Dated phylogeography of western North American subalpine marshmarigolds (Caltha spp., Ranunculaceae): Miocene–Pliocene divergence of hexaploids, multiple origins of allododecaploids during the Pleistocene, and repeated recolonization of Last Glacial Maximum glaciated regions

Abstract

Aim In order to understand how a montane polyploid species complex responded to Cenozoic mountain uplift and climate change, we reconstructed the biogeographic history of the subalpine marshmarigold polyploid complex, including Caltha biflora, Caltha chionophila and Caltha leptosepala. Phylogenies at multiple taxonomic levels were used to estimate the timing of species divergence, allopolyploid formation and migration patterns, and to identify Last Glacial Maximum (LGM) refugia and recolonization routes. Location Western North America. Methods A fossil‐calibrated chronogram was estimated for the eudicot order Ranunculales that was in turn used to set age priors on genus‐level Caltha phylogenies. Nuclear ribosomal and chloroplast DNA sequence data were collected from subalpine marshmarigolds, including 161 specimens from across the geographical range of the complex. The datasets were analysed under a strict or relaxed molecular clock and a structured coalescent model of evolution estimated under a Bayesian framework. Results Hexaploids C. biflora and Caltha chionophila diverged in the Upper Miocene to Lower Pleistocene (chloroplast and nuclear dataset estimates overlapping at the Miocene–Pliocene boundary), and upon secondary contact formed allododecaploid C. leptosepala bidirectionally and at least three times. The hexaploids persisted to the south of LGM icesheets and recolonized LGM glaciated regions in multiple waves, mainly from the C. biflora clade in the Cascades and Coast Ranges. Main conclusions This study of a widespread western North American plant lineage shows a complex response to past geological and climatic changes, with multiple refugia, allopolyploidization events, and migrations during the Pleistocene. Bidirectional allododecaploid formation has resulted in cryptic lineages, some of which (C. leptosepala in the Cascades and Coast Ranges) have been more successful at reclaiming glaciated regions than others (C. leptosepala in the Northern Rockies).

A dated phylogeny of Lardizabalaceae reveals an unusual long‐distance dispersal across the Pacific Ocean and the rapid rise of East Asian subtropical evergreen broadleaved forests in the late Miocene

“…Analysis 2 suggests a crown‐group age of 76.9 Ma (95% HPD: 45.98–109.3; node 1) for the family, which is older than the estimate of Wefferling and Hoot (; 44.88 Ma), but our credibility interval overlapped with the assumptions of Anderson et al () of 66 and 95 Ma inferred by penalized likelihood and nonparametric rate smoothing methods, respectively. Wefferling and Hoot () estimated the split time between Lardizabaleae and Akebieae and the crown age of Akebieae at 18.63 and 7.86 Ma, respectively, which are in agreement with our results: 24.4 Ma (95% HPD: 12.23–41.31; node 2) and 7.49 Ma (95% HPD: 3.76–13.77; node 3). There was no temporal conflict between the South American lineage and the Tertiary wood record from Patagonia (Schönfeld, ), although the exact age of the fossil remains unclear.…”

Re‐delimitation of Tinospora (Menispermaceae): Implications for character evolution and historical biogeography

“…We set a 101 Ma maximum age for the root, which is the estimated crown age of the Chasmantheroideae (Wang & al., 2012), with a normal distribution and a standard deviation of three. A recent study reported a relatively younger age (80.14 Ma) for the crown age of the subfamily (Wefferling & Hoot, 2018). To explore the impact of the root age on the estimates, we also constrained the root to 80.14 Ma and reran the dating analysis using the cpDNA data.…”

Small-scale alpine topography at low latitudes and high altitudes: refuge areas of the genus Chrysanthemum and its allies

“…The evolution of species is driven by the environment. To explore the key issues of evolutionary history, such as the region of origin, divergence time, radiation path, and distribution range, it is necessary to combine fossil 21 , phytogeographical 22 , ecological 23 , 24 , and other evidence to obtain reasonable and accurate results. In these aspects, there is a paucity of research on Chrysanthemum , Ajania , and their allies (but see Li et al 25 ), especially on the phytogeography and ecology within their areas.…”