Into Africa: Molecular phylogenetics and historical biogeography of sub-Saharan African woodferns (Dryopteris).
OBJECTIVE
Our goal was to infer the phylogenetic relationships and historical biogeography of the genusDryopteriswith a focus on taxa in sub-Saharan Africa and neighboring islands. In general, little is known about the relationships between African fern species and their congeners in other geographic regions, and our aim was to determine whether the sub-Saharan African species ofDryopterisare monophyletic and evolved within Africa or arrived there via repeated dispersals into Africa from other regions.


METHODS
We obtained sequence data for five chloroplast markers from 214 species ofDryopterisand 18 outgroups. We performed phylogenetic and molecular dating analyses using a Bayesian relaxed clock method in BEAST with fossil and secondary calibration points and estimated ancestral ranges for the genus globally by comparing multiple models in BioGeoBEARS.


RESULTS
We found that 22 of 27 accessions of sub-Saharan AfricanDryopterisbelong to a large clade of 31 accessions that also includes taxa from Indian and Atlantic Ocean islands. Additional accessions of taxa from our regions of interest have Asian, Hawaiian, European, or North American species as their closest relatives.


CONCLUSIONS
The majority of sub-Saharan AfricanDryopterisspecies are descended from a shared common ancestor that dispersed to Africa from Asia approximately 10 Ma. There have been subsequent dispersal events from the African mainland to islands in the Atlantic and Indian Oceans, including Madagascar. Several additional species are estimated to have descended from ancestors that reached Africa via separate events over the last roughly 20 million years.
Department of Biology, University of Florida, Gainesville, Florida 32611 USA emilysessa@ufl.edu.|Genetics Institute, University of Florida, Gainesville, Florida 32611 USA.
Emily B
EB
Sessa
Finnish Museum of Natural History, University of Helsinki 00014 Finland.
Aino
A
Juslén
Finnish Museum of Natural History, University of Helsinki 00014 Finland.
Henry
H
Väre
Department of Biology, University of Florida, Gainesville, Florida 32611 USA.
Sally M
SM
Chambers
D017954:Africa South of the Sahara; D001499:Bayes Theorem; D032492:Dryopteris / Q000145:classification / Q000235:genetics* / Q000502:physiology; D019143:Evolution, Molecular; D005580:Fossils; D010802:Phylogeny; D058974:Phylogeography; D063148:Plant Dispersal; D017422:Sequence Analysis, DNA
Africa; Dryopteridaceae; ancestral range estimation; ferns; historical biogeography; long-distance dispersal; molecular dating