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Dryad

Nereocystis luetkeana microsatellite data (Genepop format)

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Nov 07, 2023 version files 119.44 KB

Abstract

In temperate regions, one of the most critical determinants of present range-wide genetic diversity was the Pleistocene climate oscillations, the most recent one created by the last glacial maximum (LGM). This study aimed to describe Nereocystis luetkeana genetic structure across its entire range (Alaska to California) and test different models of population connectivity within the Salish Sea. This region was colonized after the LGM and has been under increased disturbance in recent decades. We utilized microsatellite markers to study N. luetkeana genetic diversity at 53 sites across its range. Using higher sampling density in the Salish Sea, we employed a seascape genetics approach and tested isolation by hydrodynamic transport and environment models. At the species distribution scale, we found four main groups of genetic co-ancestry, Alaska; Washington with Vancouver Island's outer coast and Juan de Fuca Strait; Washington's inner Salish Sea; and Oregon with California. The highest allelic richness (AR) levels were found in California, near the trailing range edge, although AR was also high in Alaska. The inner Salish Sea region had the poorest diversity across the species distribution. Nevertheless, a pattern of isolation by hydrodynamic transport and environment was supported in this region. The levels of allelic richness and genetic differentiation suggest that during the LGM, bull kelp had both northern and southern glacial refugia in Haida Gwaii and Central California, respectively. Genetic diversity in Northern California sites seems resilient to recent disturbances, whereas the low levels of genetic diversity in the inner Salish Sea are concerning.