Population genetic structure and differential selection in musselMytilus chilensis

Abstract

This study examines the genetic connectivity between natural banks of Chilean mussel, Mytilus chilensis, located in Reloncav ı Fjord. This sector is the principal source of seed for commercial farming and has the second-largest aquaculture production volume in the country. The objects of this work are as follows: (1) to estimate the degree of connectivity between patches (microscale) located in the intertidal/subtidal zones, evaluating the presence of selection processes; and (2) to identify connectivity patterns by gene flow between subpopulations (mesoscale) in order to determine whether they all correspond to a common population (metapopulation). We analysed individuals distributed in the intertidal and subtidal zones of five locations by sequencing the mitochondrial cytochrome oxidase I gene and eight nuclear DNA microsatellite loci. Comparison of the two tidal zones presented differences revealed by the COI gene. The locations presented low genetic differentiation; however, differences were found in both markers at the mouth of the fjord.The differences between the tidal zones may result from differentiated natural selection processes between the intertidal and subtidal environments, with those in the intertidal subjected to greater selective pressure. There is effective connectivity between the locations, facilitated by the capacity for dispersion of the larvae and certain oceanographic processes, which would also explain the differences observed in the location at the mouth of the fjord. Because these banks sustain mussel aquaculture activity throughout the country, it is important to take measures to ensure their proper maintenance, observing all the indicators including their genetic diversity and structure.

Adaptive Differences in Gene Expression in Farm-Impacted Seedbeds of the Native Blue Mussel Mytilus chilensis

“…Studies with neutral nuclear markers (microsatellites) report low genetic differentiation (F ST = 0.042) among wild mussel's samples distributed along a latitudinal gradient of temperature, salinity, and oxygen availability; including some farm-impacting seedbeds (Larraín et al, 2012(Larraín et al, , 2015Araneda et al, 2016;Astorga et al, 2018Astorga et al, , 2020. The use of adaptive Single Nucleotide Polymorphic markers (outlier SNPs in the DNA), obtained by RAD-Seq suggests that mussel populations may retain local adaptations (Araneda et al, 2016).…”

The Mediterranean Mussel Mytilus galloprovincialis (Mollusca: Bivalvia) in Chile: Distribution and Genetic Structure of a Recently Introduced Invasive Marine Species

“…However, this native species exhibited very low genetic differentiation amongst the natural beds sampled along its whole distribution range. In other studies, a low genetic differentiation between natural beds of Chilean mussels was also reported (e.g., [ 106 , 107 , 108 , 109 ]). This may be due to the aquaculture of this mussel that involves the transfer of juveniles (seeds) from collection areas to the growth centres located in bays and fjords with high primary production [ 110 ].…”

Chromosome-Level Genome Assembly of the Blue Mussel Mytilus chilensis Reveals Molecular Signatures Facing the Marine Environment

“…As a gonochoric species with an annual gametogenic cycle, sexual maturity occurs in spring–summer, where planktonic larvae can drift between 20 and 45 days before settlement [ 42 ]. Dispersal potential has been estimated to be up to 30 km, allowing different degrees of gene flow among mussel populations [ 43 ].…”