Wimberger Peter H
Section of Ecology and Systematics, Corson Hall, Cornell University, Ithaca, NY, 14853, USA.
Evolution. 1991 Nov;45(7):1545-1563. doi: 10.1111/j.1558-5646.1991.tb02662.x.
I examined plasticity of jaw and skull morphology induced by feeding different diets in two species of the neotropical cichlid genus Geophagus. The two species possess different modes of development, which affect the size at which young begin feeding. I hypothesized that the difference in size at first feeding could lead to a difference in the amount of change inducible in the two species. The young of the substrate-spawning species, G. brasiliensis, which begin feeding at a smaller size, were predicted to be more plastic than those of the mouthbrooding species, G. steindachneri. The two diets used to induce differences were brine shrimp nauplii and chironomid larvae. Numerous measures of the jaw and skull differed significantly between groups fed the two diets but the amount of plasticity induced was small and would not present a problem for taxonomists. Contrary to my prediction, both the magnitude and pattern of plasticity induced in the two species was similar. Thus, mode of parental care and the size at which young begin feeding do not affect the degree of plasticity. Fish fed brine shrimp nauplii were longer in oral jaw region, but were shorter and shallower in the area behind the oral jaws. An additional group of G. brasiliensis was fed flake food to compare the results of this study to other studies. The differences in measures between fish fed brine shrimp diets and flake food diets were greater than those between fish fed brine shrimp and chironomid larvae. A possible role of plasticity for enhancing rather than retarding morphological evolution is discussed.
我研究了新热带丽鱼科丽体鱼属两种鱼类在投喂不同食物时，颌骨和头骨形态的可塑性。这两个物种具有不同的发育模式，这会影响幼鱼开始摄食时的大小。我推测，首次摄食时的大小差异可能导致这两个物种可诱导变化量的差异。基质产卵物种巴西丽体鱼的幼鱼开始摄食时体型较小，预计它们比口孵物种施氏丽体鱼的幼鱼更具可塑性。用于诱导差异的两种食物是卤虫无节幼体和摇蚊幼虫。在投喂两种食物的组之间，颌骨和头骨的许多测量值存在显著差异，但诱导的可塑性程度较小，不会给分类学家带来问题。与我的预测相反，两个物种诱导的可塑性大小和模式相似。因此，亲代抚育方式和幼鱼开始摄食时的大小不会影响可塑性程度。投喂卤虫无节幼体的鱼口腔颌骨区域较长，但口腔颌骨后面的区域较短且较浅。另外一组巴西丽体鱼投喂片状食物，以便将本研究结果与其他研究进行比较。投喂卤虫食物和片状食物的鱼之间测量值的差异大于投喂卤虫和摇蚊幼虫的鱼之间的差异。本文还讨论了可塑性在促进而非阻碍形态进化方面可能发挥的作用。
