Abstract Detail

PhyloCode 2020: Naming the Tree of Life

Soltis, Pamela [1], Soltis, Douglas [2].

Deep Reticulate Evolution and Phylogenetic Nomenclature.

Reticulate evolution poses challenges for any nomenclatural system, the PhyloCode included, because the products of reticulation strictly belong to neither, or both, of their parental clades, and the alternative placements of a reticulate derivative disrupt the reciprocal monophyly of the parental clades. Although this issue is generally considered at shallow phylogenetic levels, such as homoploid hybrid species or allopolyploids that arise from hybridization between recently diverged species, it is increasingly recognized as a potential challenge at deeper phylogenetic levels as well. Examples of ancient polyploidization inferred from genomic and/or transcriptomic data imply ancient reticulation events, even when phylogenies from multiple gene trees are concordant, consistent with hypotheses of hybridization between close relatives. But what if the reticulation involved more distant relatives, such that the parental lineages are today distinct? Rapidly growing examples of discordance among nuclear gene trees and between plastid and nuclear phylogenies deep in angiosperm evolution increasingly point to frequent episodes of ancient reticulation. A key example involves the ‘COM clade’ (Celastrales-Oxalidales-Malpighiales) in Rosidae. Fabidae, one of two major clades of Rosidae, comprises over 51,000 species and has been strongly supported in several phylogenetic analyses. All plastid-based trees support the inclusion of the COM clade within Fabidae, whereas trees reconstructed from nuclear and mitochondrial genes place the COM clade in Malvidae, the second major clade of Rosidae, and morphological evidence also supports this latter placement. Rather than uncertainty, these alternative placements of the COM clade reflect its two parental lineages and illustrate that the COM clade is actually part of both Rosidae and Malvidae. To accommodate this dual placement, we use a maximum-crown-clade definition of Fabidae and a reciprocal definition of Malvidae. This approach ensures that both Fabidae and Malvidae are always sisters, regardless of their exact composition in any given phylogeny. This general approach may be useful in other cases of deep reticulation, such as the possible event(s) that occurred among Cornales, Ericales, and Gentianidae.

1 - University Of Florida, Florida Museum Of Natural History, PO Box 117800, Gainesville, FL, 32611, United States
2 - University of Florida, Florida Museum of Natural History, PO Box 117800, Gainesville, FL, 32611, United States

Keywords:
reticulation
phylogeny
PhyloCode
phylogenetic nomenclature.

Presentation Type: Colloquium Presentations
Session: C08, PhyloCode 2020: Naming the Tree of Life II
Location: /
Date: Thursday, July 22nd, 2021
Time: 12:30 PM(EDT)
Number: C08001
Abstract ID:1028
Candidate for Awards:None