Responses of population structure and genomic diversity to climate change and fishing pressure in a pelagic fish.

The responses of marine species to environmental changes and anthropogenic pressures (e.g., fishing) interact with ecological and evolutionary processes that are not well understood. Knowledge of changes in the distribution range and genetic diversity of species and their populations into the future is essential for the conservation and sustainable management of resources. Almaco jack (Seriola rivoliana) is a pelagic fish with high importance to fisheries and aquaculture in the Pacific Ocean. In this study, we assessed contemporary genomic diversity and structure in loci that are putatively under selection (outlier loci) and determined their potential functions. Using a combination of genotype-environment association, spatial distribution models, and demogenetic simulations, we modeled the effects of climate change (under three different RCP scenarios) and fishing pressure on the species' geographic distribution and genomic diversity and structure to 2050 and 2100. Our results show that most of the outlier loci identified were related to biological and metabolic processes that may be associated with temperature and salinity. The contemporary genomic structure showed three populations-two in the Eastern Pacific (Cabo San Lucas and Eastern Pacific) and one in the Central Pacific (Hawaii). Future projections suggest a loss of suitable habitat and potential range contractions for most scenarios, while fishing pressure decreased population connectivity. Our results suggest that future climate change scenarios and fishing pressure will affect the genomic structure and genotypic composition of S. rivoliana and lead to loss of genomic diversity in populations distributed in the eastern-central Pacific Ocean, which could have profound effects on fisheries that depend on this resource.

Las respuestas de las especies marinas ante los cambios ambientales y presiones antropogénicas (por ejemplo, la sobrepesca) interactúan con procesos ecológicos y evolutivos que no se comprenden bien. El conocimiento del cambio en el rango de distribución y la diversidad genética de las especies y sus poblaciones en el futuro es fundamental para la conservación y gestión sostenible de los recursos. El jurel (Seriola rivoliana) es un pez pelágico de gran importancia para la pesca y la acuicultura en el Océano Pacífico. En este estudio, evaluamos la diversidad y estructura genómica contemporánea en loci que supuestamente están bajo selección (loci atípicos) y determinamos sus funciones potenciales. Se utilizó la combinación de métodos de asociación genotipo-ambiente, modelos de distribución espacial y simulaciones demogenéticas, para modelar los efectos del cambio climático (bajo tres escenarios RCP diferentes) y presión de pesca sobre la distribución geográfica de la especie, la diversidad y estructura genómica para los años 2050 y 2100. Nuestros resultados mostraron que la mayoría de los loci atípicos están relacionados con procesos biológicos y metabólicos que pueden estar asociados con la temperatura y la salinidad. La estructura genómica contemporánea mostró tres poblaciones: dos en el Pacífico oriental (Cabo San Lucas y el Pacífico oriental) y una en el Pacífico central (Hawai). Las proyecciones futuras sugieren una pérdida de hábitat idóneo y posibles contracciones del área de distribución para la mayoría de los escenarios, mientras que la presión de la pesca redujo la conectividad de las poblaciones. Nuestros resultados sugieren que los escenarios de cambio climático y la presión pesquera afectarán la estructura genómica y la composición genotípica de S. rivoliana y conducirán a la pérdida de diversidad genómica en las poblaciones distribuidas en el Océano Pacífico centro-oriental, lo que podría tener efectos en las pesquerías que dependen de este recurso.

Genetic diversity and structure of circumtropical almaco jack, Seriola rivoliana: tool for conservation and management.

The almaco jack, Seriola rivoliana, is a circumtropical pelagic fish of importance both in commercial fisheries and in aquaculture. To understand levels of genetic diversity within and among populations in the wild, population genetic structure and the relative magnitude of migration were assessed using mtDNA sequence data and single nucleotide polymorphisms (SNPs) from individuals sampled from locations in the Pacific and Atlantic Oceans. A total of 25 variable sites of cytochrome c oxidase subunit 1 and 3678 neutral SNPs were recovered. Three genetic groups were identified, with both marker types distributed in different oceanic regions: Pacific-1 in central Pacific, Pacific-2 in eastern Pacific and Atlantic in western Atlantic. Nonetheless, the analysis of SNP identified a fourth population in the Pacific coast of Baja California Sur, Mexico (Pacific-3), whereas that of mtDNA did not. This mito-nuclear discordance is likely explained by a recently diverged Pacific-3 population. In addition, two mtDNA haplogroups were found within the western Atlantic, likely indicating that the species came into the Atlantic from the Indian Ocean with historical gene flow from the eastern Pacific. Relative gene flow among ocean basins was low with r m < 0.2, whereas in the eastern Pacific it was asymmetric and higher from south to north (r m > 0.79). The results reflect the importance of assessing genetic structure and gene flow of natural populations for the purposes of sustainable management.