Skull morphological integration and evolution of skull morphology in Feliformia (Carnivora: Mammalia)

Author(s)

Thiago Macek Gonçalves Zahn

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências
• Defense date: 15 ago. 2016

Examining board members

Gabriel Henrique Marroig Zambonato; José Alexandre Felizola Diniz Filho; Pedro Cordeiro Estrela de Andrade Pinto

• Advisor: Gabriel Henrique Marroig Zambonato

Abstract

Morphological integration determines the standing variation available within a lineage in different directions of the multivariate space of a trait set, and can therefore have important evolutionary consequences, biasing the direction and rate of morphological evolution in certain directions. Consequently, studying the evolution of morphological integration is important to understand a lineage\'s phenotypic evolution. Here I employ a comparative quantitative genetic framework to study the evolution of morphological integration in the skull for the suborder Feliformia (Carnivora), a group with remarkable phylogenetic, morphological and ecological diversity for which previous analysis of integration included a limited number of species. To this purpose, I compare within-population phenotypic covariance matrices quantifying the associations between 35 skull linear measurements in a set of taxa including all seven feliform families and over one third of the suborder\'s extant phylogenetic diversity. I also assess the association between morphological integration and the evolution of average skull morphology, as well as the influence of evolutionary history (phylogeny) and two ecological aspects (diet and sociality) on the evolution of average morphology and integration. Skull integration patterns (i.e. which characters covary the most) are quite stable in the suborder, as seen among other mammals, but also have some structuring between groups, with relatively distinct patterns in Felidae, Hyaenidae and Prionodontidae. Integration magnitudes are also relatively structured, with generally higher values in Felidae and consistently lower values in Hyaenidae. Nevertheless, the overall magnitude of integration is evolutionarily labile, as in other mammals, with important variations occurring within each family. I found a general association between the evolution of average morphology and changes in integration patterns and magnitudes for the suborder as a whole and also for many less inclusive groups, which in some cases leads to similar integration between morphologically convergent, but phylogenetically distant taxa. The evolution of integration patterns is correlated to phylogenetic history in Feliformia as a whole and in most groups above, but none below the family level, corroborating relatively distinct covariation patterns in spite of their high similarity, and also a greater constraint of integration within each family. Diet is associated to phylogeny, and correlates to the evolution of average morphology and integration patterns in the suborder before, but not after correction for phylogenetic relatedness, indicating that dietary changes are part of the shared evolutionary history which shaped the differences in average morphology and integration existing in the group. The characters with covariation patterns more closely associated to diet include parts of the oral and zygomatic skull regions, as well as parts of the neurocranium. Sociality is related to the evolution of average skull morphology, but not to general integration patterns in Feliformia as a whole, although there are correlations between sociality and the selection response patterns of some specific characters, including parts of the neurocranium and measurements related to the zygomatic arch. Mongooses (family Herpestidae) had the evolution of their average skull morphology and integration patterns significantly influenced by both diet and sociality, stressing the importance of these two ecological factors for phenotypic evolution of this group and showing for the first time a direct association between morphological integration in the skull and social behaviour, possibly mediated by aspects related to brain development. The present work thus suggests a complex interaction of factors affecting the evolution of skull morphology in Feliformia, and opens up directions for future work, including analyses of skull modularity patterns in this group and, possibly, comparative analyses of different hypercarnivore morphotypes addressing average skull morphology and morphological integration, as well as diet and possibly other factors (AU)

• FAPESP's process: 13/07299-1 - Skull morphological integration and evolution of cranial morphology in Feliformia (Carnivora; Mammalia)
• Grantee: Thiago Macek Gonçalves Zahn
• Support type: Scholarships in Brazil - Master