Verma Arjun, Hughes David J, Harwood D Tim, Suggett David J, Ralph Peter J, Murray Shauna A
Climate Change Cluster University of Technology Sydney Ultimo NSW Australia.
Cawthron Institute Nelson New Zealand.
Ecol Evol. 2020 May 21;10(13):6257-6273. doi: 10.1002/ece3.6358. eCollection 2020 Jul.
Genetic diversity in marine microbial eukaryotic populations (protists) drives their ecological success by enabling diverse phenotypes to respond rapidly to changing environmental conditions. Despite enormous population sizes and lack of barriers to gene flow, genetic differentiation that is associated with geographic distance, currents, and environmental gradients has been reported from planktonic protists. However, for benthic protists, which have reduced dispersal opportunities, phylogeography and its phenotypic significance are little known. In recent years, the East Australian Current (EAC) has intensified its southward flow, associated with the tropicalization of temperate waters. Benthic harmful algal species have been increasingly found in south-eastern Australia. Yet little is known about the potential of these species to adapt or extend their range in relation to changing conditions. Here, we examine genetic diversity and functional niche divergence in a toxic benthic dinoflagellate, cf. along a 1,500 km north-south gradient in southeastern Australia. Sixty-eight strains were established from eight sampling sites. The study revealed long-standing genetic diversity among strains established from the northern-most sites, along with large phenotypic variation in observed physiological traits such as growth rates, cell volume, production of palytoxin-like compounds, and photophysiological parameters. Strains from the southern populations were more uniform in both genetic and functional traits, and have possibly colonized their habitats more recently. Our study reports significant genetic and functional trait variability in a benthic harmful algal species, indicative of high adaptability, and a possible climate-driven range extension. The observed high trait variation may facilitate development of harmful algal blooms under dynamic coastal environmental conditions.
海洋微生物真核生物种群（原生生物）的遗传多样性通过使多样的表型能够快速响应不断变化的环境条件，推动了它们在生态上的成功。尽管浮游原生生物的种群数量巨大且基因流动没有障碍，但已有报道称其存在与地理距离、洋流和环境梯度相关的遗传分化。然而，对于扩散机会减少的底栖原生生物，系统地理学及其表型意义却鲜为人知。近年来，东澳大利亚洋流（EAC）向南流动加剧，这与温带水域的热带化有关。在澳大利亚东南部，底栖有害藻华物种越来越多地被发现。然而，关于这些物种在不断变化的条件下适应或扩大其分布范围的潜力，我们却知之甚少。在这里，我们研究了一种有毒底栖甲藻（cf.）在澳大利亚东南部1500公里南北梯度上的遗传多样性和功能生态位分化。从八个采样点建立了68个菌株。研究揭示了从最北部采样点分离出的菌株之间长期存在的遗传多样性，以及在观察到的生理特征（如生长速率、细胞体积、类沙海葵毒素化合物的产生和光生理参数）方面的巨大表型变异。来自南部种群的菌株在遗传和功能特征上更为一致，并且可能是最近才在其栖息地定殖的。我们的研究报告了一种底栖有害藻华物种中显著的遗传和功能特征变异性，这表明其具有高适应性，以及可能因气候驱动的分布范围扩展。观察到的高特征变异性可能会促进在动态的沿海环境条件下有害藻华的发展。
