Abstract
Interactions between environmental factors and complex life‐history characteristics of marine organisms produce the genetic diversity and structure observed within species. Our main goal was to test for genetic differentiation among eastern oyster populations from the coastal region of Canadian Maritimes against expected genetic homogeneity caused by historical events, taking into account spatial and environmental (temperature, salinity, turbidity) variation. This was achieved by genotyping 486 individuals originating from 13 locations using RADSeq. A total of 11,321 filtered SNPs were used in a combination of population genomics and environmental association analyses. We revealed significant neutral genetic differentiation (mean F ST = 0.009) between sampling locations, and the occurrence of six major genetic clusters within the studied system. Redundancy analyses (RDAs) revealed that spatial and environmental variables explained 3.1% and 4.9% of the neutral genetic variation and 38.6% and 12.2% of the putatively adaptive genetic variation, respectively. These results indicate that these environmental factors play a role in the distribution of both neutral and putatively adaptive genetic diversity in the system. Moreover, polygenic selection was suggested by genotype–environment association analysis and significant correlations between additive polygenic scores and temperature and salinity. We discuss our results in the context of their conservation and management implications for the eastern oyster.
Highlights
The population genetic structure of organisms is influenced by com‐ plex interactions between evolutionary forces, life‐history charac‐ teristics and environmental conditions
Six genetic clusters were identified based on the lowest Bayesian information criterion (BIC) value (Supporting Information Figure S5), though results associated with K values between 8 and 10 seemed more plausible according to the spatial distribution of sampling sites (Figure 2; Supporting Information Figure S6)
Despite its economic and ecological importance, we know relatively little about levels of genetic structure and diversity in the eastern oyster
Summary
The population genetic structure of organisms is influenced by com‐ plex interactions between evolutionary forces, life‐history charac‐ teristics and environmental conditions. Advances in genomic tools, with sufficient resolution to study population genetic processes in marine systems, have resulted in considerable interest in the fast‐growing field of marine and seascape genomics (Gagnaire & Gaggiotti, 2016; Selkoe et al, 2016) and the ability for genomics to enhance manage‐ ment of marine resources (Bernatchez et al, 2017) These studies have improved our understanding of how genomic variation in ma‐ rine and coastal ecosystems is spatially distributed, and how these patterns are influenced by environmental conditions (Benestan et al, 2015; DiBattista et al, 2017; Diopere et al, 2017; Lal, Southgate, Jerry, Bosserelle, & Zenger, 2017; Metivier, Kim, & Addison, 2017; Sandoval‐Castillo, Robinson, Hart, Strain, & Beheregaray, 2018; Van Wyngaarden et al, 2018; Xuereb, Benestan, et al, 2018; Xuereb, Kimber, Curtis, Bernatchez, & Fortin, 2018). While marine species are typically characterized by low absolute levels of genetic differ‐ entiation relative to their terrestrial counterparts, these studies have revealed complex interactions between spatial and environmental processes, mediated by a species’ particular life‐history traits, oper‐ ating at a different scale than in familiar terrestrial systems
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
