title: Pollen dispersal and breeding structure in a hawkmoth-pollinated Pampa grasslands species Petunia axillaris (Solanaceae).
abstract: OBJECTIVE
  The evolution of selfing is one of the most common transitions in flowering plants, and this change in mating pattern has important systematic and ecological consequences because it often initiates reproductive isolation and speciation. Petunia axillaris (Solanaceae) includes three allopatric subspecies widely distributed in temperate South America that present different degrees of self-compatibity and incompatibility. One of these subspecies is co-distributed with P. exserta in a restricted area and presents a complex, not well-understood mating system. Artificial crossing experiments suggest a complex system of mating in this sympatric area. The main aims of this study were to estimate the pollen dispersal distance and to evaluate the breeding structure of P. axillaris subsp. axillaris, a hawkmoth-pollinated taxon from this sympatric zone.
  
  
  METHODS
  Pollen dispersal distance was compared with nearest-neighbours distance, and the differentiation in the pollen pool among mother plants was estimated. In addition, the correlation between genetic differentiation and spatial distance among plants was tested. All adult individuals (252) within a space of 2800 m(2) and 15 open-pollinated progeny (285 seedlings) were analysed. Genetic analyses were based on 12 polymorphic microsatellite loci.
  
  
  RESULTS
  A high proportion of self-pollination was found, indicating a mixed-mating system. The maximum pollen dispersal distance was 1013 m, but most pollination events (96 %) occurred at a distance of 0 m, predominantly in an inbreeding system. Both parents among sampled individuals could be identifed in 60-85 % of the progeny.
  
  
  CONCLUSIONS
  The results show that most pollen dispersal in the hawkmoth-pollinated P. axillaris subsp. axillaris occurs within populations and there is a high proportion of inbreeding. This mating system appears to favour species integrity in a secondary contact zone with the congener species P. exserta.
authors: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil.
authors: Caroline
authors: C
authors: Turchetto
authors: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil.
authors: Jacqueline S
authors: JS
authors: Lima
authors: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil.
authors: Daniele M
authors: DM
authors: Rodrigues
authors: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil.
authors: Sandro L
authors: SL
authors: Bonatto
authors: Laboratory of Molecular Evolution, Department of Genetics, Universidade Federal do Rio Grande do Sul, PO Box 15053, Porto Alegre, Brazil, Laboratory of Genetic Diversity, Universidade Federal de Goiás, PO Box 131, 74001-970 Goiania, GO, Brazil and Laboratory of Genomic and Molecular Biology, Pontifícia Universidade Católica do Rio Grande do Sul, Ipiranga 6681, 90610-001 Porto Alegre, RS, Brazil loreta.freitas@ufrgs.br.
authors: Loreta B
authors: LB
authors: Freitas
mesh_terms: D000818:Animals; D001947:Breeding; D056426:Genetic Loci; D005828:Genetics, Population; D065948:Grassland; D007178:Inbreeding; D018895:Microsatellite Repeats / Q000235:genetics; D008954:Models, Biological; D009036:Moths / Q000502:physiology*; D011058:Pollen / Q000235:genetics / Q000502:physiology*; D054817:Pollination / Q000502:physiology*; D058614:Seed Dispersal / Q000502:physiology*; D013045:Species Specificity
keywords: P. exserta; Pampas; Petunia axillaris; Pollen dispersal; Solanaceae; breeding structure; gene flow; genetic structure; hawkmoth pollination; inbreeding; microsatellites; selfing