Stratigraphic adjustment for alternative seed plant evolution scenarios: an approach based on morphological characters.

ESCAPA, IGNACIO; NIXON, KEVIN; GANDOLFO, MARIA A.

Boise

Congreso; BOTANY 2014; 2014

A phylogenetic tree implies a temporal order of successive branching events, while the phylogenetic position of terminal fossil taxa also specifies temporal information in the context of the stratigraphic record. If these two sources of temporal information are known independently, they can be compared in order to measure their congruence. Several techniques (e.g., MSM*, GER) have been developed to describe the relative agreement between phylogenetic trees and the chronostratigraphic data associated with fossil taxa. On the other hand, phylogenetic trees also can estimate the order of appearance of morphological character states. Following the same reasoning, the temporal information contained in phylogenetic trees can be compared with the order of appearance of character states in the fossil record. In this presentation we use a new protocol developed to evaluate congruence between fossil record and alternative hypotheses about the evolution of the major extant and extinct seed plant groups. The new method requires well-supported, dense phylogenies (typically based on molecular data), universally coded morphological features for extant taxa, carefully identified and characterized fossils, and placement of the fossils on the tree based on morphology. Our initial analysis includes a discussion of alternative positions for Gnetales and different scenarios proposed for the origin of flowering plants. The use of this newly implemented method will allow a more precise comparison among alternative evolutionary theories and the fossil record, enhancing the crucial role of fossil taxa in order to deeply understand the origin, diversification, extinction and relationships of major seed plant groups.