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.

Morphometric data was collected using a Microscribe.

Table of species dietary data

Dietary data based on semantic analysis of the literature. Contains 13 dietary categories for 40 canid species.

File- diet.csv

Table of Genebank accession numbers for analyzed genes

Table containing the accession number for the genes used in the dating of the phylogenetic tree. Contains genetic information for 38 canid species plus 4 outgroups.

File- genes.xls

Canidae phylogeny

Dated phylogeny used in all comparative analysis.

File- dated_canidae.tree

Average measures for each species

Mean values for each log-measurement for each species. Contain 40 measurements for 39 species.

File- means.xls

Phenotypic covariance matrix for morphometric traits

40x40 covariance P matrix for the within-group pattern of co/variation.

File- W.xlsx

Morphological vectors associated to ecological change

Diet-specific morphological changes (Δz_diet) and selection gradients (β_diet)

File- ecoV.xlsx

Factors controlled

Table containing formulas used in the linear models used to control for sources of within-species patterns of variation before calculating patterns of within-group covariance.

File- factors_.csv