American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“Selection and constraints in the ecomorphological adaptive evolution of the skull of living Canidae (Carnivora, Mammalia)”

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Fabio Andrade Machado (Aug 2020)

Evolution of cranial morphology was shaped by selection and constraints in Canidae (Carnivora)

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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. In the present contribution 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.