Dipartimento di Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, UO Conisma, Via S. Alberto 163, 48123, Ravenna, Italy; CCMAR-CIMAR Centre of Marine Sciences, Universidade do Algarve, Faro, Portugal.
CCMAR-CIMAR Centre of Marine Sciences, Universidade do Algarve, Faro, Portugal.
Mar Environ Res. 2018 Jul;138:119-128. doi: 10.1016/j.marenvres.2018.04.013. Epub 2018 Apr 25.
Climate change is inducing shifts in species ranges across the globe. These can affect the genetic pools of species, including loss of genetic variability and evolutionary potential. In particular, geographically enclosed ecosystems, like the Mediterranean Sea, have a higher risk of suffering species loss and genetic erosion due to barriers to further range shifts and to dispersal. In this study, we address these questions for three habitat-forming seaweed species, Cystoseira tamariscifolia, C. amentacea and C. compressa, throughout their entire ranges in the Atlantic and Mediterranean regions. We aim to 1) describe their population genetic structure and diversity, 2) model the present and predict the future distribution and 3) assess the consequences of predicted future range shifts for their population genetic structure, according to two contrasting future climate change scenarios. A net loss of suitable areas was predicted in both climatic scenarios across the range of distribution of the three species. This loss was particularly severe for C. amentacea in the Mediterranean Sea (less 90% in the most extreme climatic scenario), suggesting that the species could become potentially at extinction risk. For all species, genetic data showed very differentiated populations, indicating low inter-population connectivity, and high and distinct genetic diversity in areas that were predicted to become lost, causing erosion of unique evolutionary lineages. Our results indicated that the Mediterranean Sea is the most threatened region, where future suitable Cystoseira habitats will become more limited. This is likely to have wider ecosystem impacts as there is a lack of species with the same ecological niche and functional role in the Mediterranean. The projected accelerated loss of already fragmented and disturbed populations and the long-term genetic effects highlight the urge for local scale management strategies that sustain the capacity of these habitat-forming species to persist despite climatic impacts while waiting for global emission reductions.
气候变化正在导致全球物种分布范围发生变化。这些变化可能会影响物种的遗传基因库，包括遗传变异性和进化潜力的丧失。特别是，像地中海这样地理上封闭的生态系统，由于进一步的分布范围变化和扩散的障碍，面临着更高的物种丧失和遗传侵蚀的风险。在这项研究中，我们针对大西洋和地中海地区三种生境海藻物种（Cystoseira tamariscifolia、C. amentacea 和 C. compressa）的整个分布范围，回答了以下三个问题：1）描述其种群遗传结构和多样性；2）模拟当前和预测未来的分布情况；3）评估预测未来分布范围变化对其种群遗传结构的影响，根据两种对比的未来气候变化情景。在这两种气候情景下，三种物种的分布范围内都预测到适宜区域的净损失。在地中海地区，C. amentacea 的损失尤其严重（在最极端的气候情景下减少了 90%），这表明该物种可能面临潜在灭绝的风险。对于所有物种，遗传数据显示出非常分化的种群，表明种群间的连通性较低，而在预测将消失的地区，遗传多样性较高且独特，导致独特的进化谱系的侵蚀。我们的研究结果表明，地中海地区是受威胁最严重的地区，未来适宜的 Cystoseira 生境将变得更加有限。由于地中海缺乏具有相同生态位和功能作用的物种，这可能会对更广泛的生态系统产生影响。预测加速丧失已经碎片化和受到干扰的种群，以及长期的遗传影响，突显了迫切需要采取地方规模的管理策略，以维持这些生境形成物种的生存能力，尽管受到气候影响，但同时也在等待全球减排。
