Folia Geobotanica

, Volume 47, Issue 4, pp 441–460

Geographical Distribution of Diploid and Tetraploid Cytotypes of Thymus sect. Mastichina (Lamiaceae) in the Iberian Peninsula, Genome Size and Evolutionary Implications

  • Verónica Girón
  • Teresa Garnatje
  • Joan Vallès
  • Ernesto Pérez-Collazos
  • Pilar Catalán
  • Benito Valdés
Article

DOI: 10.1007/s12224-012-9126-0

Cite this article as:
Girón, V., Garnatje, T., Vallès, J. et al. Folia Geobot (2012) 47: 441. doi:10.1007/s12224-012-9126-0

Abstract

The occurrence of diploid and tetraploid cytotypes in Thymus section Mastichina (Lamiaceae) was investigated by chromosome counting and flow cytometric measurements of DNA content. To cover the entire native distribution of the section across the Iberian Peninsula, plant material was sampled from 29 populations, representing all three taxa (Thymus albicans, T. mastichina subsp. mastichina and T. mastichina subsp. donyanae). We provide first estimates of genome size for taxa of this section. Analyses revealed the existence of new cytotypes in T. mastichina subsp. mastichina (2n = 2x = 28, 30) and confirmed the existence of previous ones (2n = 4x = 56, 58, 60). We also confirmed the presence of exclusively diploid cytotypes (2n = 2x = 30) in the southwestern Iberian endemics T. albicans and T. mastichina subsp. donyanae. We conclude that the southwestern Iberian Peninsula acted as a Pleistocene glacial refugium that may have permitted speciation processes within this section. Several hypotheses concerning these processes and the origin and distribution of the studied taxa are discussed.

Keywords

Chromosome numbersEndemismFlow cytometryGenome evolutionKaryologyPloidy level

Copyright information

© Institute of Botany, Academy of Sciences of the Czech Republic 2012

Authors and Affiliations

  • Verónica Girón
    • 1
  • Teresa Garnatje
    • 2
  • Joan Vallès
    • 3
  • Ernesto Pérez-Collazos
    • 4
  • Pilar Catalán
    • 4
  • Benito Valdés
    • 1
  1. 1.Departamento de Biología Vegetal y EcologíaUniversidad de SevillaSevillaSpain
  2. 2.Institut Botànic de Barcelona (IBB-CSIC-ICUB)BarcelonaSpain
  3. 3.Laboratori de Botànica, Facultat de FarmàciaUniversitat de BarcelonaBarcelonaSpain
  4. 4.Departamento de Agricultura y Economía Agraria. Escuela Politécnica Superior de HuescaUniversidad de ZaragozaHuescaSpain