Host control and nutrient trading in a photosynthetic symbiosis
Host control and nutrient trading in a photosynthetic symbiosis
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DOI：
10.1016/j.jtbi.2016.02.021
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发表时间：
2016-09-21
影响因子：
2
通讯作者：
Wood, A. Jamie
中科院分区：
文献类型：
--
作者：
Dean, Andrew D.;Minter, Ewan J. A.;Wood, A. Jamie
光共生是最重要的进化轨迹之一，导致所有复杂光合生物的叶绿体和随后的发展。纤毛虫草履虫法氏囊和小球藻有一个很好的建立和研究的光依赖内共生关系。尽管它的突出，仍有许多悬而未决的问题，关于光共生的确切机制。特别有趣的是，宿主如何维持和管理其共生体负荷，以响应自身和共生体之间的营养分配。在这里，我们构建了一个详细的数学模型，从文献中参数化，明确地将营养交易纳入双方的确定性模型中。该模型展示了共生关系如何表现为共生体对宿主的寄生，互利共生，其中双方都受益，或宿主对共生体的利用。我们表明，光共生的确切性质是由环境条件（光合作用可获得多少光）和宿主对其共生负荷的控制水平决定的。我们的模型提供了一个框架，在这个框架内，有可能提出关于这个已建立的光依赖性内共生的重要例子的进化行为的详细问题；我们特别关注一个问题，即宿主控制的进化，并使用自适应动力学方法表明，在相关成本不过高的情况下，适度水平的宿主控制可能会进化。(C) 2016年作者。Elsevier Ltd.出版。
Photosymbiosis is one of the most important evolutionary trajectories, resulting in the chloroplast and the subsequent development of all complex photosynthetic organisms. The ciliate Paramecium bursaria and the alga Chlorella have a well established and well studied light dependent endosymbiotic relationship. Despite its prominence, there remain many unanswered questions regarding the exact mechanisms of the photosymbiosis. Of particular interest is how a host maintains and manages its symbiont load in response to the allocation of nutrients between itself and its symbionts. Here we construct a detailed mathematical model, parameterised from the literature, that explicitly incorporates nutrient trading within a deterministic model of both partners. The model demonstrates how the symbiotic relationship can manifest as parasitism of the host by the symbionts, mutualism, wherein both partners benefit, or exploitation of the symbionts by the hosts. We show that the precise nature of the photosymbiosis is determined by both environmental conditions (how much light is available for photosynthesis) and the level of control a host has over its symbiont load. Our model provides a framework within which it is possible to pose detailed questions regarding the evolutionary behaviour of this important example of an established light dependent endosymbiosis; we focus on one question in particular, namely the evolution of host control, and show using an adaptive dynamics approach that a moderate level of host control may evolve provided the associated costs are not prohibitive. (C) 2016 The Authors. Published by Elsevier Ltd.