Data from: Seasonality and growth in tropical freshwater ectotherm vertebrates: results from one-year experimentation in the African grey bichir, giraffe catfish, and the West African mud turtle

Growth in ectotherm vertebrates is strongly rhythmed by seasonal variation in environmental parameters. To track the seasonal variation in ancient times in a continental and tropical context, we aim to develop a method based on the use of the growth rate of fossil ectotherm vertebrates (actinopterygians and chelonians) influenced by seasonal environmental fluctuations they experienced in their lifetime. However, the impact of environmental parameters on growth, positive or negative, and its intensity, depends on the taxa considered and data are scarce for tropical species. For one year, an experiment was conducted to better understand the effect of seasonal variation in environmental parameters (food abundance, temperature, and photoperiod) on the somatic growth rate of three species of tropical freshwater ectotherm vertebrates: the fishes Polypterus senegalus and Auchenoglanis occidentalis and the turtle Pelusios castaneus. Mimicking seasonal shifts expected to be experienced by the animals in the wild, the experiment highlighted the preponderant effect of food abundance on the growth rate of those three species. Water temperature variation had a significant effect on the growth rate of Po. senegalus and Pe. castaneus. Moreover, the photoperiod demonstrated no significant effect on the growth of the three species. The duration of application of starvation or cool water conditions, ranging from 1 to 3 months, did not affect the growth rate of the animals. However, Pe. castaneus showed a temporary sensitivity to the return of ad libitum feeding or of warm water, after a period of starvation or cool water, by a period of compensatory growth. Finally, this experiment revealed, in the three species, fluctuations in the growth rate under controlled and constant conditions. This variation, similar to the variation in precipitation and temperature observed in their native environment, could be linked to a strong effect of an internal rhythm controlling somatic growth rate.

变温脊椎动物（ectotherm vertebrates）的生长节律显著受环境参数的季节性变化调控。为重建大陆热带背景下的古代季节性环境变化，我们拟开发一种研究方法，该方法依托受生存期间季节性环境波动影响的化石变温脊椎动物——辐鳍鱼（actinopterygians）与龟类（chelonians）——的生长速率。然而，环境参数对生长的正负效应及其强度因类群而异，且热带物种的相关研究数据较为匮乏。为进一步明晰环境参数（食物丰度、水温、光周期）的季节性变化对三种热带淡水变温脊椎动物躯体生长速率的影响，本研究开展了为期一年的实验。受试物种包括塞内加尔多鳍鱼（Polypterus senegalus）、西非鲶（Auchenoglanis occidentalis）以及西非侧颈龟（Pelusios castaneus）。实验模拟了这些物种在野生环境中会经历的季节性环境变化，结果显示食物丰度对这三个物种的生长速率具有主导性影响。水温变化对塞内加尔多鳍鱼与西非侧颈龟的生长速率具有显著影响。此外，光周期对这三个物种的生长无显著影响。禁食或低温水环境的持续时长（1至3个月不等）并未对受试动物的生长速率产生显著影响。不过，当结束一段时长的禁食或低温水环境并恢复自由采食或回暖水温时，西非侧颈龟会出现一段暂时性的补偿性生长阶段，展现出对环境变化的敏感性。最后，本实验发现，即便在可控恒定的环境条件下，三个物种的生长速率仍存在波动。该波动与它们原生环境中观测到的降水与温度变化模式相似，可能与调控躯体生长速率的内在节律的强调控效应相关。