Institute of Evolution, Centre for Ecological Research, Konkoly-Thege M. út 29-33, Budapest 1121, Hungary; Doctoral School of Biology, Institute of Biology, Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest 1117, Hungary.
Institute of Evolution, Centre for Ecological Research, Konkoly-Thege M. út 29-33, Budapest 1121, Hungary; Centre for Eco-Epidemiology, National Laboratory for Health Security, Hungary.
J Theor Biol. 2024 Jan 7;576:111620. doi: 10.1016/j.jtbi.2023.111620. Epub 2023 Sep 13.
The coevolution of hosts and symbionts based on virulence and mode of transmission is a complex and diverse biological phenomenon. We introduced a conceptual model to study the stable coexistence and coevolution of an obligate symbiont (mutualist or parasite) with mixed-mode transmission and its host. Using an age-structured Leslie model for the host, we demonstrated how the obligate symbiont could modify the host's life history traits (survival and fecundity) and the long-term growth rate of the infected lineage. When the symbiont is vertically transmitted, we found that the host and its symbiont could maximize the infected lineage's evolutionary success (multi-level selection). Our model showed that symbionts' effect on host longevity and reproduction might differ, even be opposing, and their net effect might often be counterintuitive. The evolutionary stability of the ecologically stable coexistence was analyzed in the framework of coevolutionary dynamics. Moreover, we found conditions for the ecological and evolutionary stability of the resident host-symbiont pair, which does not allow invasion by rare mutants (each mutant dies out by ecological selection). We concluded that, within the context of our simplified model conditions, a host-symbiont system with mixed-mode transmission is evolutionarily stable unconditionally only if the host can maximize the Malthusian parameters of the infected and non-infected lineages using the same strategy. Finally, we performed a game-theoretical analysis of our selection situation and compared two stability definitions.
基于毒力和传播方式的宿主和共生体的共同进化是一种复杂多样的生物学现象。我们引入了一个概念模型来研究具有混合传播方式的专性共生体（互利共生或寄生虫）与其宿主的稳定共存和共同进化。我们使用宿主的年龄结构 Leslie 模型，展示了专性共生体如何改变宿主的生活史特征（存活和繁殖力）以及受感染谱系的长期增长率。当共生体垂直传播时，我们发现宿主和共生体可以使受感染谱系的进化成功最大化（多层次选择）。我们的模型表明，共生体对宿主寿命和繁殖力的影响可能不同，甚至相反，它们的净效应通常可能违反直觉。我们在共进化动力学的框架内分析了生态稳定共存的进化稳定性。此外，我们发现了驻留宿主-共生体对的生态和进化稳定性的条件，即稀有突变体（每个突变体因生态选择而灭绝）不能入侵。我们的结论是，在我们简化模型条件的背景下，具有混合传播方式的宿主-共生体系统只有在宿主能够使用相同策略使感染和未感染谱系的马尔萨斯参数最大化的情况下，才无条件地具有进化稳定性。最后，我们对我们的选择情况进行了博弈论分析，并比较了两种稳定性定义。
