Data from: Adaptive evolution in locomotor performance: how selective pressures and functional relationships produce diversity

Despite the complexity of nature, most comparative studies of phenotypic evolution consider selective pressures in isolation. When competing pressures operate on the same system, it is commonly expected that trade-offs will occur that will limit the evolution of phenotypic diversity, however, it is possible that interactions amongst selective pressures may promote diversity instead. We explored the evolution of locomotor performance in lizards in relation to possible selective pressures using the Ornstein-Uhlenbeck process. Here, we show that a combination of selection based on foraging mode and predator escape is required to explain variation in performance phenotypes. Surprisingly, habitat use contributed little explanatory power. We find that it is possible to evolve very different abilities in performance which were previously thought to be tightly correlated, supporting a growing literature that explores the many-to-one mapping of morphological design. While we generally find the expected trade-off between maximal exertion and speed, this relationship surprisingly disappears when species experience selection for both performance types. We conclude that functional integration need not limit adaptive potential, and that an integrative approach considering multiple major influences on a phenotype allows a more complete understanding of adaptation and the evolution of diversity.

尽管自然界的复杂性极高，但绝大多数针对表型进化（phenotypic evolution）的比较研究，均仅孤立地考量选择压力的作用。当多重相互竞争的选择压力作用于同一系统时，学界通常认为会出现权衡（trade-off）关系，进而限制表型多样性的进化；但实际上，选择压力间的相互作用反而可能推动多样性的演化。本研究借助奥恩斯坦-乌伦贝克过程（Ornstein-Uhlenbeck process），探究了蜥蜴类运动性能（locomotor performance）的进化与潜在选择压力的关联。研究结果显示，唯有结合基于觅食模式与避敌行为的选择压力，方能解释性能表型的变异。令人意外的是，生境利用对该变异的解释力极低。本研究发现，此前被认为紧密相关的运动性能维度，完全可演化出显著差异的能力；这一结果佐证了日益增多的、探讨形态构建（morphological design）多对一映射（many-to-one mapping）的相关研究。尽管本研究总体上观测到了预期的最大发力能力与运动速度间的权衡关系，但当物种同时面临两种性能维度的选择压力时，这一关联却意外消失。本研究最终得出结论：功能整合未必会限制物种的适应潜力；而通过整合式研究框架，同时考量对表型产生影响的多重核心因素，方能更全面地理解适应过程与多样性演化的机制。