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Abstract Detail


Magallon, Susana [1], Sánchez Reyes, Luna L. [2], Gómez-Acevedo, Sandra L. [3], Hernández-Hernández, Tania [4].

Major diversification shifts through angiosperm evolutionary history.

Angiosperms represent an exceptional evolutionary radiation, yet little is understood about the dynamics, timing and drivers associated with their diversification. They are characterized by numerous morphological and functional innovations, however, previous work suggests that angiosperm-level synapomorphies are not linked with increased phylogenetic branching, but rather, that independent lineages are characterized by unexpectedly high species-richness. Several studies have evaluated the relationship between particular attributes, for example, an herbaceous life form, zygomorphic flowers, whole genome duplications, or the occupation of particular geographic areas, and increased rates of diversification. In this study, we take a complementary approach to attribute-centered studies, and investigate the placement and timing of major diversification shifts through angiosperm evolution. Our study is based on a phylogenetic tree containing 792 species representing 87% of angiosperm families, which was time-calibrated combining relaxed molecular clocks and 137 critically evaluated fossil constraints. We conducted Bayesian analyses with BAMM to identify strongly supported diversification shift configurations involving the number, placement and timing of shifts across the evolutionary tree. Because of the large number of model parameters to be estimated, the 95% credible set of distinct shift configurations is very large. Nevertheless, the shift configurations with the highest posterior probability (PP), including the one with the highest overall PP, as well as the shift configuration that maximizes the marginal probability of rate shifts (MSC), congruently identify a set of seventeen significant rate shifts across the angiosperm phylogenetic tree. The identified shifts document a variety of patterns, temporal distribution, diversification dynamics, and potential biological attributes associated with major diversification increases. Some characterize massive clades, whereas others characterize circumscribed clades within families. Two clades that contain a vast proportion of angiosperm species display dramatically different diversification patterns. Diversification shifts are differentially characterized by increasing speciation or decreasing extinction. Clades that underwent increased diversification display a vast diversity of attributes including herbaceous habit, fused corollas, zygomorphy, inflorescences that resemble large actinomorphic flowers, and adaptation to particular environments, which alone or in combination, may be linked to increased diversification. Our results provide an angiosperm-wide evolutionary perspective of the diversification history of the group. They represent an integrative framework to rigorously evaluate angiosperm diversification history, in which complex character combinations, placed in particular environmental conditions, rather than the presence of an isolated attribute, are recognized as associated with diversification rates underlying high species richness.

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1 - Universidad Nacional Autonoma de Mexico, Instituto de Biologia, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City, 04510, Mexico
2 - Universidad Nacional Autónoma de México, Posgrado en Ciencias Biológicas, Instituto de Biología, 3er Circuito de Ciudad Universitaria, Del. Coyoacán, Mexico City, DF, 04510, Mexico
3 - Universidad Nacional Autónoma de México, 3er Circuito de Ciudad Universitaria, Del. Coyoacán, Mexico City, DF, 04510, Mexico
4 - Instituto de Ecología, A.C., Departamento de Biología Evolutiva, Xalapa, Ver, Mexico

fossil record
Species richness.

Presentation Type: Oral Paper:Papers for Topics
Session: 3
Location: Salon 3/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 9:00 AM
Number: 3005
Abstract ID:594
Candidate for Awards:None

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