redford and Richter 1997; Reusch et al 2005)
All species except the Atlantic herring exhibit significant allele frequency differences among sampling regions within the Baltic Sea, for three-spined stickleback only one pairwise FST value remained significant after Bonferroni correction (Table 2; Pairwise FST values between all samples for each species are found in Tables S2 a–g)
Among the originally marine species we find few shared patterns, except for the common genetic barrier reported by the software BARRIER that separates Baltic samples from Atlantic ones and the lack of major genetic barriers supported by significant FST values within the Baltic Sea for herring and three-spined stickleback

Summary

Introduction

Genetic variation is a prerequisite for species to adapt to a changing environment (Redford and Richter 1997; Reusch et al 2005). The importance of conserving genetic biodiversity is recognized both scientifically Identifying population genetic structures of species, describing the distribution of genetic diversity, and understanding the causes for these structures are important for effective management and conservation (Laikre et al 2005a, 2008; Schmitt 2007). As all ecosystems contain large numbers of species, multi-species population genetic studies have been suggested as a useful first step in genetic surveys of separate geographic areas (Kelly and Palumbi 2010; Sivasundar and Palumbi 2010).

Results

Discussion

Conclusion