Jeffery Nicholas W, Vercaemer Benedikte, Stanley Ryan R E, Kess Tony, Dufresne France, Noisette Fanny, O'Connor Mary I, Wong Melisa C
Fisheries and Oceans Canada Bedford Institute of Oceanography Dartmouth Nova Scotia Canada.
Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre St. John's Newfoundland and Labrador Canada.
Evol Appl. 2024 Apr 21;17(4):e13671. doi: 10.1111/eva.13671. eCollection 2024 Apr.
A global decline in seagrass populations has led to renewed calls for their conservation as important providers of biogenic and foraging habitat, shoreline stabilization and carbon storage. Eelgrass () occupies the largest geographic range among seagrass species spanning a commensurately broad spectrum of environmental conditions. In Canada, eelgrass is managed as a single phylogroup despite occurring across three oceans and a range of ocean temperatures and salinity gradients. Previous research has focused on applying relatively few markers to reveal population structure of eelgrass, whereas a whole-genome approach is warranted to investigate cryptic structure among populations inhabiting different ocean basins and localized environmental conditions. We used a pooled whole-genome re-sequencing approach to characterize population structure, gene flow and environmental associations of 23 eelgrass populations ranging from the Northeast United States to Atlantic, subarctic and Pacific Canada. We identified over 500,000 SNPs, which when mapped to a chromosome-level genome assembly revealed six broad clades of eelgrass across the study area, with pairwise ranging from 0 among neighbouring populations to 0.54 between Pacific and Atlantic coasts. Genetic diversity was highest in the Pacific and lowest in the subarctic, consistent with colonization of the Arctic and Atlantic oceans from the Pacific less than 300 kya. Using redundancy analyses and two climate change projection scenarios, we found that subarctic populations are predicted to be potentially more vulnerable to climate change through genomic offset predictions. Conservation planning in Canada should thus ensure that representative populations from each identified clade are included within a national network so that latent genetic diversity is protected, and gene flow is maintained. Northern populations, in particular, may require additional mitigation measures given their potential susceptibility to a rapidly changing climate.
海草种群的全球衰退促使人们再次呼吁对其进行保护，因为它们是生物栖息地和觅食栖息地的重要提供者，对海岸线具有稳定作用，并能储存碳。大叶藻（）在海草物种中占据最大的地理范围，分布于相当广泛的环境条件下。在加拿大，大叶藻被作为一个单一的系统发育类群进行管理，尽管它分布在三大洋以及一系列海洋温度和盐度梯度区域。以往的研究主要集中在应用相对较少的标记来揭示大叶藻的种群结构，而采用全基因组方法来研究栖息在不同海洋盆地和局部环境条件下的种群间隐秘结构是很有必要的。我们采用混合全基因组重测序方法，对从美国东北部到加拿大的大西洋、亚北极和太平洋地区的23个大叶藻种群的种群结构、基因流和环境关联进行了表征。我们鉴定出超过50万个单核苷酸多态性（SNP），当将这些SNP映射到染色体水平的基因组组装上时，揭示了研究区域内大叶藻的六个主要分支，相邻种群之间的成对FST值范围从0到太平洋和大西洋海岸之间的0.54。遗传多样性在太平洋地区最高，在亚北极地区最低，这与不到30万年前从太平洋向北极和大西洋的殖民情况一致。通过冗余分析和两种气候变化预测情景，我们发现通过基因组偏移预测，亚北极种群预计可能更容易受到气候变化的影响。因此，加拿大的保护规划应确保每个已识别分支的代表性种群都纳入国家网络，以便保护潜在的遗传多样性并维持基因流。特别是北方种群，鉴于它们对快速变化的气候的潜在易感性，可能需要额外的缓解措施。
