ID: 613 / 71

Category: Symposia

Track: Pending

Proposed Symposium Title: APG V AND THE CHALLENGE OF TRANSLATING PHYLOGENY INTO CLASSIFICATION WHEN GENE TREES CONFLICT

Abstract: The Angiosperm Phylogeny Group classification has provided a stable foundation for plant biology for a quarter century. With contributions from 29 authors, input from many additional members of the systematics community, a clear set of guiding principles, and explicit reliance on molecular-based phylogeny, the APG system has stabilized names, provided a basis for herbarium organization, and offered a framework phylogeny that has been used in studies ranging from molecular evolution to landscape ecology. Moreover, the APG model has been adopted by systematists working across the Tree of Life. The shared use of mostly plastid genes, coupled with transparent translation of clades to recognized taxonomic groups, has enabled continued progress toward placing all angiosperms into a single, well-supported classification. The most recent update, APG V, has clarified additional problematic issues and identified groups that continue to require further study. Most notably, APG V has confronted the challenge of gene tree discordance, including discordance between plastid and nuclear phylogenies and discordance among nuclear gene trees. Although common at shallow evolutionary scales and resulting from reticulation, incomplete lineage sorting, and other processes, such discordance was generally unexpected at deeper phylogenetic levels, particularly those involving clades named as families, orders, and above. Recent nuclear-based phylogenies have, however, revealed evidence of ancient reticulation, raising new challenges for angiosperm classification. In this Symposium, the speakers will review the principles and history of the APG system of classification, provide an overview of APG V, present comparisons of nuclear and plastid phylogenies, and explicitly address the challenges and possible solutions of reticulation and other processes that lead to well-supported phylogenetic discordance. This Symposium will attract those interested in the theory and practice of classification, reticulation and its impacts, and plant evolution, and all users of scientific names.

Speaker 1: Mark W. Chase Royal Botanic Gardens, Kew m.chase@kew.org Whence APG and what the future might hold

Speaker 2: Alexandre Zuntini Royal Botanic Gardens, Kew (currently a fellow from Brazil) a.zuntini@kew.org The impact of nuclear data on APG V

Speaker 3: Douglas E. Soltis and Pamela S. Soltis (split talk) University of Florida dsoltis@ufl.edu; psoltis@flmnh.ufl.edu Reconciling gene-tree discordance in classification

Topics (Up to three): Hybrids and Hybridization

Topic 2: Phylogenetics and Phylogenomics

Topic 3: Systematics

Justification: The proposed Symposium should be of broad interest, intersecting at least four of the IBC focal topics: Botanical History, Hybrids and Hybridization, Phylogenetics and Phylogenomics, and Systematics and Taxonomy. The organizers and proposed speakers come from three continents and represent multiple axes of diversity – career stage, gender, geography – and we anticipate that the Symposium will attract diverse contributed presentations from diverse authors on topics from reticulation to resolution of difficult regions of angiosperm phylogeny to new perspectives on classification. We also request the option of two back-to-back Symposia, should the number and quality of submitted abstracts be high.