Ocean School, YanTai University, Yantai, China.
Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
Mol Ecol. 2021 Aug;30(15):3840-3855. doi: 10.1111/mec.15996. Epub 2021 Jun 8.
Seagrasses play a vital role in structuring coastal marine ecosystems, but their distributional range and genetic diversity have declined rapidly in recent decades. To improve conservation of seagrass species, it is important to predict how climate change may impact their ranges. Such predictions are typically made with correlative species distribution models (SDMs), which can estimate a species' potential distribution under present and future climatic scenarios given species' presence data and climatic predictor variables. However, these models are typically constructed with species-level data, and thus ignore intraspecific genetic variability, which can give rise to populations with adaptations to heterogeneous climatic conditions. Here, we explore the link between intraspecific adaptation and niche differentiation in Thalassia hemprichii, a seagrass broadly distributed in the tropical Indo-Pacific Ocean and a crucial provider of habitat for numerous marine species. By retrieving and re-analysing microsatellite data from previous studies, we delimited two distinct phylogeographical lineages within the nominal species and found an intermediate level of differentiation in their multidimensional environmental niches, suggesting the possibility for local adaptation. We then compared projections of the species' habitat suitability under climate change scenarios using species-level and lineage-level SDMs. In the Central Tropical Indo-Pacific region, models for both levels predicted considerable range contraction in the future, but the lineage-level models predicted more severe habitat loss. Importantly, the two modelling approaches predicted opposite patterns of habitat change in the Western Tropical Indo-Pacific region. Our results highlight the necessity of conserving distinct populations and genetic pools to avoid regional extinction due to climate change and have important implications for guiding future management of seagrasses.
海草在构建沿海海洋生态系统中起着至关重要的作用，但近年来其分布范围和遗传多样性迅速减少。为了提高海草物种的保护水平，预测气候变化如何影响它们的分布范围非常重要。这种预测通常是通过相关的物种分布模型（SDM）来进行的，这些模型可以根据物种的存在数据和气候预测变量，来估计一个物种在当前和未来气候情景下的潜在分布。然而，这些模型通常是基于物种水平的数据构建的，因此忽略了种内遗传变异性，而这种变异性可能会导致具有适应异质气候条件的种群。在这里，我们探讨了在广泛分布于热带印度洋-太平洋地区的海草 Thalassia hemprichii 中，种内适应性和生态位分化之间的联系，它是许多海洋物种的重要栖息地提供者。通过检索和重新分析以前研究中的微卫星数据，我们在名义物种内划定了两个不同的系统发育谱系，并发现它们多维环境生态位之间存在中等程度的分化，表明存在局部适应的可能性。然后，我们使用种水平和谱系水平的 SDM 比较了物种在气候变化情景下的栖息地适宜性的预测结果。在中热带印度洋-太平洋地区，两种水平的模型都预测未来的分布范围会大幅缩小，但谱系水平的模型预测的栖息地损失更为严重。重要的是，这两种建模方法预测了西热带印度洋-太平洋地区的栖息地变化的相反模式。我们的研究结果强调了保护不同种群和遗传群体的必要性，以避免因气候变化而导致的区域性灭绝，并对指导未来的海草管理具有重要意义。
