Predicting Coexistence in Species with Continuous Ontogenetic Niche Shifts and Competitive Asymmetry
Predicting Coexistence in Species with Continuous Ontogenetic Niche Shifts and Competitive Asymmetry
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预测具有连续个体发生生态位转移和竞争不对称的物种共存
DOI：
10.1101/119446
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
T. Coulson
中科院分区：
文献类型：
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作者：
R. Bassar;J. Travis;T. Coulson
生态学中一个长期存在的问题是，结构化的生命周期是否阻碍或促进了物种之间的共存。基于生命周期中具有两个离散阶段的种群的理论表明，共存需要至少一个物种在不同阶段之间转移其生态位，并且每个物种都是其中一个生态位中更好的竞争者。然而，在许多情况下，生态位转移与生物体大小等潜在连续特征的变化有关，我们几乎没有预测这种个体发育动力学如何影响共存条件。在这里，我们开发了一个基于积分投影模型(IPMS)的物种共存分析框架，该模型结合了资源生态位和竞争能力的持续个体发育变化。我们使用来自特里尼达斯孔雀鱼的实验数据对模型进行参数化，并预测生态位的变化和竞争对称性如何允许或阻止物种共存。总体而言，我们的结果表明，竞争对适应度的影响取决于特征中介的生态位分离、特征中介的生态位部分的竞争不对称性(通过体型共享)，以及体型对体型的敏感性。当考虑到所有这三个条件时，我们发现了多种生态和进化共存的途径。当两个物种都可以随着个体大小的增加而改变其生态位，并且物种之间对资源的竞争是对称的，那么随着个体发育而将其生态位转移到更大程度的物种将竞争性地排除其他物种。当竞争能力随着体型的增加而增强时，当较好的竞争者随着体型的变化而改变其生态位的程度小于较弱的竞争者时，两个物种可以共存。随着更好的竞争对手随着规模的扩大而越来越多地改变其利基市场，这一共存区域缩小了。当两个物种都随着个体大小改变其生态位，但每个物种在较小或较大个体所使用的资源上都是更好的竞争者时，该模型预测在一定范围的生态位转变中会出现另一种稳定的状态。我们讨论了我们的结果如何为物种共存和大小结构物种间竞争的进化后果提供了新的见解。
A longstanding problem in ecology is whether structured life cycles impede or facilitate coexistence between species. Theory based on populations with two discrete stages in the life-cycle indicates that coexistence requires at least one species to shift its niche between stages and that each species is a better competitor in one of the niches. However, in many cases, niche shifts are associated with changes in an underlying continuous trait like organism size and we have few predictions for how the conditions for coexistence are affected by this type of ontogenetic dynamics. Here we develop a framework for analyzing species coexistence based on Integral Projection Models (IPMs) that incorporates continuous ontogenetic changes in both the resource niche and competitive ability. We parameterize the model using experimental data from Trinidadian guppies and make predictions about how niche shifts and competitive symmetries allow or prevent species coexistence. Overall, our results show that the effects of competition on fitness depend upon trait-mediated niche-separation, trait-mediated competitive asymmetry in the part of the niche that is shared across body sizes, and the sensitivity of fitness to body size. When all three conditions are considered, we find multiple ecological and evolutionary routes to coexistence. When both species can shift their niche with increasing body size and competition for resources among the species and sizes is symmetric, then the species that shifts its niche to a greater degree with ontogeny will competitively exclude the other species. When competitive ability increases with increasing body size, then the two species can coexist when the better competitor shifts its niche with body size to a lesser degree than the weaker competitior. This region of coexistence shrinks as the better competitor increasingly shifts its niche with increasing size. When both species shift their niches with size, but each is a better competitor on resources used by smaller or larger individuals, then the model predicts an alternative stable state over some range of niche shifts. We discuss how our results provide new insights into species coexistence and the evolutionary consequences of size-structured interspecific competition.