title: Species-level phylogeny, fruit evolution and diversification history of Geranium (Geraniaceae).
abstract: The cosmopolitan genus Geranium L. (Geraniaceae) consists of c. 350 species distributed in temperate habitats worldwide, with most of its diversity concentrated in the Mediterranean region. Unlike other genera in Geraniaceae, the species of Geranium present contrasting seed discharge syndromes, i.e. the 'Erodium-type' (ET), the 'carpel-projection type' (CP), the 'seed-ejection type' (SE), and the 'inoperative type' (IT), which have been used to delimit major groups within the genus. However, phylogenetic relationships within Geranium are unknown and so is the evolution of the different seed discharge mechanisms. Here, we used a calibrated multispecies coalescent approach to infer the species-level phylogeny and divergence times of the genus based on chloroplast (rbcL, trnL-trnF) and nuclear (ITS) DNA sequences. Our sampling represents most of the morphological variation described in the genus. We reconstruct the evolution of the seed discharge mechanism using ancestral state reconstruction (ASR) techniques on the multispecies coalescent tree, and assess the association between fruit type evolution and species diversification using stochastic birth-death and trait-dependent diversification models. Finally, we reconstruct the early biogeographic history of the genus using discrete and continuous biogeographic analyses of species distribution centroids, including fossil evidence and tip dates. Our results show that fruit type is homoplasious and that the classification based on fruit type in Geranium is artificial. The taxonomy and putative apomorphic characters for Geranium are discussed. ASR of the fruit characters suggests that ET may represent the ancestral state in Geranium and from which CP originated twice, IT presumably once, and SE twice. The independent appearance of the SE syndrome is in both cases associated with increases in diversification rates in the genus. The biogeographic analysis centers the origin and early 10Ma diversification of Geranium on the Mediterranean region. The evolution of seed discharge mechanism about 5Ma might have allowed the species of Geranium to increase in geographic range and to ultimately, diversify.
authors.affiliation: Monrads gate 21a, 0564 Oslo, Norway. Electronic address: thmsmrcssn@gmail.com.
authors.forename: Thomas
authors.initials: T
authors.lastname: Marcussen
authors.affiliation: INRA, UMR 1062 CBGP (INRA, IRD, CIRAD, Montpellier SupAgro), The Center for Biology and Management of Populations (CBGP), Avenue du Campus Agropolis, 34980 Montferrier-sur-Lez, France. Electronic address: asanchezmeseguer@gmail.com.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Meseguer
mesh_terms: D001483:Base Sequence; D001499:Bayes Theorem; D044822:Biodiversity; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005638:Fruit / Q000033:anatomy & histology*; D031315:Geranium / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics; D008954:Models, Biological; D010802:Phylogeny; D058974:Phylogeography; D012639:Seeds / Q000033:anatomy & histology; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant; D004275:DNA, Ribosomal
keywords: Ancestral state reconstruction; Biogeography; Diversification rate; Fruit evolution; Geranium; Multispecies coalescent