Biogeography ofPlagiochila(Hepaticae): natural species groups span several floristic kingdoms

Abstract

Aim This paper presents a synthesis of our recent results regarding the biogeography of Plagiochila using a molecular approach, and documents intercontinental ranges within this largest genus of the hepatics. Methods A maximum likelihood analysis of sixty‐one nrITS sequences of Plagiochila was performed and the molecular topology obtained was compared with morphological, phytochemical and geographical data. Results Our molecular data set allowed the identification of eleven Plagiochila sections, the majority of which cover at least two floristic kingdoms. Seven sections have species in Europe (sect. Arrectae, Carringtoniae, Fuscoluteae, Glaucescentes, Plagiochila, Rutilantes, Vagae). Plagiochila species from Atlantic Europe are usually close to or conspecific with neotropical taxa, whereas species widespread in Europe are closely related to Asian ones and not to those in the Neotropics. Plagiochila sect. Arrectae represents a neotropical – Atlantic European clade. The section is not closely related – as has often been suggested – to the morphologically similar sect. Zonatae from Asia and western North America. Sequence data show that the African P. integerrima and the neotropical P. subplana are members of the Asian sect. Cucullatae (sect. Ciliatae, syn. nov.), which becomes pantropical in distribution. An ITS sequence of P. boryana from Uganda confirms the Afro‐American range of the primarily neotropical sect. Hylacoetes. Similarities in sporophyte morphology between the sect. Cucullatae and sect. Hylacoetes are the result of parallel evolution. Main conclusions Our results indicate that intercontinental ranges at section and species level are common in Plagiochila. Carl's (1931) subdivision of Plagiochila into sections restricted to one floristic kingdom is outdated. Biogeographical patterns in Plagiochila are not dissimilar to those of other groups of bryophytes but elucidation of the geographical ranges of the taxa requires a molecular approach. Contrary to earlier belief, most Plagiochila species from Atlantic Europe do not have close relatives in Asia but are conspecific with or closely related to species from tropical America.

Recent divergence, intercontinental dispersal and shared polymorphism are shaping the genetic structure of amphi‐Atlantic peatmoss populations

“…Accumulating population genetic, phylogenetic and experimental evidence suggests that intercontinental distribution ranges of many bryophyte species are better explained by recent long‐distance dispersal than by continental drift (Van der Velde et al . 2001; Groth et al . 2003; Muñoz et al .…”

Intercontinental distribution of Plagiochila corrugata (Plagiochilaceae, Hepaticae) inferred from nrDNA ITS sequences and morphology

“…sect. Hylacoetes (Heinrichs, 2002; Groth et al ., 2003), which occurs in Bolivia, Brazil, Uganda, Tanzania and on the Mascarenes. The distribution of P. corrugata is not unique among the Afro‐American disjuncts.…”

“…25 ITS1‐, 5.8S‐, and ITS2 rDNA sequences from Heinrichs (2002), Heinrichs et al . (2002a), Groth et al . (2003), Groth et al .…”

“…Vagae and the closely related Plagiochila sects Cucullatae Schiffn., Plagiochila , and Zonatae (e.g. Groth & Heinrichs, 2003; Groth et al ., 2003) were sampled. Plagiochila aerea Taylor and P. fuscolutea Taylor ( P. sect.…”

“…Plagiochila aerea Taylor and P. fuscolutea Taylor ( P. sect. Fuscoluteae Carl) were chosen as outgroup, according to the results of Groth et al . (2003).…”