Fuentes-Soriano , Sara .
Patterns of trait evolution within the tribe Physarieae (Brassicaceae): changes in morphology.
The mustard family (Brassicaceae) is economically important but the evolution of its morphology is not well understood. Here I re-evaluated patterns of morphological evolution in Brassicaceae and estimated ancestral trait values of eleven continuous morphological traits using the tribe Phyarieae as a model system. A three-locus data set for the tribe gathered from chloroplast and nuclear data and new methods to model directional change were used to identify the best-fitting models of evolution before ancestral character values were reconstructed using Bayesian analyses. The analyses included traits traditionally used in the systematics of Brassicaceae, such as fruits and seeds, as well as other characters frequently neglected in the study of the family, such as style length, and pollen size. Results show rather unexpectedly that levels of morphological homoplasy, as defined by values of trait phylogenetic signal, within Brassicaceae vary from being very obvious to almost absent. Modes of trait evolution were mostly consistent with a gradual model, but a few characters fit best with models of punctuated evolution (fruit width, replum shape, pollen size). Historically, rates of trait evolution were mostly constant, except for the rapid and recent evolution of replum shape, seed number, and pollen size. Fruit evolution within Physarieae reflected changes of individual components as inferred by the different rates and modes of individual trait evolution. Change in pollen size and seed number were predominantly directional. These results not only highlighted the phylogenetic potential of using continuous traits in the systematics of Brassicaceae, but also suggested that the individual components of single organs, such as fruit or seeds (e.g. length, width, size, number of parts) can evolve at different rates and modes. These results are especially relevant to understanding morphology and variation of the fruits, which is one of the most diverse and traditionally used characters in the systematics of the family.
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1 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166, USA
Bayesian comparative methods
Evolutionary trait models
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM