Premium
Evolution at the tips: Asclepias phylogenomics and new perspectives on leaf surfaces
Author(s) -
Fishbein Mark,
Straub Shan C. K.,
Boutte Julien,
Hansen Kimberly,
Cronn Richard C.,
Liston Aaron
Publication year - 2018
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/ajb2.1062
Subject(s) - biology , phylogenomics , character evolution , trichome , clade , phylogenetics , phylogenetic tree , evolutionary biology , botany , gene , biochemistry
Premise of the Study Leaf surface traits, such as trichome density and wax production, mediate important ecological processes such as anti‐herbivory defense and water‐use efficiency. We present a phylogenetic analysis of Asclepias plastomes as a framework for analyzing the evolution of trichome density and presence of epicuticular waxes. Methods We produced a maximum‐likelihood phylogeny using plastomes of 103 species of Asclepias . We reconstructed ancestral states and used model comparisons in a likelihood framework to analyze character evolution across Asclepias . Key Results We resolved the backbone of Asclepias , placing the Sonoran Desert clade and Incarnatae clade as successive sisters to the remaining species. We present novel findings about leaf surface evolution of Asclepias —the ancestor is reconstructed as waxless and sparsely hairy, a macroevolutionary optimal trichome density is supported, and the rate of evolution of trichome density has accelerated. Conclusions Increased sampling and selection of best‐fitting models of evolution provide more resolved and robust estimates of phylogeny and character evolution than obtained in previous studies. Evolutionary inferences are more sensitive to character coding than model selection.