Data from: Intraspecific and interspecific variation in thermotolerance and photoacclimation in Symbiodinium dinoflagellates

Light and temperature are major drivers in the ecology and biogeography of symbiotic dinoflagellates living in corals and other cnidarians. We examined variations in physiology among 11 strains comprising five species of clade A Symbiodinium. We grew cultures at 26°C (control) and 32°C (high temperature) over a duration of 18 days while measuring growth and photochemical efficiency (Fv/Fm). Responses to thermal stress ranged from susceptible to tolerant across species and strains. Most strains exhibited a decrease in cell densities and Fv/Fm when grown at 32°C. Tolerance to high temperature (T32) was calculated for all strains, ranging from 0 (unable to survive at high temperature) to 1 (able survive at high temperature). There was substantial variation in thermotolerance across species and among strains. One strain had a T32 close to 1, indicating that growth was not reduced at 32°C for only this one strain. To evaluate the combined effect of temperature and light on physiological stress, we selected three strains with different levels of thermotolerance (tolerant, intermediate and susceptible) and grew them under five different light intensities (65, 80, 100, 240 and 443 µmol quanta m−2 s−1) at 26 and 32°C. High irradiance exacerbated the effect of high temperature, particularly in strains from thermally sensitive species. This work further supports the recognition that broad physiological differences exist not only among species within Symbiodinium clades, but also among strains within species demonstrating that thermotolerance varies widely between species and among strains within species.

光照与温度是栖息于珊瑚及其他刺胞动物体内的共生甲藻的生态与生物地理分布的核心调控因子。本研究针对11个菌株展开生理特征差异分析，这些菌株分属于A簇（clade A）虫黄藻（Symbiodinium）的5个物种。我们将菌株分别置于26℃（对照组）与32℃（高温胁迫）环境下培养18天，期间同步测定其生长速率与光化学效率（Fv/Fm）。不同物种及菌株对热胁迫的响应跨度较大，从敏感型到耐受型均有分布。多数菌株在32℃培养条件下，细胞密度与Fv/Fm值均出现显著下降。我们为所有菌株计算了高温耐受指数（T32），其取值范围为0（无法在高温环境下存活）至1（可在高温环境下存活）。不同物种间以及菌株间的耐热性存在显著差异。仅有1个菌株的T32值接近1，表明该菌株在32℃环境下的生长未受抑制。为评估温度与光照对生理胁迫的联合效应，我们选取了3个耐热性水平各异的菌株（耐受型、中间型与敏感型），分别在26℃与32℃环境下，以5种不同光照强度（65、80、100、240及443 μmol quanta m⁻² s⁻¹）进行培养。高光强会加剧高温胁迫的负面影响，这一效应在热敏性物种来源的菌株中尤为显著。本研究进一步证实，虫黄藻簇内不仅不同物种间存在广泛的生理差异，同一物种内的不同菌株间也存在显著生理差异，即耐热性在物种间以及物种内菌株间均存在广泛变异。