Limited population genetic variation but pronounced seascape genetic structuring in populations of the Mediterranean mussel (Mytilus galloprovincialis) from the eastern Adriatic Sea

Joanna S Hamilton; Marina Piria; Ana Gavrilović; Mirna Mrkonjić Fuka; Lidija Svečnjak; Slađana Nikolić; Rigers Bakiu; Jonathan P A Gardner

doi:10.1002/ece3.9729

Limited population genetic variation but pronounced seascape genetic structuring in populations of the Mediterranean mussel (Mytilus galloprovincialis) from the eastern Adriatic Sea

Ecol Evol. 2023 Jan 24;13(1):e9729. doi: 10.1002/ece3.9729. eCollection 2023 Jan.

Authors

Joanna S Hamilton¹, Marina Piria^{2

3}, Ana Gavrilović², Mirna Mrkonjić Fuka⁴, Lidija Svečnjak², Slađana Nikolić⁵, Rigers Bakiu^{6

7}, Jonathan P A Gardner¹

Affiliations

¹ School of Biological Sciences Victoria University of Wellington Wellington New Zealand.
² Department of Fisheries, Apiculture, Faculty of Agriculture, Wildlife Management and Special Zoology University of Zagreb Zagreb Croatia.
³ Department of Ecology and Vertebrate Zoology, Faculty of Biology and Environmental Protection University of Łódź Łódź Poland.
⁴ Department of Microbiology, Faculty of Agriculture University of Zagreb Zagreb Croatia.
⁵ Institute of Marine Biology University of Montenegro Kotor Montenegro.
⁶ Department of Aquaculture and Fisheries, Faculty of Agriculture and Environment Agricultural University of Tirana Tirana Albania.
⁷ Albanian Center for Environmental Protection and Sustainable Development Tirana Albania.

Abstract

Population genetic analysis of variation at five neutral microsatellite loci for Mediterranean mussels (Mytilus galloprovincialis) from 18 sites along the eastern Adriatic Sea revealed little or no spatial variation. In contrast, seascape genetics analysis revealed a pronounced locus-specific gradient in allelic and genotypic frequencies across the study region. At a sixth locus, MGE7, the frequencies of two alleles, MGE7²⁴³ and MGE7²⁴⁹, were strongly associated, negatively and positively, respectively, with a single environmental variable - minimum salinity (minSAL). The frequency of the MGE7^243/243 homozygous genotype was strongly negatively associated with minSAL, whereas the frequencies of the MGE7^246/249 and the MGE7^249/249 genotypes were strongly positively correlated with minSAL. Interpretation of these pronounced gradients is confounded by the fact that minSAL and another environmental variable, maximum sea surface temperature (maxSST), are highly correlated (R = -.911) and are therefore not necessarily acting independently. BLAST searches of the MGE7 locus against M. galloprovincialis whole genome shotgun sequence returned an alignment with contig mg10_S01094 (accession UYJE01010330.1) and 7 predicted M. galloprovincialis proteins VDI82194.1 - VDI82200.1. Conserved domain searches revealed a similar structure to the transcriptional regulator Msx2-interacting protein. The BLASTp search also returned significant alignments to Msx2-interacting proteins in Mytilus coruscus, Crassostrea virginica, and Haliotis rubra. The existence of the MGE7 gradient highlights the role that environmental variation may play in retarding gene flow among wild M. galloprovincialis populations, and also how the success of collection of young mussels (spat) from one site and their transfer to another site (the farm) may be influenced by a single factor such as minSAL or maxSST on a localized scale.

Keywords: Mediterranean Sea; Mollusca, Bivalvia; aquaculture; environmental variation; gene flow; genetic cline; selection.

Associated data

Dryad/10.5061/dryad.p8cz8w9t8