title: Diversification in the South American Pampas: the genetic and morphological variation of the widespread Petunia axillaris complex (Solanaceae).
abstract: Understanding the spatiotemporal distribution of genetic variation and the ways in which this distribution is connected to the ecological context of natural populations is fundamental for understanding the nature and mode of intraspecific and, ultimately, interspecific differentiation. The Petunia axillaris complex is endemic to the grasslands of southern South America and includes three subspecies: P. a. axillaris, P. a. parodii and P. a. subandina. These subspecies are traditionally delimited based on both geography and floral morphology, although the latter is highly variable. Here, we determined the patterns of genetic (nuclear and cpDNA), morphological and ecological (bioclimatic) variation of a large number of P. axillaris populations and found that they are mostly coincident with subspecies delimitation. The nuclear data suggest that the subspecies are likely independent evolutionary units, and their morphological differences may be associated with local adaptations to diverse climatic and/or edaphic conditions and population isolation. The demographic dynamics over time estimated by skyline plot analyses showed different patterns for each subspecies in the last 100 000 years, which is compatible with a divergence time between 35 000 and 107 000 years ago between P. a. axillaris and P. a. parodii, as estimated with the IMa program. Coalescent simulation tests using Approximate Bayesian Computation do not support previous suggestions of extensive gene flow between P. a. axillaris and P. a. parodii in their contact zone.
authors.affiliation: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PoBox 15053, 91501-970, Porto Alegre, RS, Brazil.
authors.forename: Caroline
authors.initials: C
authors.lastname: Turchetto
authors.affiliation: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PoBox 15053, 91501-970, Porto Alegre, RS, Brazil.
authors.forename: Nelson J R
authors.initials: NJ
authors.lastname: Fagundes
authors.affiliation: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PoBox 15053, 91501-970, Porto Alegre, RS, Brazil.
authors.forename: Ana L A
authors.initials: AL
authors.lastname: Segatto
authors.affiliation: Institute of Plant Sciences, Altenbergrain 21 CH-3013, Bern, Switzerland.
authors.forename: Cris
authors.initials: C
authors.lastname: Kuhlemeier
authors.affiliation: Instituto de Botánica del Nordeste (UNNE-CONICET), Sargento Cabral 2131, Corrientes, 3400, Argentina.
authors.forename: Viviana G
authors.initials: VG
authors.lastname: Solís Neffa
authors.affiliation: Facultad de Agronomía, Universidad de la República, Av. E. Garzón 780, Montevideo, 12900, Uruguay.
authors.forename: Pablo R
authors.initials: PR
authors.lastname: Speranza
authors.affiliation: Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, Porto Alegre, RS, 90610-001, Brazil.
authors.forename: Sandro L
authors.initials: SL
authors.lastname: Bonatto
authors.affiliation: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PoBox 15053, 91501-970, Porto Alegre, RS, Brazil.
authors.forename: Loreta B
authors.initials: LB
authors.lastname: Freitas
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D002980:Climate; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D035264:Flowers / Q000033:anatomy & histology; D014644:Genetic Variation; D005828:Genetics, Population; D065948:Grassland; D006239:Haplotypes; D006824:Hybridization, Genetic; D008957:Models, Genetic; D032306:Petunia / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D017422:Sequence Analysis, DNA; D013020:South America
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant
keywords: CAPS; Petunia axillaris; diversification; floral morphology; grasslands; plastid markers