McCormick M I
Department of Marine Biology, James Cook University, Townsville, Queensland 4811, Australia e-mail:
Oecologia. 1999 Mar;118(4):412-422. doi: 10.1007/s004420050743.
Maternal hormones can play an important role in the development of fish larvae. Levels of the stress hormone, cortisol, in females are elevated by social interactions and transferred directly to the yolk of eggs, where they may influence developmental rates. In some vertebrates, prenatal exposure to high levels of testosterone determine early growth rates, social status and reproductive success. The present study examined whether post-fertilization exposure of eggs of the tropical damselfish, Pomacentrus amboinensis (Pomacentridae), to natural levels of cortisol or testosterone directly affects larval morphology at hatching. Maternal and egg levels of cortisol and testosterone varied widely among clutches of eggs from local populations around Lizard Island on the Great Barrier Reef. The morphology of larvae produced by these local fish populations also varied widely and differed significantly among sites (e.g., standard length: 2.6-3.4 mm; yolk sac area: 0.01-0.13 × 10 mm). Laboratory experiments showed that elevated cortisol levels in the egg reduced larval length at hatching, while slight elevations in testosterone increased yolk sac size. The influence of testosterone, and to a smaller extent cortisol, on larval morphology differed among egg clutches. These differences were partly explained by differences in initial egg hormone levels. Morphological changes induced by experimental hormonal regimes encompassed the entire range of variability in body attributes found in field populations. It is unclear whether cortisol influences growth alone or development rate or both. Testosterone appears to influence yolk utilization rates, and has no significant effect on growth, in contrast to its role in later developmental stages. Maternally derived cortisol and testosterone are important in regulating growth, development, and nutritive reserves of the embryo and larvae of this fish species. Factors that influence the maternal levels of cortisol and testosterone may have a major impact on larval mortality schedules and, therefore, on which breeding individuals contribute to the next generation.
母体激素在鱼类幼体发育中可发挥重要作用。社交互动会使雌性体内应激激素皮质醇水平升高，该激素会直接转移至卵黄中，进而可能影响发育速度。在一些脊椎动物中，产前接触高水平睾酮会决定早期生长速度、社会地位和繁殖成功率。本研究探究了热带雀鲷（双锯鱼科的安汶双锯鱼）的卵在受精后接触自然水平的皮质醇或睾酮是否会直接影响孵化时幼体的形态。大堡礁蜥蜴岛周边当地种群的卵块中，皮质醇和睾酮的母体及卵水平差异很大。这些当地鱼类种群产出的幼体形态差异也很大，且不同地点之间存在显著差异（例如，标准体长：2.6 - 3.4毫米；卵黄囊面积：0.01 - 0.13×10平方毫米）。实验室实验表明，卵中皮质醇水平升高会降低孵化时幼体的体长，而睾酮水平略有升高则会增加卵黄囊大小。睾酮以及在较小程度上皮质醇对幼体形态的影响在不同卵块之间存在差异。这些差异部分可由初始卵激素水平的差异来解释。实验激素处理引起的形态变化涵盖了野外种群中发现的身体特征的整个变异范围。目前尚不清楚皮质醇是单独影响生长还是发育速度，亦或是两者都有影响。与它在后期发育阶段的作用相反，睾酮似乎会影响卵黄利用率，而对生长没有显著影响。母体来源的皮质醇和睾酮在调节该鱼类物种胚胎和幼体的生长、发育及营养储备方面很重要。影响母体皮质醇和睾酮水平 的因素可能会对幼体死亡率产生重大影响，进而影响哪些繁殖个体对下一代有贡献。
