Abstract
An assessment of genetic diversity of marine populations is critical not only for the understanding and preservation of natural biodiversity but also for its economic potential. As commercial demand rises for marine resources, it is critical to generate baseline information for monitoring wild populations. Furthermore, anthropogenic stressors on the coastal environment, such as warming sea surface temperatures and overharvesting of wild populations, are leading to the destruction of keystone marine species such as kelps. In this study, we conducted a fine-scale genetic analysis using genome-wide high-density markers on Northwest Atlantic sugar kelp species, Saccharina latissima and putative species, Saccharina angustissima . The population structure for a total of 149 samples from the Gulf of Maine (GOM) and Southern New England (SNE) was investigated using AMOVA, Fst, admixture, and PCoA. Genome-wide association analyses were conducted for six morphological traits, and the extended Lewontin and Krakauer (FLK) test was used to detect selection signatures. Our results indicate that the GOM region is moderately more heterogeneous than SNE. While admixture was observed between regions, these results confirm that Cape Cod acts as a biogeographic barrier for sugar kelp gene flow. We detected one significant SNP (P-value=2.03×10 -7 ) associated with stipe length, and 243 SNPs with higher-than-neutral differentiation. The findings of this study provide fundamental knowledge on sugar kelp population genetics for future monitoring, managing and potentially restoring wild populations, as well as assisting in selective breeding to improve desirable traits for cultivation and bioenergy production.
Highlights
Brown macroalgae in the order Laminariales (Phaeophyceae), or kelp, are keystone species in the near-shore temperate marine environment (Dayton, 1985)
Blade lengths ranged from 84.5 ± 37.5 cm for Pine Island to 227.4 ± 22.9 cm for Mount Desert Rock; blade widths at 10 cm ranged from 2.2 ± 0.3 cm for Giant Staircase to 24.6 ± 1.6 cm for Downeast Institute; blade widths at the widest ranged from 3.4 ± 0.3 mm for Giant Staircase to 41.4 ± 2.3 mm for Orr’s Island; stipe diameter ranged from 2.17 ± 0.61 mm for Giant Staircase to 14.43 ± 2.17 mm for Downeast Institute; stipe lengths ranged from 4.8 ± 0.6 cm for Giant Staircase to 122.7 ± 18.9 cm for Lubec Light; blade thickness ranged from 0.8 ± 0.00 mm for Pine Island to 2.28 ± 0.14 mm for Downeast Institute
We investigated the genetic population structure of wild sugar kelp (Saccharina sp.) populations in the Northeastern United States using genome-wide SNP data
Summary
Brown macroalgae in the order Laminariales (Phaeophyceae), or kelp, are keystone species in the near-shore temperate marine environment (Dayton, 1985). For humans around the globe, kelp has long provided both a food source and bioextracts with various commercial applications (Bartsch et al, 2008) Besides their important ecological roles and the wellestablished kelp cultivation practices in coastal Asian countries, there is growing interest in macroalgal cultivation in Europe, South America, and throughout the United States of America (Augyte et al, 2017; Buschmann et al, 2017; Campbell et al, 2019; Grebe et al, 2019; Kim et al, 2019; Goecke et al, 2020). Intensive selection pressure during the marine crop domestication process leads to favoring certain phenotypic traits (Zhang et al, 2017) These mechanisms may promote adaptive divergence between cultivated seaweeds and wild populations, and it is, critical to understand wild phenotypic traits as they undergo domestication. This will foster future breeding and cultivation efforts in a sustainable and informed manner for managers, conservation groups, researchers, and industry
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