Abstract Detail

Empirical Approaches to Phylogenetic Comparative Methods in Plant Science

Magallón, Susana [1], Sanchez-Reyes , Luna Luisa [2], Gómez-Acevedo, Sandra Luz [3], Hernández-Hernández, Tania [4].

A metacalibrated diversification analysis of flowering plants.

Flowering plants (Angiospermae) include an extraordinary richness, morphological diversity, and play fundamental structural and trophic roles in modern terrestrial ecosystems. Estimates on the timing of angiosperm diversification are incongruent: molecular estimates are different from each other, and most are substantially older than the Early Cretaceous oldest angiosperms fossils. Angiosperms are characterized by many unique reproductive and vegetative innovations. However, previous works indicate that the clues to angiosperm success do not lie directly on their innovations, but presumbaly on further ellaborations deployed in particular ecological or environmental contexts, which drove independent radiations. A variety of factors have been linked with angiosperm diversity, including intrinsic attributes, ecological interactions, and responses to extrinsic physical conditions. In this study, we investigate angiosperm diversification in the context of a metacalibrated timetree. A maximum likelihood phylogram, derived from sequences of three plastid and two nuclear markers and including placeholders for 87% of angiosperm families, was dated with penalized likelihood and the uncorrelated lognormal method. A thorough literature-based review of the angiosperm fossil record yielded a data base from which fossils that reliably represent the oldest record of well-supported clades were selected, spanning from genera to orders. The selected fossils were implemented as conservative minimum age constraints to particular nodes in the tree. The angiosperm crown age was bound within a 95% confidence interval obtained with a method derived from quantitative paleobiology that considers the age of the oldest fossil of the group, and the number of branches in the phylogeny that occur in the fossil record. The two relaxed clock methods yielded similar ages across the tree, but those from penalized likelihood are usually older. There is greater age variability in regions of the tree where calibration density is low. The origins of angiosperm families span from the Hauterivian (Early Cretaceous) to the Miocene (Neogene), with peaks in the Cenomanian, Campanian, Paleocene and Early Eocene. Based on the timetree, we conducted a diversification analysis to identify significant diversification shifts across angiosperms, with their estimated rates of diversification and turnover. Our results explicitly document that extant angiosperm species-richness and its distribution is the product of several non-synchronous radiations and depletions in independent lineages, which responded to different diversification dynamics in terms of the underlying rates speciation and extinction; and are associated with a variety of potential intrinsic, ecological and extrinsic drivers.

1 - Instituto De Biologia, Universidad Nacional Autonoma De Mexico, 3er Circuito De Ciudad Universitaria, Del. Coyoacan, A.P. 70-233, Mexico City, Mexico D.F., N/A, 04510, Mexico
2 - Instituto de Biología, UNAM, Departamento de Botánica, 3er Circuito de Ciudad Universitaria, Delegación Coyoacán, Mexico City, DF, 04510, Mexico
3 - Universidad Nacional Autónoma de México, Instituto de Biología, Circuito Exterior, Ciudad Universitaria, Mexico City, 04510, Mexico
4 - Instituto De Ecología, A.C., Biología Evolutiva, Km. 2.5 Carretera Antigua A Coatepec 351, Congregación El Haya, Xalapa, N/A, 91070, Mexico

Keywords:
fossil record
relaxed molecular clocks
diversification
calibration.

Presentation Type: Symposium or Colloquium Presentation
Session: C1
Location: Summit/Boise Centre
Date: Monday, July 28th, 2014
Time: 4:15 PM
Number: C1011
Abstract ID:579
Candidate for Awards:None