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.

中文翻译：

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活ida科（食肉动物，哺乳动物）头骨的生态形态适应性进化的选择和限制。

表型与生态之间的关联对于理解形态演化的环境驱动因素至关重要。当处理复杂的特征（例如头骨）时，这是一项特别具有挑战性的任务，在头骨上会产生多种选择压力，并且进化可能会受到个体遗传​​和遗传因素的限制。我集成了形态计量学工具，比较方法和定量遗传学，以研究在现存的犬科动物头骨进化过程中，个体发育的约束和选择可能如何相互作用。结果证实，颅骨形态的变化在很大程度上是适应性的，并且受饮食组成的变化影响。尽管对自适应景观的研究揭示了两条阻力最小的主要选择线（一条与尺寸相关，另一条与功能形状特征相关），沿尺寸的演化速率高于形状尺寸，表明约束条件对形态演化的影响。结构模型分析表明，大小（这是大多数遗传/表型变异的线），可能已成为限制因素，对饮食进化产生了负面影响。在选择大型猎物时，可以通过沿大小和形状两个方向进行强力选择来克服限制。此处获得的结果表明，微进化约束可能在塑造形态进化的宏观进化模式中起作用。这是大多数遗传/表型变异的代名词，可能已成为制约因素，对饮食的演变产生了负面影响。在选择大型猎物时，可以通过沿大小和形状两个方向进行强力选择来克服限制。此处获得的结果表明，微进化约束可能在塑造形态进化的宏观进化模式中起作用。这是大多数遗传/表型变异的代名词，可能已成为制约因素，对饮食的演变产生了负面影响。在选择大型猎物时，可以通过沿大小和形状两个方向进行强力选择来克服限制。此处获得的结果表明，微进化约束可能在塑造形态进化的宏观进化模式中起作用。