Macroevolutionary dynamics in the early diversification of Asteraceae

Abstract

Spatial and temporal differences in ecological opportunity can result in disparity of net species diversification rates and consequently uneven distribution of taxon richness across the tree of life. The largest eudicotyledonous plant family Asteraceae has a global distribution and at least 460 times more species than its South American endemic sister family Calyceraceae. In this study, diversification rate dynamics across Asteraceae are examined in light of the several hypothesized causes for the family's evolutionary success that could be responsible for rate change. The innovations of racemose capitulum and pappus, and a whole genome duplication event occurred near the origin of the family, yet we found the basal lineages of Asteraceae that evolved in South America share background diversification rates with Calyceraceae and their Australasian sister Goodeniaceae. Instead we found diversification rates increased gradually from the origin of Asteraceae approximately 69.5Ma in the late Cretaceous through the Early Eocene Climatic Optimum at least. In contrast to earlier studies, significant rate shifts were not strongly correlated with intercontinental dispersals or polyploidization. The difference is due primarily to sampling more backbone nodes, as well as calibrations placed internally in Asteraceae that resulted in earlier divergence times than those found in most previous relaxed clock studies. Two clades identified as having transformed rate processes are the Vernonioid Clade and a clade within the Heliantheae alliance characterized by phytomelanic fruit (PF Clade) that represents an American radiation. In Africa, subfamilies Carduoideae, Pertyoideae, Gymnarrhenoideae, Cichorioideae, Corymbioideae, and Asteroideae diverged in a relatively short span of only 6.5millionyears during the Middle Eocene.

The Compositae Tree of Life in the age of phylogenomics

“…Figure displays a tree with the same taxa but generated using a coalescent‐based method (ASTRAL‐II v4.10.2: gene trees with RAxML v8 [Stamatakis, ], GTR+GAMMA, 1000 bootstrap replicates each and then input into ASTRAL‐II using default parameters, Mirarab & Warnow, ). The overall topology of the tree is similar to previous work (Funk et al, ; Huang et al, ; Panero & Crozier, ) with some differences. One area of the tree that varies from previous studies is the finding of a Carduoideae subfamily that is not supported by the data as monophyletic in the Bayesian analysis but monophyly is supported in the ASTRAL tree.…”

“…Two recent phylogenetic studies of the family employed 12 plastid markers for 85 species (Panero & Crozier, ) and 175 markers selected using an orthology detection workflow from transcriptome data for 73 species (see Huang et al, for details). These are the first studies to more fully reconstruct phylogenies at the family‐wide level.…”

Origin of the Rapa endemic genus Apostates: Revisiting major disjunctions and evolutionary conservatism in the Bahia alliance (Compositae: Bahieae)

“…From that perspective, Apostates appears to be a paleoendemic in the Rapa flora, although not as ancient as was considered by Lander (1989). [Note: Younger divergence times for Apostates and other members of the Bahia alliance cannot be ruled out based on results (published too recently for full consideration here) of Panero & Crozier (2016), who excluded Tubulifloridites lilliei type A pollen fossils used by Barreda & al. (2015) from analyses of divergence times in Asterales based on concerns about phylogenetic placement of those fossils (see Panero, 2016;Barreda & al., 2016)].…”

Can climate and soil conditions change the morpho-anatomy among individuals from different localities? A case study in Aldama grandiflora (Asteraceae)

“…The family Asteraceae accounts for approximately 10% of the world's flora (Panero and Crozier, 2012) and is one of the most important among angiosperms, comprising around 1620 genera and 23600 species (Stevens, 2001). Being a large family, the niches occupied by its species vary substantially and a considerable number of anatomical differences can be explained by phenotypic plasticity (Metcalfe and Chalk, 1983), which allow adaptation to different environmental conditions (Dickison, 2000).…”