Biogeographic origins of southern African Silene (Caryophyllaceae)

• Silene (Caryophyllaceae) is distributed predominantly in the northern Hemisphere, where it is most diverse around the Mediterranean Basin. The genus is also well represented in North Africa, extending into tropical, subSaharan and southern Africa. Eight native species are recognized in southern Africa, taxonomically placed in two sections: Elisanthe and Silene s.l. Although the taxonomy of the southern African taxa has recently been revised, their phylogenetic relationships and biogeographic history remain unclear. This study aims to infer the phylogenetic position and geographic origins of the southern African taxa. We generated DNA sequences of nuclear and plastid loci from several individuals belonging to all eight species of Silene recognized from southern Africa, and combined our DNA sequences with existing data representing species from major clades (i.e. sections) based on the recently revised Silene infrageneric taxonomy. We used a Bayesian coalescent species tree continuous diffusion approach to co-estimate the species tree and the ancestral areas of representative members of the genus. Our results show that the perennial southern African members of section Elisanthe form a strongly-supported clade with the Eurasian annual S. noctiflora and the Central Asian perennial S. turkestanica. The rest of the perennial species form a strongly-supported clade together with the annual S. aethiopica, which is nested in a larger Mediterranean clade comprising mostly annual species classified in section Silene s.l. Estimates of ancestral areas indicate a late Pleistocene dispersal to southern Africa from central and East Africa for the sub-Saharan members of section Silene s.l. The Elisanthe clade is inferred to have colonized southern Africa through longdistance dispersal from Eurasia during the late Pleistocene. Our findings support the hypothesis of a relatively recent colonization into southern Africa resulting from two independent dispersal events during the Pleistocene.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Biogeography

Relaxed random wa l k

Elisanthe

BEAST

Phylogeny

Brownian diffusion

Species tree

historical biogeography

phylogenetic-relationships

taxonomic revision

evolution

flora

diversification

dispersal

siphonomorpha

afrotemperate

hybridization

Biochemistry & Molecular Biology

Evolutionary Biology

Heredity

Publikations- och innehållstyp

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