Abstract Detail

A synthesis of new paleontological and phylogenomic perspectives on gymnosperm evolution

Leslie, Andrew [1].

Using conifers to explore the challenges of integrating molecular and morphological data in reconstructing gymnosperm phylogeny.

Molecular data has greatly improved our understanding of relationships within major seed plant clades, but can only provide a limited understanding of the phylogeny and patterns of character evolution among higher-level groups because so many are extinct. The fossil record is therefore essential to reconstruct seed plant evolution generally, and gymnosperm evolution specifically, but integrating morphological and molecular approaches remains difficult. Conifers, which have both high extant diversity and an extensive fossil record, are a good group in which to explore some of the challenges in integrating these two types of data. Here I use an updated time-calibrated conifer phylogeny that samples around 90% of all species, and focus on the evolution of conifer reproductive characters, which form the bulk of the characters used in previous morphological conifer phylogenies. Backbone relationships among clades, as revealed by molecular data, can help clarify some long-standing questions in reproductive evolution; for example, they suggest that the highly modified “berry” of Taxaceae must be derived from a more typical ancestral cone. On the other hand, the pervasive “stemminess” of extant conifer phylogeny makes it difficult to infer specific ancestral seed cone states for many major clades and thus to identify potentially useful synapomorphies for placing fossil taxa. In general, fossil seed cones also become increasingly difficult to assign to modern groups before the Jurassic, because characters that are variable in early conifers are often either not present or are not variable in living clades; such non-overlapping variation makes it difficult to build well-resolved and well-supported morphological phylogenies. Detailed analyses of individual characters, combining insights from molecular topologies, functional studies, and the fossil record, may represent a way forward by allowing a greater understanding of the specific morphological characters that must ultimately be used to integrate fossil and molecular data sets.

1 - Brown University, Ecology And Evolutionary Biology, Box G-W, 80 Waterman Street, Providence, RI, 02912, United States

Keywords:
gymnosperm
conifer
divergence time
seed cone.

Presentation Type: Colloquium Presentations
Session: C04, A synthesis of new paleontological and phylogenomic perspectives on gymnosperm evolution
Location: 102/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 2:45 PM
Number: C04006
Abstract ID:550
Candidate for Awards:None