Division of Plant Science, University of Dundee at SCRI, Invergowrie, Dundee DD2 5DA, UK.
J Exp Bot. 2009;60(14):3975-87. doi: 10.1093/jxb/erp282. Epub 2009 Sep 18.
Darwin performed innovative observational and experimental work on the apparently paradoxical occurrence of carnivory in photosynthetic flowering plants. The nutritional use of particulate organic material which also supplies other elements is now known to be widespread in free-living algae as well as in organisms with endosymbiotic algae and with kleptoplastids. In addition to this direct nutritional role, phagotrophy, in the broad sense of internalization of photosynthetic organisms by a eukaryote, is essential for the occurrence of present-day endosymbiotic algae and kleptoplastid-containing protists, and was essential for the origin of plastids themselves. The endosymbiotic phenomena involving photosynthetic organisms clearly played a major role in combining genomes providing different metabolic functions, but, in our opinion, this does not demand a re-appraisal of evolution by natural selection. That the balance of physiological optimization for competition for resources and minimization of losses (e.g. through predation) is a fine one, and thus subject to a complex selective process, is illustrated by the diversity of mixotrophic strategies in extant phytoplankton.
达尔文对光合作用的开花植物中明显矛盾的肉食现象进行了创新的观察和实验工作。现在已知，营养物质对颗粒有机物质的利用，也为自由生活的藻类以及具有内共生藻类和偷取质体的生物提供了其他元素。除了这种直接的营养作用之外，广义上的吞噬作用（真核生物内化光合作用生物）对于现今内共生藻类和含有偷取质体的原生生物的发生至关重要，对于质体本身的起源也至关重要。涉及光合作用生物的内共生现象显然在结合提供不同代谢功能的基因组方面发挥了重要作用，但在我们看来，这并不需要重新评估自然选择的进化。对于资源竞争的生理优化平衡和损失最小化（例如通过捕食）的要求非常高，因此受到复杂的选择过程的影响，这一点可以通过现存浮游植物的混合营养策略的多样性得到说明。
