Weak sinks could cradle mutualistic symbioses – strong sources should harbour parasitic symbioses
Weak sinks could cradle mutualistic symbioses – strong sources should harbour parasitic symbioses
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DOI：
10.1046/j.1420-9101.2000.00157.x
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发表时间：
2000-03
影响因子：
2.1
通讯作者：
Hochberg;Gomulkiewicz;Holt;Thompson
中科院分区：
文献类型：
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作者：
Hochberg;Gomulkiewicz;Holt;Thompson
使用专性共生体和它的主机上的选择的人口模型，我们评估如何在地理景观的人口差异可以产生相互作用的物种选择马赛克。该模型假设宿主种群在地理上从人口来源到汇的共生体的影响的情况下，不同的，有毒和相对无毒的形式的共生体在所有的栖息地相互竞争。我们的研究结果表明，生产力梯度可以创建跨栖息地的选择马赛克，导致复杂的健身景观的进化发生。我们发现，相对有毒的共生体只有在它们在干扰（即竞争和/或交叉传播）相互作用方面优于无毒菌株或物种时才能持续存在。当这种权衡存在时，我们预测更具毒性的共生体最有可能出现在宿主种群增长最高的栖息地，而更具毒性的共生体应该倾向于在更边缘的栖息地甚至无共生体宿主的栖息地汇中持续存在。人口汇可能是最有可能有利于新互惠关系起源的栖息地。非常有成效的互惠可能被超级寄生者或骗子利用。我们讨论了我们的研究结果的地理情景出现的互惠，以及长期存在的争论的地理模式在维护性别。
Using a population model of selection on an obligate symbiont and its host, we evaluate how demographic differences across geographical landscapes can produce selection mosaics in interacting species. The model assumes that the host populations vary geographically from demographic sources to sinks in the absence of effects by the symbionts, and that a virulent and a relatively avirulent form of the symbiont compete with one another across all habitats. Our results indicate that productivity gradients can create selection mosaics across habitats, resulting in complex fitness landscapes over which evolution occurs. We find that relatively virulent symbionts only persist if they have an advantage over avirulent strains or species in terms of interference (i.e. competition, and/or cross‐transmission) interactions. When such a trade‐off exists, we predict that the more virulent symbiont is most likely to be found in habitats where host population growth is highest, whereas the more avirulent symbiont should tend to persist in more marginal habitats or even habitat sinks for symbiont‐free hosts. Demographic sinks may be the habitats most likely to favour the origin of new mutualisms. Very productive mutualisms can be exploited by hyperparasites or cheaters. We discuss our findings in terms of geographical scenarios for the emergence of mutualisms, and the long‐standing debate about geographical patterns in the maintenance of sex.