Phylogeny and divergence time estimation of the genus Didymodon (Pottiaceae) based on nuclear and chloroplast markers

Abstract

Didymodon Hedw., with approximately 140 species in the family Pottiaceae, is distributed nearly throughout the world, with the greatest diversity and important ecological functions in drought lands and alpine ecosystems. Several studies involving morphology, molecular systematics, and macro‐systematic analysis have addressed the infrageneric classification of Didymodon, but controversy over the position of the infrageneric and species classification remains due to its high degree of morphological variation in micro‐habitats and strong sensitivity to climate change at regional and global scale. To date, only a few phylogenetic studies have been conducted with an incomplete number of Didymodon species; further, there is no study published regarding the divergence time of Didymodon. Consequently, we conducted a comprehensive phylogenetic analysis of Didymodon species, sampling a total of 107 species, based on one nuclear (ITS) and five chloroplast DNA. Moreover, divergence time analysis was conducted to infer the age of origin and divergence of Didymodon species. Our results presented the largest scale phylogenetic relationship of Didymodon to date and resolved the phylogenetic status of some controversial taxa and the new species. The divergence time estimation showed that Didymodon species originated around the early Cretaceous, and the diversification was concentrated in the Cretaceous and Eocene. Paleoclimate and environmental change have a direct impact on the origin and divergence of Didymodon species by shaping their morphology, resource availability and ecological niche. Our study will help understand species origin and speciation of Didymodon as well as reflecting species adaptability and experience to historical events.

Didymodon manhanensis (Pottiaceae, Bryophyta), a new species from Inner Mongolia steppe, China and its phylogenetic position, based on molecular data

“…is heterogeneous and could be profitably split. In our phylogenetic analyses, this genus is polyphyletic and its species can be classified within several well-supported monophyletic clades, which correspond to other phylogenetic studies of the genus ( Feng et al 2022 ; Jiménez et al 2022 ; Zhang et al in press ). Our results reveal a close relationship between D. manhanensis and two recently-described species in China: D. daqingii and D. obtusus .…”

“…We employed one nuclear (ITS) and two chloroplast markers ( rps 4 and trn M- trn V), which had been used successfully in previous phylogenetic studies in Didymodon s. lat. and enabled the re-use of earlier results and easier interpretation of new data ( Werner et al 2004 , 2005 , 2009 ; Kučera and Ignatov 2015 ; Kučera et al 2018 ; Ronikier et al 2018 ; Jiménez et al 2022 ; Zhang et al in press ). Phylogenetic trees are created and shown separately.…”

“…The taxonomy of genus Didymodon is complicated, involving the differentiation from related genera, such as Barbula Hedw. and the circumscriptions of its infrageneric sections ( Zander 1993 ; Zander 2007 ; Zhang et al in press ). A recent important event associated with Didymodon s. lat.…”

“…and Vinealobryum R.H. Zander, based on macro-evolutionary analysis and the dissilient genus concept applied ( Zander 2013 ; Zander 2019 ). Although initially this revolutionary concept was considered unnecessary or unsupported ( Blockeel and Kučera 2019 ), it has later been supported by molecular phylogenetic data, but with some alterations ( Jiménez et al 2022 ; Zhang et al in press ) and has gained acceptance by some other authors (e.g. Kou and Feng 2018 ; Osman et al 2021 ; Feng et al 2022 ).…”

Didymodon heilongjiangensis (Pottiaceae, Musci), a new species from Heilongjiang Province, China and its phylogenetic position based on molecular data

“…We employed one nuclear (ITS) and two chloroplast markers ( rps 4, trn M‐ trn V), which have been successfully used in previous phylogenetic studies in Didymodon s.lat. which contained most of the species of Didymodon s.str., and which enabled the re‐use of earlier results for in‐context interpretation of new data (Kučera et al 2018, Feng et al 2022, Jiménez et al 2022, Zhang et al 2022). The complete list of sample names and GenBank accession numbers are presented in Table 1 and 2.…”