Phylogeny, origin, and biogeographic history of Aesculus L. (Sapindales) – an update from combined analysis of DNA sequences, morphology, and fossils

Abstract

Conflicting phylogenies and biogeographic hypotheses for Aesculus L. were reevaluated using data integrating morphology, fossils, and DNA sequences. A more robust phylogeny of Aesculus was constructed by increasing taxon and character sampling to include 42 morphological characters and five DNA regions including rps16, trnHK, matK, ITS, and part of the LEAFY gene. Our analyses revealed three well‐supported major lineages in Aesculus. These are sect. Calothyrsus excluding A. californica, sect. Macrothyrsus + A. californica, and sect. Aesculus + sect. Pavia + sect. Parryana. The relationship of sect. Aesculus to sect. Parryana + sect. Pavia is strongly supported and previously unreported. Relationships among the three major clades remained incompletely resolved. Biogeographic and divergence time analyses using DIVA and Multidivtime support a Paleocene origin of Aesculus in eastern Asia and western North America, and showed that the genus subsequently dispersed into eastern North America, Central America, and Europe. Our results support that Aesculus originated as an element of the Paleogene mesophilic flora in the Beringian region with multiple eastward migrations characterizing the early spatial history of this genus. This biogeographic history supports Trans‐Beringian migration of plants in the very early Paleogene.

Intercontinental disjunctions between eastern Asia and western North America in vascular plants highlight the biogeographic importance of the Bering land bridge from late Cretaceous to Neogene

“…Persoon (4 species), an Asian clade (3–10 species), and the species Aesculus californica Nutt. (Xiang et al, ; Forest et al, ; Harris & Xiang, ; Harris et al, , ). Extant Aesculus species are distributed across the Northern Hemisphere and each major lineage is restricted to one of the following areas: eastern Asia, western North America, eastern North America, and Europe, except sect.…”

“…Aesculus , which is disjunct in eastern Asia and Europe. However, molecular phylogenetic studies of Aesculus using several DNA regions (Xiang et al, ; Harris et al, , ) have resulted in poorly supported or unresolved relationships among the six major lineages despite strong support for the polytypic lineages (i.e., crown groups). Biogeographic and divergence time analyses support a Paleocene origin of Aesculus in eastern Asia and western North America, and showed that the genus subsequently dispersed into eastern North America, Central America, and Europe (Harris et al, 2009).…”

“…Biogeographic and divergence time analyses support a Paleocene origin of Aesculus in eastern Asia and western North America, and showed that the genus subsequently dispersed into eastern North America, Central America, and Europe (Harris et al, 2009). The genus originated as an element of the Paleogene mesophilic flora in the Beringian region with multiple eastward migrations characterizing the early spatial history of this genus (Harris et al, ). This biogeographic history supports trans‐Beringian migration of plants in the very early Paleogene.…”

Estimating paleoenvironments using ecological niche models of nearest living relatives: A case study of Eocene Aesculus L.

“…Calothyrsus and show that it is more closely related to sect. Macrothyrsus (Xiang et al, ; Harris et al, ). Following the World Wildlife Fund ecoregion classification (Fig.…”

Himalayan Origin and Evolution of Myricaria (Tamaricaeae) in the Neogene

“…50 Ma, the altitude and range of the QTP near the Oligocene-Miocene boundary became sufficient to trigger a reorganization of the Asian climate, as evidenced by the beginning of loess deposition in the Chinese Loess Plateau and the Junggar Basin [18]–[20]. Some evidence confirms that the central areas of the QTP were raised to present altitudes by that time [16], [21]–[22] and uplift of the Himalayas may have also begun at that time [22]–[23]. Uplift of peripheral portions of the plateau has continued at various intervals [24]–[28].…”