Institute for the Study of Complex Systems, 900 University Street, D-X, Seattle, WA, 98101, USA.
Biosystems. 2021 Jul;205:104417. doi: 10.1016/j.biosystems.2021.104417. Epub 2021 Mar 30.
Mutualistic symbiosis, we now know, is a ubiquitous phenomenon in the natural world. And, in every case, there was an initial "genesis" - a "how" process that may have been at once unique to each situation and perhaps also shared a common set of facilitators. However, a full explanation of symbiogenesis also requires an answer to the "why" question, for natural selection is a stringent economizer. Something as contrarian as mutualistic cooperation between "differently named" organisms must also provide functional advantages for the participants that will be favored by natural selection (differential survival and reproduction). Enter the "Synergism Hypothesis" - the thesis that synergistic functional effects of various kinds are a common cause of cooperative relationships of all kinds in nature, including symbioses. When different organisms have complementary capabilities that are mutually beneficial and cannot otherwise be attained, the benefits derived from symbiotic cooperation will outweigh the costs. Among the many documented cases of symbiogenesis over time, lichens provide perhaps the most familiar, well-studied example, while the eukaryotes are often cited as a game-changer. The answer to the "why" question was, in each case, determinative for symbiogenesis.
共生关系，我们现在知道，是自然界中普遍存在的现象。而且，在每种情况下，都有一个初始的“起源”-一个“如何”的过程，这个过程可能在每种情况下都是独特的，也可能有一些共同的促进因素。然而，共生关系的完整解释也需要回答“为什么”的问题，因为自然选择是一个严格的节约者。像“不同名称”的生物体之间互惠合作这样的反直觉现象，也必须为参与者提供自然选择（差异生存和繁殖）所青睐的功能优势。这就引出了“协同作用假说”-协同作用的各种功能效应是自然界中各种合作关系（包括共生关系）的共同原因。当不同的生物体具有互补的、互利的能力，而这些能力又无法单独获得时，从共生合作中获得的好处将超过成本。在共生关系随时间而发展的众多有记载的案例中，地衣可能提供了最熟悉、研究最充分的例子，而真核生物则经常被认为是一个改变游戏规则的因素。在每种情况下，“为什么”的答案对共生关系的起源都是决定性的。
