Species level phylogeny of the genus Cornus (Cornaceae) based on molecular and morphological evidence—implications for taxonomy and Tertiary intercontinental migration

Abstract

DNA sequences were generated for matK and ITS for 68 and 103 samples of Cornus to reconstruct a species level phylogeny of the genus. The results support the monophyly of most subgenera, except subg. Kraniopsis and subg. Cornus. Subgenus Kraniopsis was suggested to exclude C. peruviana from South America and subg. Afrocrania and subg. Sinocornus were nested within subg. Cornus. Four major clades corresponding to groups also recognizable by morphological differences were revealed: the big‐bracted dogwoods (BB) including subg. Cynoxylon, subg. Syncarpea, and subg. Discocrania, the dwarf dogwoods (DW) including subg. Arctocrania, the cornelian cherries (CC) including subg. Cornus, subg. Sinocornus, and subg. Afrocrania, and the blue‐ or white‐fruited dogwoods (BW) including subg. Kraniopsis, subg. Mesomora, and subg. Yinquania. This finding is consistent with previous studies with more limited sampling. The single South American species C. peruviana was found to be sister to the Asian C. oblonga of subg. Yinquania, adding a fourth intercontinental disjunction in the genus that was previously unknown. Species relationships within the subgenera were clearly resolved except for the relatively large subg. Syncarpea and subg. Kraniopsis. Phylogenetic analyses of total evidence combining morphology, matK, ITS, and previously published rbcL and 26S rDNA sequences resolved the relationships among subgenera as (BW(CC(BB, DW))). Biogeographic analyses using DIVA with or without fossils resulted in different inferences of biogeographic history of the genus, indicating the importance of fossil data in biogeographic analyses. The phylogeny based on the total evidence tree including fossils supports an origin and early Tertiary diversification of Cornus in Europe and multiple trans‐Atlantic migrations between Europe and North America by the early Tertiary. It also supports that distribution of the few species in the southern hemisphere was not ancestral, but a result of migration from the north. This evidence rejects a previous hypothesis of a southern hemispheric origin of the genus.

Quantitative and qualitative differences in morphological traits of endocarps revealed between Cornus L. species

“…Wangerin 1910;Hutchinson 1942;Pojarkova 1950;Ferguson 1966;Eyde 1987;Xiang 1987;Murrell 1993Murrell , 1996Hardin and Murrell 1997;Takhtajan 1997;Feng et al 2011). In the current classification, dogwoods are divided into four major clades: the blue-or white-fruited (BW, *35-45 species), the cornelian cherries (CC, 6 species), the big-bracted (BB, *7-12 species), and the dwarf dogwoods (DD 3 herbaceous species) (Xiang et al 1993(Xiang et al , 1996(Xiang et al , 1998(Xiang et al , 2006Fan and Xiang 2001). The blue-or white-fruited dogwoods clade includes three subgenera: Yinquania (Zhu) Murrell, Kraniopsis Raf., and Mesomora Raf.…”

“…To date, there has been little agreement on the number of species and lower taxonomic ranks within the largest subgenus of dogwoods Kraniopsis (Xiang 1989;Murrell 1993;Xiang et al 1996Xiang et al , 2006Xiang and Boufford 2005). However, the taxonomic rank of species belonging to the subg.…”

“…These species have been extensively investigated by Xiang et al (1993Xiang et al ( , 1996Xiang et al ( , 1998Xiang et al ( , 2006, Xiang and Boufford (2005), and Schulz (2011Schulz ( , 2012 using different molecular methods and the classical taxonomic approach. According to Xiang et al (2006), three subclades were recognized within subg.…”

“…According to Xiang et al (2006), three subclades were recognized within subg. Kraniopsis: subclade I, which consists of North American species; subclade II, which contains species from boreal Eurasia, North America, and East Asia; and subclade III, which is represented by a few East Asian species.…”

Phylogeny, Biogeography, and Molecular Dating of Cornelian Cherries (Cornus, Cornaceae): Tracking Tertiary Plant Migration

“…We reconstructed ancestral areas by means of dispersal-vicariance analysis using DIVA 1.1 (Ronquist 1996(Ronquist , 1997, which has been commonly used for reconstructing ancestral areas in biogeographic studies (Xiang et al 2005(Xiang et al , 2006Lang et al 2007;Jeandroz et al 2008). The tree topology resulting from the BEAST analyses was used as the framework for the reconstruction of optimal ancestral distribution in DIVA 1.1.…”