Diapause, quiescence, hatching requirements: What we can learn from large freshwater branchiopods (Crustacea:Branchiopoda:Anostraca, Notostraca, Conchostraca)
Diapause, quiescence, hatching requirements: What we can learn from large freshwater branchiopods (Crustacea:Branchiopoda:Anostraca, Notostraca, Conchostraca)
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DOI：
10.1007/bf00016809
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发表时间：
1996-03-01
期刊：
影响因子：
2.6
通讯作者：
Brendonck, L
中科院分区：
文献类型：
--
作者：
Brendonck, L
大型淡水鳃足动物的休眠受内源（滞育）或外源（静止）控制的程度并不总是清楚。假设这两个过程甚至发生在同一窝内。基于常见的滞育失活过程（例如干燥、冬眠和休息）的有效性，可以说滞育不是控制大型淡水鳃足动物卵反应性的一般过程。只有在有限的情况下，才能找到这些治疗产生积极影响的明确证据。除了少数例外，活化包囊的孵化受到特定条件的影响，这些条件甚至可能在同种群体之间有所不同。一般来说，每个物种（甚至种群）都有一个特定的温度范围或制度来实现最佳孵化性能。在具有充足光照和氧气的合适热环境中，孵化总是由低渗透介质引起。大多数物种不稳定的孵化模式被认为是对可变临时栖息地的适应。孵化一般持续数天甚至数周，但最高峰通常出现在孵化的第一天或第二天。仅在亚热带/沙漠物种中发现孵化率较低，这可能反映了成功繁殖的机会较低。卵库中繁殖体通过休眠和低电导率孵化产生的后代，加上专性卵生和无性生命周期阶段的缺乏，被认为对临时环境具有高度适应性。这使得大型鳃足类动物能够自上寒武世以来生存下来。
The extent to which dormancy in large freshwater branchiopods is controlled endogenously (diapause) or exogenously (quiescence) is not always clear. It is assumed that both processes occur even within the same brood. Based on the effectiveness of common diapause-deactivating processes such as desiccation, hibernation, and resting, it can be stated that diapause is not a general process controlling responsiveness of large freshwater branchiopod eggs. Only in limited cases unequivocal evidence for the positive influence of these treatments is found.With few exceptions, hatching of activated cysts is effected by specific conditions that may even differ among conspecific populations. Generally, each species (or even population) has a specific temperature range or regime for optimal hatching performance. In a suitable thermal environment with sufficient light and oxygen, hatching is invariably invoked by a low osmotic medium.The erratic hatching pattern in most species is thought to be an adaptation to the variable temporary habitat. Hatching is generally spread over several days or even weeks, but the highest peak usually occurs on the first or second day of hatching. Low hatching percentages were found only in subtropical/desert species and may be a reflection of the low chances for successful reproduction. Generation carry-over of propagules in the egg bank by dormancy, and hatching at low conductivity, are, together with obligate oviparity and absence of an asexual life cycle phase, thought to be highly adaptive to the temporary environment. This enabled large branchiopods to survive since the Upper Cambrian.