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, Ostreopsis cf. siamensis, 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.

中文翻译：

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沿东澳大利亚洋流经纬度梯度沉积的有毒底栖海洋微生物真核生物中植物谱结构的功能意义。

海洋微生物真核生物种群（原生生物）的遗传多样性通过使不同的表型能够迅速响应不断变化的环境条件来推动其生态学成功。尽管人口众多，基因流动没有障碍，但浮游生物界人士报告了与地理距离，潮流和环境梯度有关的遗传分化。然而，对于底栖生物而言，其散布机会减少了，相谱及其表型意义鲜为人知。近年来，与温带水热带化相关的东澳大利亚洋流（EAC）加剧了其向南流动。在澳大利亚东南部越来越发现有底栖有害藻类。关于这些物种适应条件变化或扩展其范围的潜力知之甚少。在这里，我们研究了有毒底栖鞭毛藻的遗传多样性和功能性生态位差异，骨质疏松症cf. 暹罗沿澳大利亚东南部1500公里的南北向倾斜。从八个采样点建立了68个菌株。该研究揭示了在最北端建立的菌株之间的长期遗传多样性，以及观察到的生理特征（如生长速率，细胞体积，类毒素化合物的产生和光生理参数）的大表型变异。来自南部种群的菌株在遗传和功能性状上都更加统一，并且可能在最近的殖民地中得以定居。我们的研究报告了底栖有害藻类物种的显着遗传和功能性状变异性，表明其高度适应性以及可能的气候驱动范围扩展。