title: Multiple morphological clocks and total-evidence tip-dating in mammals.
abstract: Morphological integration predicts that correlated characters will coevolve; thus, each distinct suite of correlated characters might be expected to evolve according to a separate clock or 'pacemaker'. Characters in a large morphological dataset for mammals were found to be evolving according to seven separate clocks, each distinct from the molecular clock. Total-evidence tip-dating using these multiple clocks inflated divergence time estimates, but potentially improved topological inference. In particular, single-clock analyses placed several meridiungulates and condylarths in a heterodox position as stem placentals, but multi-clock analyses retrieved a more plausible and orthodox position within crown placentals. Several shortcomings (including uneven character sampling) currently impact upon the accuracy of total-evidence dating, but this study suggests that when sufficiently large and appropriately constructed phenotypic datasets become more commonplace, multi-clock approaches are feasible and can affect both divergence dates and phylogenetic relationships.
authors.affiliation: Earth Sciences Section, South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia mike.lee@samuseum.sa.gov.au.
authors.forename: Michael S Y
authors.identifier: 0000-0002-3905-0887
authors.initials: MS
authors.lastname: Lee
mesh_terms: D000818:Animals; D066264:Datasets as Topic; D019143:Evolution, Molecular; D005580:Fossils; D008322:Mammals / Q000145:classification / Q000235:genetics*; D008957:Models, Genetic; D010802:Phylogeny
keywords: Bayesian phylogenetics; Mammalia; morphological integration; relaxed clocks; tip-dating; total-evidence dating