Taking the chaos out of genetic patchiness: seascape genetics reveals ecological and oceanographic drivers of genetic patterns in three temperate reef species

TLDR

Marine species often exhibit weak or complex genetic structuring that is dismissed as chaotic patchiness and deemed ecologically uninformative. This study shows that integrating data across three species and adding environmental variables can markedly enhance the predictive power of marine population genetics at fine spatial scales. The authors used kelp bed size, sea surface temperature, and model‑derived migration probabilities as predictors in linear and mixed‑effects models of genetic diversity and differentiation, selecting the best models with information‑theoretic criteria. They found significant interspecies correlations in microsatellite patterns, with kelp abundance as the strongest predictor and ocean circulation a secondary factor, indicating that shared environmental drivers can inform a unified marine management strategy and that such data clarify weak genetic signals.

Abstract

Abstract Marine species frequently show weak and/or complex genetic structuring that is commonly dismissed as ‘chaotic’ genetic patchiness and ecologically uninformative. Here, using three datasets that individually feature weak chaotic patchiness, we demonstrate that combining inferences across species and incorporating environmental data can greatly improve the predictive value of marine population genetics studies on small spatial scales. Significant correlations in genetic patterns of microsatellite markers among three species, kelp bass Paralabrax clathratus , Kellet’s whelk Kelletia kelletii and California spiny lobster Panulirus interruptus , in the Southern California Bight suggest that slight differences in diversity and pairwise differentiation across sampling sites are not simply noise or chaotic patchiness, but are ecologically meaningful. To test whether interspecies correlations potentially result from shared environmental drivers of genetic patterns, we assembled data on kelp bed size, sea surface temperature and estimates of site‐to‐site migration probability derived from a high resolution multi‐year ocean circulation model. These data served as predictor variables in linear models of genetic diversity and linear mixed models of genetic differentiation that were assessed with information–theoretic model selection. Kelp was the most informative predictor of genetics for all three species, but ocean circulation also played a minor role for kelp bass. The shared patterns suggest a single spatial marine management strategy may effectively protect genetic diversity of multiple species. This study demonstrates the power of environmental and ecological data to shed light on weak genetic patterns and highlights the need for future focus on a mechanistic understanding of the links between oceanography, ecology and genetic structure.