Thirty clues to the exceptional diversification of flowering plants

Abstract

15• The identified deep time diversification shifts are clues to identify ultimate drivers of angiosperm megadiversity, which probably involve multivariate interactions among intrinsic traits and extrinsic forces. An enhanced understanding of angiosperm diversification will involve a more precise phylogenetic location of diversification shifts, and integration of fossil information. 35

Monocot plastid phylogenomics, timeline, net rates of species diversification, the power of multi‐gene analyses, and a functional model for the origin of monocots

“…Three of the four broad accelerations of diversification we detected in monocots accord with one or more previous studies (Givnish et al, 2015;Spriggs et al, 2015;Magallón et al, 2018). In general, however, there is scale dependence in the resolution of such accelerations.…”

“…The general decline in numbers of diversification accelerations with the taxonomic breadth of studies may reflect a lower intensity of taxon sampling or fossil calibrations, or greater background-foreground contrasts in broader studies that impair ability to detect some accelerations. The accelerations identified by Magallón et al (2018) but not by us may reflect their inability to obtain correct tree resolution with far more limited sequence data (three plastid genes, 18S, 26S nrDNA): Arecales are not sister to Commelinales-Zingiberales, and Tecophilaeaceae are not part of the Asparagales clade sister to Doryanthaceae (Fig. 1).…”

“…Givnish et al (2011) found two accelerations within Bromeliaceae not detected in the present study. In an across-angiosperms analysis, Magallón et al (2018) detected five significant accelerations of diversification in monocots, corresponding to all Poaceae, all Orchidaceae, Cyperaceae and allies, Arecales + Commelinales + Zingiberales, and Asparagales sister to Doryanthaceae but including Tecophilaeaceae. That is, broader analyses-in this case and the others mentioned-often failed to detect important accelerations of net diversification at finer phylogenetic scales.…”

Key questions and challenges in angiosperm macroevolution

“…It has become increasingly clear that high diversification rates leading to extant angiosperm species diversity do not characterize angiosperms as a whole (Sanderson & Donoghue, ). Several angiosperm‐wide studies have relied on the increasingly well‐understood molecular phylogeny to detect exceedingly species‐rich clades (Magallón & Sanderson, ; Magallón & Castillo, ) or to investigate the placement and timing of diversification shifts, either by analyzing the distribution of species richness among terminals (Davies et al ., ; Smith et al ., ) or by using explicit birth–death models (Tank et al ., ; Magallón et al ., ). These studies have identified a partially overlapping set of diversification increases, scattered across the phylogeny.…”

“…Available information on phylogenetic relationships, time of origin and distribution of species richness among angiosperm clades indicates that, as in many other biological groups, among‐lineage distribution of diversity is highly heterogeneous. In many cases, a single or a few species‐poor branches form consecutive sister lineages to a megadiverse clade (‘depauperons’ sensu Donoghue & Sanderson, ), but other species‐poor lineages are immersed within a clade that is highly diverse (Magallón et al ., ). Depauperons are explained as lineages that diverged before or along the assembly of complex innovations in particular ecological and physical settings (‘synnovation’; Donoghue & Sanderson, ).…”