Since Charles Darwin termed it his "abominable mystery", rapid speciation in angiosperms has eluded simple explanation. Climate has been implicated as a major catalyst of diversification, but its effects are thought to be inconsistent over time, between clades and across regions of the globe. Here we test the influence of climate change and geography-related climate factors on the diversification of the orchidoid orchids, a diverse subfamily of enduring fascination since Darwin's time. We show that global cooling spurred speciation in assemblages of orchidoids throughout the earth. Employing a phylogenetic framework, we demonstrate that speciation rate is correlated with historic changes in global temperature, but not atmospheric CO2 or sea-level. Cooling-driven diversification is consistent in all tribes, and in Disa, a large genus with well-supported signatures of adaptive evolution. We find no evidence for influences of geography-related climate factors, such as latitudinal and elevation gradients, or for cradles of diversity, in analyses of tip rates in the context of 1.5 million georeferenced records. Rather than being an abominable mystery, our results support a simple hypothesis that climate change can rapidly accelerate adaptive radiation in assemblages throughout the globe. Our findings raise the possibility that there are undiagnosed roles for climate change in other major radiations and indicate how contemporary climate change will influence long-term evolutionary processes.

The Cretaceous-Paleogene mass extinction event (K–Pg) witnessed up to 75% of animal species going extinct, most notably among these are the non-avian dinosaurs. A major question in macroevolution is whether this extinction event influenced the rise of flowering plants (angiosperms). The fossil record suggests that the K–Pg event had a minor impact on the extinction rates of angiosperm lineages, yet the diversification of extant angiosperms was delayed and started after the K–Pg boundary. However, phylogenetic evidence for angiosperm extinction dynamics remains unexplored. Through the analyses of two angiosperm mega-phylogenies containing ~32,000–74,000 extant species, here we show relatively constant extinction rates throughout geological time and no evidence for a mass extinction at the K–Pg boundary. Despite uncertainty of earliest angiosperm branching times, their staggering diversity, and complex evolutionary dynamics, our preliminary analyses provide congruent results with the fossil record and support the macroevolutionary resilience of angiosperms to the K–Pg mass extinction.

Cancer is a highly-diverse disease and as the second-leading cause of death worldwide is a focus of drug discovery research. Natural products have been shown to be a useful source of novel molecules for the treatment of cancer. It is likely there are many plants with undiscovered molecules of therapeutic value, however identifying new leads from among the vast diversity of plants is very challenging. Traditional knowledge might inform bioprospecting by predicting lineages of plants rich in therapeutically useful molecules. Here, we characterise the phylogenetic diversity of plants used traditionally to manage cancer. We demonstrate the independent and repeated targeting of specific lineages of plants by different peoples in different parts of the world. That the same lineages are used to treat different cancers is suggestive of independent discovery of therapeutic value. However, the lineages we report here as rich in plants used traditionally to treat cancer coincide with those for other ethnobotanical applications, and contain few plants with proven anti-cancer activity. It is likely that the traditional knowledge recorded and explored here is shaped by selection of plants conferring milder effects for treating wider symptoms, such as tiredness or nausea, rather than for halting tumour growth. Accurate prediction of useful plant lineages for cancer management requires more nuanced information than is commonly provided in ethnobotanical records.

Many drivers of diversification have been identified across the angiosperm Tree of Life, ranging from abiotic factors, such as climate change, to biotic factors such as key adaptations. While this provides invaluable evolutionary insight into the rise of major angiosperm lineages, our understanding of the complexity underlying this remains incomplete. In species-rich families such as Cactaceae, simple explanations of triggers of diversification are insufficient. Their sheer morphological and ecological diversity, and wide distribution across heterogeneous environments, render the identification of key forces difficult. Cactus diversification is likely shaped by multiple drivers, which themselves interact in complex ways. This complexity is extremely difficult to disentangle, but applying modern analytical methods to extensive datasets offers a solution. Here, we investigate the heterogeneous diversification of the iconic Cactus family. We reconstruct a comprehensive phylogeny, build a dataset of 39 abiotic and biotic variables, and predict the variables of central importance to tip-speciation rate variation using Machine Learning. State-dependent diversification models confirm that a rich range of eleven abiotic and biotic variables filtered as important by Machine Learning shape Cactus diversification. Of highest importance is an atypical latitudinal gradient in speciation rates, which is spatially decoupled from richness hotspots. Of medium importance is plant size, shaped by growth form. Of lesser, but significant, importance is soil composition, bioclimate, topography, geographic range size, and chromosome count. However, it is unlikely that any one of these eleven variables is of primary importance without the complex interactions formed with others. Our results contribute to our understanding of one of the most iconic angiosperm families, while revealing the need to account for the complexity underlying macroevolution.

The succulent syndrome is one of the most iconic life strategies in angiosperms, maximising water storage through a suite of adaptations to water-scarcity. Though succulence is considered a classic case of convergent evolution driven by shared environmental drivers, we lack a full understanding of whether the timing and drivers of the diversification of succulent lineages are, in fact, concordant. Here we analyse time-calibrated phylogenetic reconstructions of the seven richest lineages of succulents, and study diversification dynamics in relation to abiotic variables. Our analyses reveal different levels of synchronicity and relation with aridity. The impact of atmospheric CO2 on succulent macroevolution is varied. While transitions and radiations are especially concentrated in recent time, following a collapse of atmospheric CO2 ~15 million years ago, CO2-dependent diversification is not supported in most lineages. With the exception of Euphorbia, we find that succulence elevates net diversification, though the effects on underlying speciation and extinction disagree. The phylogenetic distribution of transitions to succulence and rate shift increases suggest these phenomena are decoupled, indicating that succulence might not adhere to a classic key innovation model. We discuss that these evolutionary patterns reveal the ecological complexity of the succulent strategy, beyond simplistic interpretations as adaptations towards aridity.