Different thermal stimuli initiate hatching of Daphnia diapausing eggs originating from lakes and temporary waters
Different thermal stimuli initiate hatching of Daphnia diapausing eggs originating from lakes and temporary waters
复制标题
不同的热刺激引发源自湖泊和临时水域的水蚤滞育卵的孵化
作者：
Jacek Radzikowski;Katarzyna Krupińska;M. Ślusarczyk
同时孵化水蚤休眠卵从一些不同的湖泊和池塘使用一套孵化线索可能很难实现的环境条件之间的水体差异很大。因此，最佳孵化条件的ephippial鸡蛋源于浅临时沃茨可能不同于那些发现在大型湖泊。我们的研究的目的是比较最佳的热条件孵化的水蚤在永久性湖泊和浅临时池塘中发现的ephippial卵。我们使用的ephippial卵的水蚤从longispina物种复杂起源于两个临时城市池塘和两个深湖在波兰。在野外和实验室工作的所有阶段，均对卵进行保护，防止过热，以防止卵活化或死亡。在不应期（在凉爽和黑暗条件下强制储存）后，将ephippia在6个不同温度（6、9、12、15、18和21 ℃）下在16：8 L：D光方案下孵育。我们的研究结果表明，孵化栖息在湖泊或池塘的水蚤休眠卵可能需要不同的热条件。在所有测试的孵化温度下，来自临时沃茨的卵孵化成功率相对较高（30-56%），而来自深湖的卵孵化成功率较低（7-37%），且与水温呈负相关。来自临时池塘和湖泊的海马卵的不同孵化反应可能反映了其原生栖息地孵化期间的典型热条件。在温带的深水湖泊中，水蚤的孵化通常发生在早春的低水温期间，而在浅水池塘中，水蚤的孵化可能在一年中发生，水温从几摄氏度到十几摄氏度不等。
The simultaneous hatching of Daphnia resting eggs from a number of different lakes and ponds using one set of hatching cues can be difficult to achieve as environmental conditions differ considerably between water bodies. Therefore, optimal hatching conditions for ephippial eggs originating from shallow temporary waters may differ from those found in large lakes. The aim of our study was to compare the optimal thermal conditions for hatching ephippial eggs of Daphnia found in permanent lakes and those from shallow temporary ponds. We used ephippial eggs of Daphnia from the longispina species complex originating from two temporary city ponds and two deep lakes in Poland. The ephippia were protected against overheating at all stages of the field and laboratory work to prevent activation or killing of the eggs. After a refractory period (imposed storage in cool and dark conditions), ephippia were incubated at six different temperatures (6, 9, 12, 15, 18 and 21 °C) under a 16:8 L:D light regime. Our results indicate that hatching of resting eggs of Daphnia that inhabit lakes or ponds may require different thermal conditions. The hatching success of ephippial eggs originating from temporary waters was relatively high (30–56%) at all tested incubation temperatures, while for the ephippial eggs from the deep lakes it was lower (7–37%) and inversely related to water temperature. The divergent hatching responses of the ephippial eggs originating from temporary pools and lakes may reflect the typical thermal conditions during hatching in their native habitats. While in the deep lakes of the temperate zone Daphnia hatching typically occurs during the low water temperatures of early spring, in shallow ponds Daphnia hatching may occur throughout the year at varying water temperatures, from a few to over a dozen degrees Celsius.