Sakwińska Olga
Zoology Institute, University of Basel, Rheinsprung 9, 4051, Basel, Switzerland.
Department of Biology, Ecology and Evolution, University of Fribourg, Chemin du Museé 10, 1700, Fribourg, Switzerland.
Oecologia. 2002 May;131(3):409-417. doi: 10.1007/s00442-002-0901-0. Epub 2002 May 1.
The aim of the present study was to clarify the mechanisms underlying the expression of phenotypic plasticity in Daphnia life history traits in response to fish kairomone and to explore how these mechanisms interact with genetic variation for life history traits. I studied the effect of fish kairomone on life history traits in 16 Daphnia galeata clones. Maturation occurred more often at the earlier instars in response to the fish treatment, resulting in earlier age and smaller size at maturity. The changes in age and size at maturity which occurred in the response to the fish treatment could be attributed to a large extent to this shift. In addition, fish kairomone resulted in smaller instar increments after the maturation process was initiated, but not during the juvenile period. Within groups of animals maturing at the same instar, larger size at birth resulted in larger size at maturity, but had no effect on age at maturity. However, larger size at birth brought about earlier maturity because animals which were larger at birth matured more often at the earlier instar. Fish treatment resulted in more, but smaller, offspring in the first clutch relative to the size of the mother. Genetic variation was found in all measured life history traits. Genetic variation in plasticities of life history traits was not detectable by standard methods, and was only shown when the above mechanisms of expression of life history traits were taken into account. This study illustrates the importance of a thorough understanding of the mechanisms underlying the expression of life history traits, in this case, sources and consequences of maturation in the multiple instars. Not only is this necessary to predict the long-term effect of the environment, but also to understand the response of life history traits and their plasticities to natural selection. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00442-002-0901-0.
本研究的目的是阐明水蚤生活史特征表型可塑性表达背后的机制，以响应鱼类信息素，并探索这些机制如何与生活史特征的遗传变异相互作用。我研究了鱼类信息素对16个盔形溞克隆体生活史特征的影响。与接受鱼类处理的情况相比，早熟现象在更早的龄期更为频繁地出现，导致成熟时年龄更小、体型更小。对鱼类处理做出反应时成熟年龄和体型的变化在很大程度上可归因于这种转变。此外，鱼类信息素在成熟过程开始后导致龄期增长变小，但在幼年期则不然。在同一龄期成熟的动物群体中，出生时体型较大导致成熟时体型较大，但对成熟年龄没有影响。然而，出生时体型较大导致早熟，因为出生时体型较大的动物在更早的龄期成熟的频率更高。相对于母体大小，鱼类处理导致首次产卵时的后代数量更多但个体更小。在所有测量的生活史特征中均发现了遗传变异。生活史特征可塑性的遗传变异用标准方法无法检测到，只有在考虑到上述生活史特征表达机制时才会显现出来。本研究说明了全面理解生活史特征表达背后机制的重要性，在这种情况下，是多龄期成熟的来源和后果。这不仅对于预测环境的长期影响是必要的，而且对于理解生活史特征及其可塑性对自然选择的反应也是必要的。本文的电子补充材料可通过位于http://dx.doi.org/10.1007/s00442-002-0901-0的Springer LINK服务器获取。
