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Synopsis The presence of standing genetic variation will play a role in determining a population's capacity to adapt to environmentally relevant stressors. In the Gulf of Mexico, extreme climatic events and anthropogenic changes to local hydrology will expose productive oyster breeding grounds to stressful low salinity conditions. We identified genetic variation for performance under low salinity (due to the combined effects of low salinity and genetic load) using a single-generation selection experiment on larvae from two populations of the eastern oyster, Crassostrea virginica. We used pool-sequencing to test for allele frequency differences at 152 salinity-associated genes for larval families pre- and post-low salinity exposure. Our results have implications for how evolutionary change occurs during early life history stages at environmentally relevant salinities. Consistent with observations of high genetic load observed in oysters, we demonstrate evidence for purging of deleterious alleles at the larval stage in C. virginica. In addition, we observe increases in allele frequencies at multiple loci, suggesting that natural selection for low salinity performance at the larval stage can act as a filter for genotypes found in adult populations. 

Salinity conditions in oyster breeding grounds in the Gulf of Mexico are expected to drastically change due to increased precipitation from climate change and anthropogenic changes to local hydrology. We determined the capacity of the eastern oyster, Crassostrea virginica , to adapt via standing genetic variation or acclimate through transgenerational plasticity (TGP). We outplanted oysters to either a low- or medium-salinity site in Louisiana for 2 years. We then crossed adult parents using a North Carolina II breeding design, and measured body size and survival of larvae 5 dpf raised under low or ambient salinity. We found that TGP is unlikely to significantly contribute to low-salinity tolerance since we did not observe increased growth or survival in offspring reared in low salinity when their parents were also acclimated at a low-salinity site. However, we detected genetic variation for body size, with an estimated heritability of 0.68 ± 0.25 (95% CI). This suggests there is ample genetic variation for this trait to evolve, and that evolutionary adaptation is a possible mechanism through which oysters will persist with future declines in salinity. The results of this experiment provide valuable insights into successfully breeding low-salinity tolerance in this commercially important species. 

Genomic methods are becoming increasingly valuable and established in ecological research, particularly in nonmodel species. Supporting their progress and adoption requires investment in resources that promote (i) reproducibility of genomic analyses, (ii) accessibility of learning tools and (iii) keeping pace with rapidly developing methods and principles.

We introduce marineomics.io, an open‐source, living document to disseminate tutorials, reproducibility tools and best principles for ecological genomic research in marine and nonmodel systems.

The website's existing content spans population and functional genomics, including current recommendations for whole‐genome sequencing, RAD‐seq, Pool‐seq and RNA‐seq. With the goal to facilitate the development of new, similar resources, we describe our process for aggregating and synthesizing methodological principles from the ecological genomics community to inform website content. We also detail steps for authorship and submission of new website content, as well as protocols for providing feedback and topic requests from the community.

These web resources were constructed with guidance for doing rigorous, reproducible science. Collaboration and contributions to the website are encouraged from scientists of all skill sets and levels of expertise.

 

A widespread adaptive change in antiherbivore response is seen in a common plant species in urban environments across 160 cities.