title: Progenitor-derivative speciation in Pozoa (Apiaceae, Azorelloideae) of the southern Andes.
abstract: OBJECTIVE
  Studies examining patterns and processes of speciation in South America are fewer than in North America and Europe. One of the least well documented processes has been progenitor-derivative speciation. A particularly instructive example occurs in the southern Andes in the genus Pozoa (Apiaceae, Azorelloideae), which consists of only two diploid outcrossing species, the widespread P. coriacea and the geographically and ecologically restricted P. volcanica. This paper tests the hypothesis that the latter species originated from the former through local geographical and ecological isolation by progenitor-derivative speciation.
  
  
  METHODS
  DNA sequences were analysed from Pozoa and the related South American genera Asteriscium, Eremocharis and Gymnophyton from non-coding regions of the plastid genome, ndhF-rpl32 and rpl32-trnL, plus incorporation of previously reported rpl16 intron and trnD-trnT intergenic spacer sequences. Amplified fragment length polymorphism (AFLP) data from 105 individuals in 21 populations throughout the entire range of distribution of the genus were used for estimation of genetic diversity, divergence and SplitsTree network analysis. Ecological factors, including habitat and associated species, were also examined.
  
  
  RESULTS
  Pozoa coriacea is more similar genetically to the outgroup genera, Asteriscium and Eremocharis, than is P. volcanica. At the population level, only P. volcanica is monophyletic, whereas P. coriacea is paraphyletic. Analyses of genetic differentiation among populations and genetic divergence and diversity of the species show highest values in P. coriacea and clear reductions in P. volcanica. Pozoa coriacea occurs in several types of high elevation habitats, whereas P. volcanica is found only in newly formed open volcanic ash zones.
  
  
  CONCLUSIONS
  All facts support that Pozoa represents a good example of progenitor-derivative speciation in the Andes of southern South America.
authors: Department of Systematic and Evolutionary Botany, Faculty Center of Biodiversity, University of Vienna, Austria. patricio.lopez@univie.ac.at
authors: Patricio
authors: P
authors: López
authors: Karin
authors: K
authors: Tremetsberger
authors: Gudrun
authors: G
authors: Kohl
authors: Tod
authors: T
authors: Stuessy
mesh_terms: D019661:Apiaceae / Q000235:genetics*; D018744:DNA, Plant / Q000032:analysis; D004463:Ecology; D019143:Evolution, Molecular; D049810:Genetic Speciation; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D006824:Hybridization, Genetic; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013020:South America
chemical_list: D018744:DNA, Plant