Marinone María C, Zagarese Horacio E
Instituto Nacional de Investigación y Desarrollo Pesquero, Luis Maria Campos Igldo-8o B, 1426, Buenos Aires, Argentina.
Laboratorio de Limnología Pesquera, Alférez Parejas 125, 1107, Buenos Aires, Argentina.
Oecologia. 1991 May;86(3):372-377. doi: 10.1007/BF00317603.
We present data on polymorphism of the rotifer Keratella tropica from an outdoor, mesoscale experiment and a series of laboratory induction assays. In the outdoor experiment the biomass of planktonic crustaceans was noticeably depressed by larval fish predation, and associated with this depression K. tropica underwent a striking reduction of caudal spines. Subsequent laboratory studies showed that the positive association between crustacean biomass and caudal spine length was a cause and effect relationship. This is the first record of rotifer morphological change as an indirect effect of fish predation. In laboratory experiments filtrates of monospecific cultures of a cyclopoid copepod, a calanoid copepod and 5 cladocerans induced a remarkable spine development. Morphological induction showed a direct relationship with the concentration of crustaceans, both under field and laboratory conditions. Long spines were found to be strong deterrents against small predators (Acanthocyclops robustus copepodites), but were useless against large ones (females of the same species). The morphotypes of K. tropica obtained by experimental induction from a single clone encompass much of the worldwide variation of the species.
我们展示了来自一项室外中尺度实验和一系列实验室诱导试验的热带臂尾轮虫（Keratella tropica）多态性数据。在室外实验中，浮游甲壳类动物的生物量因幼鱼捕食而显著降低，与此相关的是，热带臂尾轮虫的尾棘明显减少。随后的实验室研究表明，甲壳类动物生物量与尾棘长度之间的正相关是一种因果关系。这是轮虫形态变化作为鱼类捕食间接效应的首次记录。在实验室实验中，一种剑水蚤、一种哲水蚤和5种枝角类单种培养物的滤液诱导了显著的棘发育。在野外和实验室条件下，形态诱导都与甲壳类动物的浓度呈直接关系。发现长棘对小型捕食者（强壮刺剑水蚤桡足幼体）有很强的威慑作用，但对大型捕食者（同一物种的雌性）则无效。通过实验诱导从单个克隆获得的热带臂尾轮虫形态型涵盖了该物种在全球范围内的大部分变异。
