Genetic heterogeneity of two bioeconomically important kelp species along the Norwegian coast

Abstract

25Knowledge of genetic diversity among wild populations is becoming increasingly important as more species are 26 recognized for their bioeconomic value. Industrialization of natural resources, such as kelp in the marine 27 shallow sublittoral zone through cultivation and wild-harvesting, may lead to extensive translocation and local 28 population decimation. Without adequate resilience in the form of genetic diversity within and across 29 populations and given the potential introduction of deleterious alleles from translocations, such 30 anthropogenically pressured populations may not be able to sufficiently respond to future climate and other 31 stressors. Here we provide an assessment of the genetic heterogeneity of two bioeconomically important kelp 32 species, Laminaria hyperborea and Saccharina latissima, across the Norwegian coastal region from South 33 (57°N) to North (78°N), by applying microsatellite genotyping. Isolation by distance was found for both kelp 34 species when comparing genetic distance to geographic distance. L. hyperborea clustered into four distinct 35 genetic groups corresponding to distinct geographical ecoregions, whereas S. latissima did not show equally 36 strong geographical structuring but separated into three geographical clusters along the Norwegian coast. No 37 genetic differentiation was found within the Norwegian Skagerrak region, corroborating previous findings. The 38 identified genetic clustering of both kelp species supports the retention of established management regions along 39the Norwegian coast and argues for the continuation of a regional focused management plan for kelp resources. 40 2 Further, the results demonstrate that care should be taken to prevent translocation of kelp between ecoregions in 41 the ongoing industrialization of kelp cultivation, to maintain a healthy coastal ecosystem and sound natural 42 population genetic diversity. 43 44

Seascape Genomics of the Sugar Kelp Saccharina latissima Along the North Eastern Atlantic Latitudinal Gradient

“…A pattern of increasing genetic diversity with increasing latitude had previously been observed for European S. latissima at several spatial scales [29,33], a pattern opposite to that expected under the hypothesis of latitudinal cline of genetic variability, though ours is the first study to investigate the hypothesis of a latitudinal cline of genetic variability across the entire eastern Atlantic range of this kelp species. There are several potential non-mutually exclusive reasons, including both historical and contemporary causes, that may explain the reported patterns of S. latissima genetic diversity.…”

“…Overall, the strong genetic structuring that we report here for S. latissima is in agreement with previous analyses of the population structure in this kelp species [29,33,70]. However, compared with the previous published studies, the high discriminant power of SNP markers developed as part of this study suggests that these markers could prove very useful for kelp aquaculture to detect individual migrants (or genetic pollution) between S. latissima populations when separated by at least 300 km.…”

“…The general trend revealed a reduction in genetic diversity with increasing latitude that was linked with episodes of contraction/expansion of the species' ranges during the Last Glacial Maximum (LGM) [6,23,24]. In addition, levels of connectivity between marine forests of a number of European kelp species have been investigated at different spatial scales ranging from less than 1 km to in excess of hundreds of kilometers (Laminaria digitata: [25][26][27][28]; L. hyperborea: [25,29,30]; L. ochroleuca: [11]; Saccorhiza polyschides: [24]; Saccharina latissima: [29,[31][32][33][34]. All of these studies agreed that the levels of connectivity were generally very low.…”

Population Genetics of Sugar Kelp Throughout the Northeastern United States Using Genome-Wide Markers

“…Breeding samples across these two regions is currently prohibited due to conservation concerns. Nonetheless, similar to other studies (Evankow et al, 2019), our recommendation supports the precautionary principle to only use regional ecotypes for cultivation, and to not interbreed kelp strains separated by Cape Cod. We also reveal a novel SNP association with a morphological trait and additional polymorphisms that may have been subject to selection in sugar kelp.…”

Cultivar Development of Kelps for Commercial Cultivation—Past Lessons and Future Prospects

“…Recently, a number of population genetic analyses using molecular marker data have been conducted in order to describe the geographical pattern of genetic variation in kelp species. For example, based on microsatellite data, it has been shown that there is statistically significant genetic differentiation among both European and North-American populations of S. latissima, at least at distances above around 100 km (Guzinski et al, 2016;Nielsen et al, 2016;Paulino et al, 2016;Breton et al, 2018;Evankow et al, 2018;Luttikhuizen et al, 2018;Mooney et al, 2018). In spite of the genetic differentiation between populations, analysis of molecular variance indicated that most of the genetic variation (>90%) was found within populations rather than between populations (Breton et al, 2018;Mooney et al, 2018).…”