Phylogeography of the endangered orchids Cypripedium japonicum and Cypripedium formosanum in East Asia: Deep divergence at infra‐ and interspecific levels

Abstract

To date, little is known about the past evolutionary trajectories of rare and endangered orchids native to mainland China, Japan, and Korea (the CJK region). In this study, we focus on two endangered orchids, Cypripedium japonicum (present in the three countries) and C. formosanum (endemic to Taiwan), to understand the divergence/speciation models that would have been operating in this group, including genetic diversity, geographic structure, and colonization pathways across the region. Using a combination of five cpDNA regions, we reconstructed phylogenetic trees and investigated the genetic diversity/structure of 20 populations. Ecological niche modeling was used to gain insight into the paleodistribution and dispersal corridors at the Last Glacial Maximum and to survey climatic niche differences. Populations from mainland China + Korea, Japan, and Taiwan formed three distinct monophyletic lineages and were placed into separate genetic clusters, agreeing with geographic barriers and species boundaries. Populations of C. japonicum in mainland China harbored the highest diversity, suggesting the presence of multiple glacial refugia. The Korean populations would have originated from either western/central or eastern China, probably using a dispersal corridor across the East China Sea shelf. The divergence of C. formosanum is proposed under an allopatric speciation model, also highly influenced by a climate niche shift. In the context of previous studies, a deep divergence in cpDNA sequences between Chinese + Korean and Japanese populations of C. japonicum may be taken as an example of the speciation events of the CJK flora since the late Neogene that have led to its current species richness.

Transcriptome data reveals the conservation genetics of Cypripedium forrestii, a plant species with extremely small populations endemic to Yunnan, China

“…Previous genetic studies of other orchid species data are based on chloroplast DNA fragments, and yielded much higher nucleotide diversity. For example, the nucleotide diversity of C. japonicum is 0.88e -3 ( Han et al., 2022 ); C. tibeticum has a much higher nucleotide diversity of 1.52e -3 ( Guo et al., 2019 ). However, nucleotide diversity estimated using transcriptome or genome data should be more accurate, as it was computed based on a much higher number of loci.…”

Genome‐wide RAD sequencing data suggest predominant role of vicariance in Sino‐Japanese disjunction of the monotypic genus Conandron (Gesneriaceae)

“…Similarly, an ecological niche divergence scenario was found between Cypripedium formosanum Hayata (endemic to Taiwan Island) and its relative C. japonicum Thunb. (widespread in mainland China, Korea, and Japan) (Han et al, 2022). In contrast, the strong genetic differentiation between mainland Chinese and Japanese populations cannot be translated to the climatic niche, probably because they share the same climatic background (Fig.…”

Vanilla pompona Schiede (Vanilloideae-Orchidaceae): Morphological Variation of the Labellum in the Mexican Localities of Veracruz, Puebla, Jalisco and Oaxaca

“…Morphotype VI is found on the Pacific coast and is in the Sierra Madre del Sur [54], while morphotype II is found on the Gulf of Mexico slope and belongs to the Sierra Madre Oriental [56]. These mountain chains function as geographic barriers and could partly explain the genetic diversity and speciation in orchids [57]. Moreover, it has been documented that the Gulf of Mexico has greater influence in the warm subhumid climate [55] where morphotype II is found, while morphotype VI is found in a warm humid climate (Table 2).…”