The Origin And Speciation Of Orchids

Abstract

Summary⍰ Orchids constitute one of the most spectacular radiations of flowering plants. However, their geographical origin, historical spread across the globe, and hotspots of speciation remain uncertain due to the lack of a broad phylogenomic framework.⍰ We present a new Orchidaceae phylogeny based on high-throughput and Sanger sequencing datasets, covering all five subfamilies, 17/22 tribes, 40/49 subtribes, 285/736 genera, and ∼7% (1,921) of the currently 29,524 accepted species. We then use it to infer geographic range evolution, diversity, and speciation patterns by adding curated geographical distribution data through the World Checklist of Vascular Plants.⍰ Orchid’s most recent common ancestor is traced back to the Late Cretaceous in Laurasia. The modern Southeast Asian range of subfamily Apostasioideae is interpreted as relictual, matching the history of numerous clades that went extinct at higher latitudes following the global climate cooled during the Oligocene. Despite their ancient origins, modern orchid species’ diversity mainly originated over the last 5 Ma, with the fastest speciation rates found in south-eastern Central America.⍰ Our results substantially alter our understanding of the geographic origin of orchids, previously proposed as Australian, and further pinpoint the role of Central American as a region of recent and explosive speciation.

Plastid phylogenomics reveals evolutionary relationships in the mycoheterotrophic orchid genusDipodiumand provides insights into plastid gene degeneration

“…This phylogenomic study based on 68 plastid loci provided strong support for the monophyly of Dipodium and its phylogenetic placement as an early diverging lineage within tribe Cymbidieae. Previous phylogenetic studies included only one or two species of Dipodium which precluded assessment of the monophyly of the genus (Pridgeon et al, 2009: Chase et al, 2015; Górniak et al (2010); Batista et al (2014); Freudenstein and Chase (2015); Kim et al, 2020; Serna-Sánchez et al, 2021; McLay et al, 2023; Pérez-Escobar et al, 2023). Our study resolved Dipodium as the diverging early within Cymbidieae after subtribe Cymbidiinae with strong support and thus confirmed previous molecular phylogenetic studies in support of recognition of Dipodium at subtribal level as Dipodiinae (Li et al, 2016; Serna-Sánchez et al, 2021; Kim et al, 2020; Pérez-Escobar et al, 2023).…”

“…For this study, we sampled all known Australian species of section Dipodium and one representative of section Leopardanthus ( Table 1 ). Based on previous molecular systematic studies (Serna-Sánchez et al, 2021; Pérez-Escobar et al 2023; Zhang et al 2023), an extended outgroup from closely related orchid genera within subtribe Eulophiinae ( Eulophia R.Br., Geodorum Andrews) and subtribe Cymbidiinae ( Cymbidium Sw., Acriopsis Reinw. ex.…”

Plastid genome evolution in leafless members of the orchid subfamily Orchidoideae, with a focus onDegranvillea dermaptera

“…taxon sampling but not character sampling), revealing that Degranvillea occupies a position as sister of a species-rich clade of predominantly Central and South American genera (e.g. Aulosepalum, Dichromanthus, Deiregyne, Erystyles, Funkiella, Hapalorchis, Mesadenus, Schiedeella ), in addition to Spiranthes , which has diversified into North America, Eurasia, and Australia (Dueck et al, 2014; Givnish et al, 2015; Serna-Sanchez et al, 2021; Perez-Escobar et al, 2023). Salazar et al (2018) also included matching taxon sampling for the plastid matK and trnL-F regions, but both of these regions have been lost in Degranvillea , thus limiting our analysis to a single locus in ITS.…”

Genome-Wide Identification, Expression, and Molecular Characterization of the CONSTANS-like Gene Family in Seven Orchid Species

“…Here, we identified seven COL genes and investigated their properties, such as chromosome location, gene organization, cis-acting elements, protein-protein interactions (PPIs), and gene expression pattern. In addition, we were surprised to find that the CsiCOL genes in C. sinense may be related to the development of the gynostemium, which is one of the typical characteristics of orchids that distinguishes them from other plants [38]. First, the overexpression of CsiCOL05 and CsiCOL09 in C. sinense protoplasts confirms the regulation of the flowering time and flower development genes.…”