When tropical and subtropical congeners met: Multiple ancient hybridization events within Eriobotrya in the Yunnan‐Guizhou Plateau, a tropical‐subtropical transition area in China

Abstract

Global climate changes during the Miocene may have created ample opportunities for hybridization between members of tropical and subtropical biomes at the boundary between these zones. Yet, very few studies have explored this possibility. The Yunnan-Guizhou Plateau (YGP) in Southwest China is a biodiversity hotspot for vascular plants, located in a transitional area between the floristic regions of tropical Southeast Asia and subtropical East Asia. The genus Eriobotrya (Rosaceae) comprises both tropical and subtropical taxa, with 12 species recorded in the YGP, making it a suitable basis for testing the hypothesis of between-biome hybridization. Therefore, we surveyed the evolutionary history of Eriobotrya by examining three chloroplast regions and five nuclear genes for 817 individuals (47 populations) of 23 Eriobotrya species (including 19 populations of 12 species in the YGP), plus genome re-sequencing of 33 representative samples. We concluded that: (1) phylogenetic positions for 16 species exhibited strong cytonuclear conflicts, most probably due to ancient hybridization; (2) the YGP is a hotspot for hybridization, with 11 species showing clear evidence of chloroplast capture; and (3) Eriobotrya probably originated in tropical Asia during the Eocene. From the Miocene onwards, the intensification of the Eastern Asia monsoon and global cooling may have shifted the tropical-subtropical boundary and caused secondary contact between species, thus providing ample opportunity

Increasing Taxa Sampling Provides New Insights on the Phylogenetic Relationship Between Eriobotrya and Rhaphiolepis

“…E. deflexa, E. cavaleriei and E. fragrans are located in the Clade 5, likewise significant support in the ITS data ( Kang et al, 2021 ) and the nuclear genes data ( Chen et al, 2021 ) rather than the study of Idrees et al (2020a) ; Idrees et al (2020b) , Chen et al (2020) , and Liu et al (2020) . In clade 6, E. prinoides is closely related to E. elliptica and E. serrata, but the relationship is not supported in the study of Idrees et al (2020a) ; Idrees et al (2020b) ; Kang et al (2021) , and Chen et al (2021) . Three Myanmar Eriobotrya species E. glabrescens , E. platyphylla , and E. sp4 , were located in Clade 7 with six Chinese Eriobotrya species, E. bengalensis , E. bengalensis var .…”

“…E. laoshanica is located in the Clade 4, while E. malipoensis is located in the Clade 3 with E. grandiflora, E. hookeriana, E. japonica, E. petiolate, E. sp2, and E. × daduheensis. E. deflexa, E. cavaleriei and E. fragrans are located in the Clade 5, likewise significant support in the ITS data (Kang et al, 2021) and the nuclear genes data (Chen et al, 2021) rather than the study of Idrees et al (2020a); Idrees et al (2020b), Chen et al (2020), andLiu et al (2020). In clade 6, E. prinoides is closely related to E. elliptica and E. serrata, but the relationship is not supported in the study of Idrees et al (2020a); Idrees et al (2020b); Kang et al (2021), andChen et al (2021).…”

“…It has long been difficult to classify the genera of the Maleae tribe, which may be due to polyploidy events, rapid radiations, frequent hybridizations, and/or ancient diversification among some clades ( Wolfe and Wehr, 1988 ; Robertson et al, 1991 ; Vamosi and Dickinson, 2006 ; Campbell et al, 2007 ; Dickinson et al, 2007 ; Li et al, 2012 ; Lo and Donoghue, 2012 ; Xiang et al, 2016 ; Liu et al, 2019 ). The latest research also shows that multiple ancient hybridization and chloroplast capture events within Eriobotrya in the Yunnan-Guizhou Plateau ( Chen et al, 2021 ). This makes the taxonomic study of Eriobotrya more complicated.…”

Eriobotrya crassifolia (Rosaceae), a new species from Yunnan Province, China

“…However, based on the 197 single copy nuclear genes, the species tree showed that this new species was closely related to E. fragrans and E. deflexa with low support (quartet score, QS = 38; local posterior probabilities, Astral-PP = 0.74) (fig. 5b in Chen et al 2022), while the divergence time estimation indicated that it was sister to the sympatric species of E. laoshanica (fig. 8b in Chen et al 2022), in which this new species was marked with E. sp1.…”

“…5b in Chen et al 2022), while the divergence time estimation indicated that it was sister to the sympatric species of E. laoshanica (fig. 8b in Chen et al 2022), in which this new species was marked with E. sp1. All this molecular evidence identified that E. angustissima was distantly related with the new species although they were similar in morphology.…”