Am Nat. 2020 Aug;196(2):197-215. doi: 10.1086/709610. Epub 2020 Jun 22.
The association between phenotype and ecology is essential for understanding the environmental drivers of morphological evolution. This is a particularly challenging task when dealing with complex traits, such as the skull, where multiple selective pressures are at play and evolution might be constrained by ontogenetic and genetic factors. I integrate morphometric tools, comparative methods, and quantitative genetics to investigate how ontogenetic constraints and selection might have interacted during the evolution of the skull in extant Canidae. The results confirm that the evolution of cranial morphology was largely adaptive and molded by changes in diet composition. While the investigation of the adaptive landscape reveals two main selective lines of least resistance (one associated with size and one associated with functional shape features), rates of evolution along size were higher than those found for shape dimensions, suggesting the influence of constraints on morphological evolution. Structural modeling analyses revealed that size, which is the line of most genetic/phenotypic variation, might have acted as a constraint, negatively impacting dietary evolution. Constraints might have been overcome in the case of selection for the consumption of large prey by associating strong selection along both size and shape directions. The results obtained here show that microevolutionary constraints may have played a role in shaping macroevolutionary patterns of morphological evolution.
表型与生态的关联对于理解形态进化的环境驱动因素至关重要。在处理复杂特征（如头骨）时，这是一项特别具有挑战性的任务，因为头骨受到多种选择压力的影响，并且进化可能受到个体发生和遗传因素的限制。我整合了形态计量工具、比较方法和数量遗传学，以研究在现存犬科动物的头骨进化过程中，个体发生限制和选择是如何相互作用的。研究结果证实，颅面形态的进化在很大程度上是适应性的，受饮食组成变化的影响。虽然对适应景观的研究揭示了两个主要的最小阻力选择线（一个与大小有关，另一个与功能形状特征有关），但大小沿进化的速度高于形状尺寸的进化速度，这表明限制对形态进化的影响。结构建模分析表明，大小（即遗传/表型变异的主要线）可能作为一种限制因素，对饮食进化产生负面影响。在选择大型猎物时，大小和形状方向的强烈选择可能克服了限制因素。这里得到的结果表明，微观进化限制可能在塑造宏观进化形态进化模式方面发挥了作用。
