Phylogenetic Stability, Tree Shape, and Character Compatibility: A Case Study Using Early Tetrapods.
Phylogenetic tree shape varies as the evolutionary processes affecting a clade change over time. In this study, we examined an empirical phylogeny of fossil tetrapods during several time intervals, and studied how temporal constraints manifested in patterns of tree imbalance and character change. The results indicate that the impact of temporal constraints on tree shape is minimal and highlights the stability through time of the reference tetrapod phylogeny. Unexpected values of imbalance for Mississippian and Pennsylvanian time slices strongly support the hypothesis that the Carboniferous was a period of explosive tetrapod radiation. Several significant diversification shifts take place in the Mississippian and underpin increased terrestrialization among the earliest limbed vertebrates. Character incompatibility is relatively high at the beginning of tetrapod history, but quickly decreases to a relatively stable lower level, relative to a null distribution based on constant rates of character change. This implies that basal tetrapods had high, but declining, rates of homoplasy early in their evolutionary history, although the origin of Lissamphibia is an exception to this trend. The time slice approach is a powerful method of phylogenetic analysis and a useful tool for assessing the impact of combining extinct and extant taxa in phylogenetic analyses of large and speciose clades.
MUSE-Museo delle Scienze, Corso del Lavoro e della Scienza, 3, 38122 Trento, Italy; School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK; massimo.bernardi@muse.it.
Massimo
M
Bernardi
Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605-2496, USA;
Kenneth D
KD
Angielczyk
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48103, USA; and.
Jonathan S
JS
Mitchell
School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Green Lane, Lincoln LN6 7DL, UK.
Marcello
M
Ruta
D000663:Amphibians / Q000145:classification; D000818:Animals; D005075:Biological Evolution; D002965:Classification; D005580:Fossils; D049810:Genetic Speciation; D010802:Phylogeny
Character compatibility; Mesozoic; Paleozoic; diversification shifts; tetrapod terrestrialization; tree balance; tree distance.