title: Molecular evidence of cryptic speciation, historical range expansion, and recent intraspecific hybridization in the Neotropical seasonal forest tree Cedrela fissilis (Meliaceae).
abstract: Molecular phylogeography can lead to a better understanding of the interaction between past climate events, large-scale vegetation shifts, and the evolutionary history of Neotropical seasonal forests. The endangered timber tree species Cedrela fissilis is associated with seasonal forests and occurs throughout South America. We sampled C. fissilis from 56 sites across the species' range in Brazil and Bolivia and obtained sequence data for nuclear and chloroplast DNA. Most specimens (149 out of 169) exhibited intraindividual polymorphism for the nuclear internal transcribed spacer (ITS). Cloning and an array of complementary sequence analyses indicated that the multiple copies of ITS were functional paralogs--concerted evolution in C. fissilis appeared to be incomplete. Independent Bayesian analyses using either ITS or cpDNA data revealed two separate phylogenetic lineages within C. fissilis that corresponded to populations located in separate geographic regions. The divergence occurred in the Early Pliocene and Late Miocene. We argue that climate-mediated events triggered dispersal events and split ancestral populations into at least two large refugial areas of seasonal forest that were located to the east and west of the present day Cerrado. Upon recent climate amelioration, formerly isolated lineages reconnected and intraspecific hybridization gave rise to intraindividual polymorphism and incomplete concerted evolution in C. fissilis.
authors.affiliation: Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Viçosa, 36570-000 Viçosa, MG, Brazil.
authors.forename: Magali Gonçalves
authors.initials: MG
authors.lastname: Garcia
authors.forename: Roberta Santos
authors.initials: RS
authors.lastname: Silva
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Carniello
authors.forename: Joseph William
authors.initials: JW
authors.lastname: Veldman
authors.forename: Ana Aparecida Bandini
authors.initials: AA
authors.lastname: Rossi
authors.forename: Luiz Orlando
authors.initials: LO
authors.lastname: de Oliveira
mesh_terms: D001499:Bayes Theorem; D031587:Cedrela / Q000235:genetics* / Q000254:growth & development*; D044708:DNA, Concatenated / Q000235:genetics; D021901:DNA, Intergenic / Q000737:chemistry / Q000235:genetics; D030541:Databases, Genetic; D019143:Evolution, Molecular; D005231:Fatty Acids, Unsaturated / Q000235:genetics; D049810:Genetic Speciation; D014644:Genetic Variation; D005843:Geography; D006824:Hybridization, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012621:Seasons; D013020:South America; D013045:Species Specificity; D014197:Trees / Q000235:genetics*; D014329:Tropical Climate
chemical_list: D044708:DNA, Concatenated; D021901:DNA, Intergenic; D005231:Fatty Acids, Unsaturated; C055648:9-(4-chlorophenyl)-7,7-dimethyl-5,8-nonadienoic acid