Does the skull carry a phylogenetic signal? Evolution and modularity in the guenons

Abstract

Form and genes often tell different stories about the evolution of animals, with molecular data generally considered to be more objective than morphological data. However, form provides the basis for the description of organisms, and the study of fossils crucially depends on morphology. Complex organisms tend to evolve as 'mosaics', in which parts may be modified at varying rates and in response to different selective pressures. Thus, individual anatomical regions may contain different phylogenetic signals. In the present study, we used computerized methods to 'dissect' the skulls of a primate clade, the guenons, into functional and developmental modules (FDM). The potential of different modules as proxies for phylogenetic divergence in modern lineages was investigated. We found that the chondrocranium was the only FDM in which shape consistently had a strong and significant phylogenetic signal. This region might be less susceptible to epigenetic factors and thus more informative about phylogeny. The examination of the topology of trees from the chondrocranium suggested that the main differences evolved at the time of the radiation of terrestrial and arboreal guenons. However, phylogenetic reconstructions were found to be strongly affected by sampling error, with more localized anatomical regions (i.e. smaller/less complex FDMs) generally producing less reproducible tree topologies. This finding, if confirmed in other groups, implies that the utility of specific FDMs for phylogenetic inference could, in many cases, be hampered by the low reproducibility of results. The study also suggested that uncertainties due to sampling error may be larger than those from character sampling. This might have implications for phylogenetic analyses, which typically provide estimates of support of tree nodes based on characters but do not generally take into account the effect of sampling error on the tree topology. Nonetheless, studies of the potential of different FDMs as proxies for phylogenetic divergence in modern lineages, such as the present study, provide a framework that may help in modelling the morphological evolution of present and fossil species. (C) 2008 The Linnean Society of London

Diversification of the pectoral fin shape in damselfishes (Perciformes, Pomacentridae) of the Eastern Pacific

“…The behavioral data were summarized in a cluster analysis using an UPGMA algorithm, which allowed for determining various behavioral groups (see results). The goodness of fit of the cluster analysis was measured by the coefficient of cophenetic correlation (Cardini and Elton 2008).…”

The relative correspondence of cranial and genetic distances in papionin taxa and the impact of allometric adjustments

“…Among guenons, the basicranium was found to be the cranial region that produced phenotypic patterns most highly correlated with the published consensus phylogeny. However, differences in basicranial morphology among taxa did not contain the degree of resolution necessary to reconstruct the precise topology of the consensus phylogenetic tree (Cardini and Elton, 2008). In addition, the face, dermatocranium, and neurocranium all yielded matrices that were also significantly correlated with the genetic distance matrix (Cardini and Elton, 2008).…”

“…In guenons, the morphology of several masticatory regions, the mandible, oral cavity, and zygomatic region, all yielded morphological matrices significantly correlated with genetic distances among taxa, but the non-masticatory chondrocranium did so with a higher correlation coefficient (Cardini and Elton, 2008). Therefore, despite the intuitive link between masticatory strain, plasticity, and homoplasy, the relationship between these factors is complex, and this phenomenon does not necessarily negatively affect the correspondence between cranial morphology and genetic patterns (von Cramon-Taubadel, 2009b;Roseman et al, 2010).…”

“…Several subsequent studies have also revealed that different subsets of cranial data differ in their correspondence with genetic distances in human populations (Roseman, 2004;Harvati and Weaver, 2006;Smith, 2009;von Cramon-Taubadel, 2009a;2011b;a), guenons (Cardini and Elton 2008) and hominoid taxa (von Cramon-Taubadel and Smith, 2012). These findings highlight the importance of understanding the evolutionary basis for patterns of cranial variation across extant primate clades before they are extrapolated into the fossil record.…”

“…The phylogenetic utility of basicranial shape has also been tested in several cercopithecoid species (Cardini and Elton, 2008;Gilbert, 2011). Among guenons, the basicranium was found to be the cranial region that produced phenotypic patterns most highly correlated with the published consensus phylogeny.…”