Evolutionary Genomics Group, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland, South Africa.
Hawai'i Institute of Marine Biology, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, USA.
J Environ Manage. 2020 Feb 1;255:109831. doi: 10.1016/j.jenvman.2019.109831. Epub 2019 Dec 26.
Zostera capensis is a keystone species providing essential ecosystem services to southern African coastal systems. Like most seagrasses globally, Z. capensis is declining and under threat from anthropogenic pressures, and indicators of seagrass health and resilience may be of interest in preventing further declines. As intraspecific diversity is an important component of resilience, we used a pooled RADseq approach to generate genome-wide measures of variation across the entire South African distribution of Z. capensis. Using nucleotide diversity, heterozygosity and allelic richness we tested for associations with fine-scale anthropogenic pressure data compiled by the South African National Biodiversity Assessment using generalised linear models. Increased fishing effort, habitat loss, sand mining and a change in estuary flow dynamics were found to play an important role in decreasing nucleotide diversity and expected heterozygosity, most likely due to the loss of less resilient genotypes as a result of direct physical damage or indirect consequences. As the building block for adaptation, nucleotide diversity is particularly important for resilience. Because of this, as well as the fact that nucleotide diversity displayed the most distinct difference between the west and east coast, and responded most strongly to anthropogenic pressures, we suggest that this may be a useful measure for monitoring genetic or genomic variation. As genomic diversity influences resilience and resistance to disturbances, the remaining diversity in South African seagrass beds urgently needs to be conserved through restoration efforts and careful management of pressures.
南非产海菖蒲是一种关键物种，为南非沿海生态系统提供了重要的生态系统服务。与全球大多数海草一样，南非产海菖蒲正在减少，并且受到人为压力的威胁，因此，海草健康和恢复力的指标可能有助于防止进一步减少。由于种内多样性是恢复力的重要组成部分，我们使用汇集 RADseq 方法来生成整个南非产海菖蒲分布的全基因组变异的衡量标准。我们使用核苷酸多样性、杂合度和等位基因丰富度，使用广义线性模型测试了与南非国家生物多样性评估汇编的精细尺度人为压力数据的关联。发现捕鱼力度增加、生境丧失、采砂以及河口流动力变化对减少核苷酸多样性和预期杂合度起着重要作用，这很可能是由于直接物理损伤或间接后果导致较少弹性基因型的丧失。作为适应的基础，核苷酸多样性对恢复力尤为重要。由于这一点，以及核苷酸多样性在西海岸和东海岸之间表现出最明显的差异，并且对人为压力的反应最强烈，因此我们建议这可能是监测遗传或基因组变异的有用指标。由于基因组多样性影响恢复力和对干扰的抵抗力，南非海草床中剩余的多样性急需通过恢复工作和对压力的谨慎管理来保护。
