Clegg Mark R, Wacker Alexander, Spijkerman Elly
Department of Ecology and Ecosystem Modelling, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
Department of Theoretical Aquatic Ecology and Ecophysiology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
Front Plant Sci. 2021 Aug 25;12:707541. doi: 10.3389/fpls.2021.707541. eCollection 2021.
Organisms often employ ecophysiological strategies to exploit environmental conditions and ensure bio-energetic success. However, the many complexities involved in the differential expression and flexibility of these strategies are rarely fully understood. Therefore, for the first time, using a three-part cross-disciplinary laboratory experimental analysis, we investigated the diversity and plasticity of photoresponsive traits employed by one family of environmentally contrasting, ecologically important phytoflagellates. The results demonstrated an extensive inter-species phenotypic diversity of behavioural, physiological, and compositional photoresponse across the Chlamydomonadaceae, and a multifaceted intra-species phenotypic plasticity, involving a broad range of beneficial photoacclimation strategies, often attributable to environmental predisposition and phylogenetic differentiation. Deceptively diverse and sophisticated strong (population and individual cell) behavioural photoresponses were observed, with divergence from a general preference for low light (and flexibility) dictated by intra-familial differences in typical habitat (salinity and trophy) and phylogeny. Notably, contrasting lower, narrow, and flexible compared with higher, broad, and stable preferences were observed in freshwater vs. brackish and marine species. Complex diversity and plasticity in physiological and compositional photoresponses were also discovered. Metabolic characteristics (such as growth rates, respiratory costs and photosynthetic capacity, efficiency, compensation and saturation points) varied elaborately with species, typical habitat (often varying more in eutrophic species, such as ), and culture irradiance (adjusting to optimise energy acquisition and suggesting some propensity for low light). Considerable variations in intracellular pigment and biochemical composition were also recorded. Photosynthetic and accessory pigments (such as chlorophyll , xanthophyll-cycle components, chlorophyll : and chlorophyll :carotenoid ratios, fatty acid content and saturation ratios) varied with phylogeny and typical habitat (to attune photosystem ratios in different trophic conditions and to optimise shade adaptation, photoprotection, and thylakoid architecture, particularly in freshwater environments), and changed with irradiance (as reaction and harvesting centres adjusted to modulate absorption and quantum yield). The complex, concomitant nature of the results also advocated an integrative approach in future investigations. Overall, these nuanced, diverse, and flexible photoresponsive traits will greatly contribute to the functional ecology of these organisms, addressing environmental heterogeneity and potentially shaping individual fitness, spatial and temporal distribution, prevalence, and ecosystem dynamics.
生物体常常采用生态生理策略来利用环境条件并确保生物能量的成功获取。然而，这些策略的差异表达和灵活性所涉及的诸多复杂性很少被完全理解。因此，我们首次采用三部分交叉学科实验室实验分析，研究了一类在环境上具有对比性且在生态上具有重要意义的植物鞭毛虫所采用的光响应特征的多样性和可塑性。结果表明，衣藻科在行为、生理和成分光响应方面存在广泛的种间表型多样性，以及多方面的种内表型可塑性，涉及一系列广泛的有益光适应策略，这通常归因于环境倾向和系统发育分化。观察到看似多样且复杂的强烈（种群和单个细胞）行为光响应，其偏离了对低光（和灵活性）的一般偏好，这是由典型栖息地（盐度和营养状况）和系统发育中的科内差异所决定的。值得注意的是，与淡水物种相比咸淡水和海洋物种表现出较低、较窄且灵活的偏好与较高、较宽且稳定的偏好形成对比。在生理和成分光响应方面也发现了复杂的多样性和可塑性。代谢特征（如生长速率、呼吸成本以及光合能力、效率、补偿点和饱和点）因物种、典型栖息地（在富营养物种中通常变化更大，如 ）和培养辐照度（进行调整以优化能量获取并显示出一些对低光的倾向）而有复杂变化。细胞内色素和生化成分也有相当大的变化。光合色素和辅助色素（如叶绿素 、叶黄素循环成分、叶绿素 ： 和叶绿素 ：类胡萝卜素比率、脂肪酸含量和饱和度比率）随系统发育和典型栖息地而变化（以在不同营养条件下调整光系统比率并优化遮荫适应、光保护和类囊体结构，特别是在淡水环境中），并随辐照度而变化（因为反应和捕获中心进行调整以调节吸收和量子产率）。结果的复杂且相互伴随的性质也倡导在未来研究中采用综合方法。总体而言，这些细微、多样且灵活的光响应特征将极大地促进这些生物体的功能生态学，应对环境异质性并潜在地塑造个体适应性、时空分布、流行程度和生态系统动态。
