Among the major unresolved questions in ecosystem evolution are whether coevolving multispecies communities are dominated more by biotic or by abiotic factors, and whether evolutionary stasis affects performance as well as ecological profile; these issues remain difficult to address experimentally. Digital evolution, a computer-based instantiation of Darwinian evolution in which short self-replicating computer programs compete, mutate, and evolve, is an excellent platform for investigating such topics in a rigorous experimental manner. We evolved model communities with ecological interdependence among community members, which were subjected to two principal types of mass extinction: a pulse extinction that killed randomly, and a selective press extinction involving an alteration of the abiotic environment to which the communities had to adapt. These treatments were applied at two different strengths (Strong and Weak), along with unperturbed Control experiments. We performed several kinds of competition experiments using simplified versions of these communities to see whether long-term stability that was implied previously by ecological and phylogenetic metrics was also reflected in performance, namely, whether fitness was static over long periods of time. Results from Control and Weak treatment communities revealed almost completely transitive evolution, while Strong treatment communities showed higher incidences of temporal intransitivity, with pre-treatment ecotypes often able to displace some of their post-recovery successors. However, pre-treatment carryovers more often had lower fitness in mixed communities than in their own fully native conditions. Replacement and invasion experiments pitting single ecotypes against pre-treatment reference communities showed that many of the invading ecotypes could measurably alter the fitnesses of one or more residents, usually with depressive effects, and that the strength of these effects increased over time even in the most stable communities. However, invaders taken from Strong treatment communities often had little or no effect on resident performance. While we detected periods of time when the fitness of a particular evolving ecotype remained static, this stasis was not permanent and never affected an entire community at once. Our results lend support to the fitness-deterioration interpretation of the Red Queen hypothesis, and highlight community context dependence in determining fitness, the shaping of communities by both biotic factors and abiotic forcing, and the illusory nature of evolutionary stasis. Our results also demonstrate the potential of digital evolution studies to illuminate many aspects of evolution in interacting multispecies communities.

中文翻译：

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时移实验中（频率相关）适应度的改变揭示了虚拟侏罗纪公园中的隐秘协同进化和不协调停滞

生态系统进化中未解决的主要问题包括共同进化的多物种群落是否更多地由生物或非生物因素主导，以及进化停滞是否影响性能和生态特征；这些问题仍然难以通过实验解决。数字进化是达尔文进化的基于计算机的实例化，其中简短的自我复制计算机程序竞争、变异和进化，是以严格的实验方式研究此类主题的绝佳平台。我们进化出社区成员之间具有生态相互依存关系的模型社区，这些社区受到两种主要类型的大规模灭绝：随机杀死的脉冲灭绝和涉及社区必须适应的非生物环境改变的选择性新闻灭绝。这些处理以两种不同的强度（强和弱）以及未受干扰的对照实验应用。我们使用这些社区的简化版本进行了几种竞争实验，以查看先前由生态和系统发育指标暗示的长期稳定性是否也反映在性能中，即适应度是否在很长一段时间内是静态的。控制和弱处理社区的结果显示几乎完全传递进化，而强处理社区显示出更高的时间不传递性发生率，预处理生态型通常能够取代一些恢复后的继任者。然而，在混合社区中，预处理遗留物的适应性比在其完全原生条件下的适应性要低。将单一生态型与预处理参考群落进行比较的替代和入侵实验表明，许多入侵生态型可以显着改变一个或多个居民的健康状况，通常具有抑郁效应，并且这些效应的强度随着时间的推移而增加，即使在最稳定的社区。然而，来自强治疗社区的入侵者通常对居民表现几乎没有影响。虽然我们检测到特定进化生态型的适应度保持静态的时间段，但这种停滞不是永久性的，也不会立即影响整个社区。我们的结果支持了红皇后假说的适应度恶化解释，并强调了确定适应度时的社区环境依赖性，生物因素和非生物强迫对群落的塑造，以及进化停滞的虚幻本质。我们的结果还证明了数字进化研究的潜力，可以阐明相互作用的多物种社区中进化的许多方面。