The loss of biodiversity is altering the structure of ecological networks; however, we are currently in a poor position to predict how these altered communities will affect the evolution of remaining populations. Theory on fitness landscapes provides a framework for predicting how selection alters the evolutionary trajectory and adaptive potential of populations, but often treats the network of interacting populations as a “black box.” Here, we integrate ecological networks and fitness landscapes to examine how changes in food‐web structure shape phenotypic evolution. We conducted a field experiment that removed a guild of larval parasitoids that imposed direct and indirect selection pressures on an insect herbivore. We then measured herbivore survival as a function of three key phenotypic traits to estimate directional, quadratic, and correlational selection gradients in each treatment. We used these selection gradients to characterize the slope and curvature of the fitness landscape to understand the direct and indirect effects of consumer loss on phenotypic evolution. We found that the number of traits under directional selection increased with the removal of larval parasitoids, indicating evolution was more constrained toward a specific combination of traits. Similarly, we found that the removal of larval parasitoids altered the curvature of the fitness landscape in such a way that tended to decrease the evolvability of the traits we measured in the next generation. Our results suggest that the loss of trophic interactions can impose greater constraints on phenotypic evolution. This indicates that the simplification of ecological communities may constrain the adaptive potential of remaining populations to future environmental change.

中文翻译：

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消费者的流失限制了最终食物网的表型进化

生物多样性的丧失正在改变生态网络的结构；但是，我们目前无法预测这些改变的社区将如何影响剩余人口的演变。适应性景观理论为预测选择如何改变种群的进化轨迹和适应潜力提供了一个框架，但通常将相互作用的种群网络视为“黑匣子”。在这里，我们整合了生态网络和健身景观，以研究食物网结构的变化如何塑造表型演变。我们进行了一项野外实验，去除了对昆虫食草动物施加直接和间接选择压力的幼虫寄生虫行会。然后，我们将草食动物的生存率作为三个关键表型特征的函数进行了测量，以估算方向性，二次方，每种处理中的相关选择梯度。我们使用这些选择梯度来表征健身景观的坡度和曲率，以了解消费者流失对表型演变的直接和间接影响。我们发现，定向选择下性状的数量随着幼虫寄生虫的去除而增加，这表明进化更受特定性状组合的限制。同样，我们发现幼虫寄生虫的去除改变了健身景观的曲率，从而降低了我们在下一代中测量的性状的可进化性。我们的结果表明，营养相互作用的丧失可以对表型进化施加更大的限制。