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Aim Less than 6% of the worlds described plant species have been assessed on the IUCN Red List, leaving many species invisible to conservation prioritization. Large-scale Red List assessment of plant species is a challenge, as most species' ranges have only been resolved to a coarse scale. As geographic distribution is a key assessment criterion on the IUCN Red List, we evaluate the use of coarse-scale distribution data in predictive models to assess the global scale and drivers of extinction risk in an economically important plant group, the bulbous monocotyledons.Location Global.Methods Using coarse-scale species distribution data, we train a machine learning model on biological and environmental variables for 148 species assessed on the IUCN Red List in order to identify correlates of extinction risk. We predict the extinction risk of 6439 'bulbous monocot' species with the best of 13 models and map our predictions to identify potential hotspots of threat.Results Our model achieved 91% classification accuracy, with 88% of threatened species and 93% of non-threatened species accurately predicted. The model predicted 35% of bulbous monocots presently 'Not Evaluated' under IUCN criteria to be threatened and human impacts were a key correlate of threat. Spatial analysis identified some hotspots of threat where no bulbous monocots are yet on the IUCN Red List, for example central Chile.Main conclusions This is the first time a machine learning model has been used to determine extinction risk at a global scale in a species-rich plant group. As coarse-scale distribution data exist for many plant groups, our methods can be replicated to provide extinction risk predictions across the plant kingdom. Our approach can be used as a low-cost prioritization tool for targeting fieldbased assessments.

Species radiations, despite immense phenotypic variation, can be difficult to resolve phylogenetically when genetic change poorly matches the rapidity of diversification. Genomic potential furnished by palaeopolyploidy, and relative roles for adaptation, random drift and hybridisation in the apportionment of genetic variation, remain poorly understood factors. Here, we study these aspects in a model radiation, Syzygium, the most species-rich tree genus worldwide. Genomes of 182 distinct species and 58 unidentified taxa are compared against a chromosome-level reference genome of the sea apple, Syzygium grande. We show that while Syzygium shares an ancient genome doubling event with other Myrtales, little evidence exists for recent polyploidy events. Phylogenomics confirms that Syzygium originated in Australia-New Guinea and diversified in multiple migrations, eastward to the Pacific and westward to India and Africa, in bursts of speciation visible as poorly resolved branches on phylogenies. Furthermore, some sublineages demonstrate genomic clines that recapitulate cladogenetic events, suggesting that stepwise geographic speciation, a neutral process, has been important in Syzygium diversification.

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Causonis (Vitaceae) is widely distributed in the tropical, sub-tropical and temperate regions from Asia to Australia. The genus was established by Rafinesque in 1830 but included under Cayratia by Gagnepain in 1911. Generic status of Causonis was restored in 2013, but circumscription of the genus and its species remained poorly understood. Here, we sample 92 accessions of Causonis to reconstruct the phylogenetic relationships within the genus using four chloroplast loci (atpB-rbcL, trnC-petN, trnH-psbA, trnL-F) and three nuclear loci (AS1, At103, ITS). Both the chloroplast and nuclear data support the monophyly of Causonis, and relationships among major clades of the genus are well-supported based on the chloroplast data. The first diverged clade consists of two species both endemic to Australasia. Evolutionary trends of eight morphological characters are tested through ancestral character state reconstruction using the chloroplast dataset. We recognize 16 species and 4 varieties in Causonis, including two new species: C. australasica sp. nov. and C. glauca sp. nov. We herein make 10 new combinations for eight species and two varieties. The widespread Causonis japonica is also redefined based on morphological and molecular evidence.