“Recovery is not just about fish moving from regions where they are more abundant. It’s also about whether the right fish are surviving and reproducing in the right places,” he says.

“If some populations carry locally useful traits, losing them could reduce the system’s ability to bounce back. This matters for local and regional fisheries of snapper and for re-stocking activities via aquaculture.”

link to open access paper…

https://onlinelibrary.wiley.com/doi/full/10.1111/mec.70273

Along the southern Australian coast, our findings reveal that broad environmental gradients in fluence patterns of dispersal and local adaptation in snapper, despite substantial gene flow among populations. We identified two distinct regional populations with minimal genetic differentiation at neutral loci among sites within each region, consistent with high demographic connectivity. However, genotype-environment association analyses identified 855 candidate adaptive loci linked to five key environmental variables that shape snapper ecology.

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This decoupling of demographic and adaptive connectivity highlights that substantial gene flow does not preclude local adaptation, with specific environmental stressors contributing to adaptive genetic divergence of local snapper populations.

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Local adaptation across environmental gradients despite high gene flow has been documented in numerous marine species, including Atlantic cod (Gadus morhua), Pacific herring (Clupea harengus) and sardines (Sardinops sagax) (Bradbury et al.2010;Limborg et al.2012; Teske et al. 2021). These studies suggest that the balance between selection and gene flow in marine environments may be more nuanced than often assumed.