A Big Bang or small bangs? Effects of biotic environment on hatching
A Big Bang or small bangs? Effects of biotic environment on hatching
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大爆炸还是小刘海？
DOI：
10.4081/jlimnol.2008.100
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发表时间：
2008
影响因子：
1.6
通讯作者：
M. Manca
中科院分区：
文献类型：
--
作者：
R. Bozelli;Maurizio Tonsi;F. Sandrini;M. Manca
滞育的开始和结束是枝蚧生活史中两个重要的转折点。环境变量对这些过程动态的影响仍然值得注意，特别是生物因素的作用。在本文中，我们专注于出现滞育，测试（1）是否ephippia的水蚤obtusa Kurz可以评估存在于水中的典型的食虫鱼类或介形类，以及（2）是否这样的评估结果在孵化策略的变化。从D. obtusa ephippial卵在对照组和处理组之间没有差异，其中可以检测到鱼类或介形类的存在（ANOVA，P = 0.884）。但孵化动态不同，对照组中大多数卵在第4天同步孵化（占总孵化数的83.3%），而鱼类（38.3%）和介形虫处理组（24.0%）中只有很低比例的卵在第4天孵化。处理组的平均孵化时间较长，变异性较大;差异具有统计学显著性（ANOVA，P = 0.005）。相对于控制，代表一个简单的微观控制的非生物变量，治疗可以被视为相对复杂的环境，水蚤也暴露于生物线索。在这些更复杂的条件下，通过不同的孵化动力学获得相同数量的孵化。处理组的初孵仔鱼出现较晚，孵化率变化较大。这些观察结果证实了先前从实验室实验中观察到的模式，这些实验测试了竞争和波动的环境条件（光：暗，温度制度）对D。obtusa生殖和人口参数。他们也同意最近获得的证据有关的重要性，生物线索孵化的ephippial鸡蛋。总的来说，证据表明水蚤可以在休眠期间检测信息化学物质。具体而言，我们建议，在水介质中的潜在的捕食者和竞争对手的存在下，在短期孵化的ephippial蛋的孵化能力。
The beginning and end of diapause are two important transition points in cladoceran life history. The influence of environmental variables on the dynamics of these processes still deserves attention, especially as concerns the role of biotic factors. In this paper we focus on emergence from diapause, testing (1) whether ephippia of Daphnia obtusa Kurz can assess the presence in the water of typical planktivorous fish or ostracods, and (2) whether such an assessment results in changes in hatching strategy. Total number of hatchlings from D. obtusa ephippial eggs did not differ between the control and the treatments in which the presence of fish or ostracods could be detected (ANOVA, P = 0.884). However, hatching dynamics were different: most of the eggs hatched synchronously at day 4 (83.3% of the total hatchlings number) in the control, while only a low proportion of eggs hatched on day 4 in the fish (38.3%), and ostracod treatments (24.0% of the total). Mean hatching time was longer, and variability larger, in the treatments than in the control; differences resulted statistically significant (ANOVA, P = 0.005). With respect to the control, representing a simple microcosm controlled by abiotic variables only, the treatments may be regarded as relatively complex environments, in which Daphnia is also exposed to biotic cues. Under these more complex conditions, the same number of hatchlings is obtained through different hatching dynamics. In the treatments, the first hatchlings appeared later and the hatching rate was more variable than in the control. These observations confirm previously observed patterns from laboratory experiments which tested the effect of competition and fluctuating environmental conditions (light:dark, temperature regimes) on D. obtusa reproductive and demographic parameters. They are also in agreement with recently obtained evidence concerning the importance of biotic cues for hatching of ephippial eggs. Overall, the evidence suggests that Daphnia can detect infochemicals during dormancy. Specifically, we propose that the presence in the water medium of potential predators and competitors results in a short-term hatching asynchrony of ephippial eggs.