Towards a phylogenetic nomenclature ofTracheophyta

Abstract

This is an abbreviated version of a paper that appears in full in the Electronic supplement to Taxon. Phylogenetic definitions are provided for the names of 20 clades of vascular plants (plus 33 others in the electronic supplement). Emphasis has been placed on well‐supported clades that are widely known to non‐specialists and/or have a deep origin within Tracheophyta or Angiospermae. These treatments follow the draft PhyloCode and illustrate the application of phylogenetic nomenclature in a variety of nomenclatural and phylogenetic contexts. Phylogenetic nomenclature promotes precision in distinguishing crown, apomorphy‐based, and total clades, thereby improving communication about character evolution and divergence times. To make these distinctions more transparent without increasing the number of entirely different names that must be learned, the following naming conventions (which have been adopted in the most recent draft of the PhyloCode) are employed here: widely known names are applied to crown clades, and the corresponding total clade (i.e., crown plus stem) is named “Pan‐X”, where “X” is the name of the crown (e.g., Pan‐Spermatophyta for the total clade of plants that share more recent ancestry with extant seed plants than with any other crown clade). If a name “X” that is based etymologically on an apomorphy is applied to the crown, the name “Apo‐X” is applied to the clade for which this trait is synapomorphic (e.g., Apo‐Spermatophyta for the clade originating from the first plant with seeds). Crown clade names can be defined by three kinds of definitions, two of which are used here: standard node‐based and branch‐modified node‐based. The latter is particularly useful when outgroup relationships of a crown clade are better known than basal relationships within the clade. Criteria and approaches used here to choose among competing preexisting names for a clade, to select a definition type, to choose appropriate specifiers, and (in some cases) to restrict the use of a name to certain phylogenetic contexts may be widely applicable when naming other clades. The phylogenetic definitions proposed here should help focus future discussions of the PhyloCode on real definitions rather than simplified hypothetical ones.

Evolution of spur-length diversity in Aquilegia petals is achieved solely through cell-shape anisotropy

“…Thus, minimal elaboration of an existing developmental mechanism can rapidly generate spur-length variation in the genus in concert with a specific ecological pressure, the presence of a pollinator with a dramatically longer tongue. Interestingly, there are taxa within the genera Semiaquilegia and Urophysa, which are very closely related to Aquilegia, that lack elongated spurs but produce small nectary cups or extremely short spurs [6,13,14], similar to very early developmental stages in Aquilegia. This implies that the evolutionary innovation underlying spur formation and the rapid radiation of Aquilegia may have been the mechanism of tuning cell anisotropy, which led to the elaboration of the nectary cup.…”

Angiosperm Phylogeny Based on 18S/26S rDNA Sequence Data: Constructing a Large Data Set Using Next-Generation Sequence Data

“…Amborellaceae and Nymphaeaceae are then followed by Austrobaileyales as subsequent sisters to all other angiosperms (Mesangiospermae sensu Cantino et al 2007). Within the Mesangiospermae, monocots (Monocotyledoneae) are sister to the rest of the angiosperms (magnoliids, Chloranthales, and eudicots).…”

Evolutionary Relationships inEphedra(Gnetales), with Implications for Seed Plant Phylogeny

“…The B/MCMC analysis of the subset including only chloroplast data results in a sister relationship between Gnetales and Cupressophyta sensu Cantino et al (2007; i.e., Cupressaceae, ''Taxodiaceae,'' Cephalotaxaceae, Taxaceae, Sciadopityaceae, Araucariaceae, and Podocarpaceae; 0.98/-). In the MP analysis of chloroplast data, Gnetales are sister to all other seed plants (-/96), and conifers are monophyletic (-/92).…”