ABSTRACT
Lycophytes are an ancient clade of the non-flowering vascular plants with chromosome numbers that vary from tens to hundreds. They are an excellent study system for examining whole-genome duplications (WGDs), or polyploidization, in spore-dispersed vascular plants. However, a lack of genome sequence data limits the reliable detection of very ancient WGDs, small-scale duplications (SSDs), and recent WGDs. Here, we integrated phylogenomic analysis and the distribution of synonymous substitutions per synonymous sites (Ks) of the transcriptomes of 13 species of lycophytes to identify, locate, and date multiple WGDs in the lycophyte family Lycopodiaceae. Additionally, we examined the genus Phlegmariurus for signs of genetic discordance, which can provide valuable insight into the underlying causes of such conflict (e.g., hybridization, incomplete lineage sorting, or horizontal gene transfer).We found strong evidence that two WGD events occurred along the phylogenetic backbone of Lycopodiaceae, with one occurring in the common ancestor of extant Phlegmariurus (Lycopodiaceae) approximately 22-23 million years ago (Mya) and the other occurring in the common ancestor of Lycopodiaceae around 206-214 Mya. Interestingly, we found significant genetic discordance in the genus Phlegmariurus, indicating that the genus has a complex evolutionary history. This study provides molecular evidence for multiple WGDs in Lycopodiaceae and offers phylogenetic clues to the evolutionary history of Lycopodiaceae.
ABSTRACT
Dipterisshenzhenensis, a new species of ferns from Shenzhen, Guangdong, southern China, is identified and described. It closely resembles D.chinensis but possesses several unique traits, such as long rhizome scales, castaneous stipe, and abaxially pale fronds with two fan-shaped fronds connected by a broad wing. Molecular evidence showed that D.shenzhenensis is allied to D.conjugata, whereas it has morphologically significant differences (P < 0.05) on the basis of quantitative trait statistical analysis. Overall, the morphological evidence, taken together with the result of cpDNA indicated that D.shenzhenensis is a distinct species.
ABSTRACT
Although taxonomists target the remote wild regions to discover new species, taxa lacking a comprehensive and modern systematic treatment may be the new hotspot for biodiversity discovery. The development of molecular systematics integrated with microscopic observation techniques has greatly improved the ability of taxonomists to identify species correctly. Vittariacentrochinensis Ching ex J.F. Cheng, regarded as a synonym of Haplopterisfudzinoi (Makino) E.H.Crane, remained hidden from the eyes of fern taxonomists for more than 20 years. Herein, we collected several population samples of V.centrochinensis by performing molecular phylogenetic analysis of five cpDNA regions (rbcL, atpA, matK, ndhF, and trnL-trnF) and through micromophological observation of specimens which differs from H.fudzinoi by lamina width and exospores. Considering the differences in morphology, geographical range, and genetic distance between these two species, we formally recognized V.centrochinensis as an authentic species and proposed a new combination Haplopteriscentrochinensis (Ching ex J.F.Cheng) Y.H.Yan, Z.Y.Wei & X.C.Zhang, comb. nov. Our findings demonstrate that several taxa in synonyms are missing, and nowadays taxonomy should also include re-evaluation of the past taxonomy.
