title: Pleistocene climatic oscillations rather than recent human disturbance influence genetic diversity in one of the world's highest treeline species.
abstract: OBJECTIVE
  Biological responses to climatic change usually leave imprints on the genetic diversity and structure of plants. Information on the current genetic diversity and structure of dominant tree species has facilitated our general understanding of phylogeographical patterns.
  
  
  METHODS
  Using amplified fragment length polymorphism (AFLPs), we compared genetic diversity and structure of 384 adults of P. tarapacana with those of 384 seedlings across 32 forest sites spanning a latitudinal gradient of 600 km occurring between 4100 m and 5000 m a.s.l. in Polylepis tarapacana (Rosaceae), one of the world's highest treeline species endemic to the central Andes.
  
  
  RESULTS
  Moderate to high levels of genetic diversity and low genetic differentiation were detected in both adults and seedlings, with levels of genetic diversity and differentiation being almost identical. Four slightly genetically divergent clusters were identified that accorded to differing geographical regions. Genetic diversity decreased from south to north and with increasing precipitation for adults and seedlings, but there was no relationship to elevation.
  
  
  CONCLUSIONS
  Our study shows that, unlike the case for other Andean treeline species, recent human activities have not affected the genetic structure of P. tarapacana, possibly because its inhospitable habitat is unsuitable for agriculture. The current genetic pattern of P. tarapacana points to a historically more widespread distribution at lower altitudes, which allowed considerable gene flow possibly during the glacial periods of the Pleistocene epoch, and also suggests that the northern Argentinean Andes may have served as a refugium for historical populations.
authors.affiliation: Institute of Biology/Geobotany and Botanical Garden, Martin Luther University of Halle-Wittenberg, Am Kirchtor 1, D-06108 Halle/Saale, Germany pengyl09@gmail.com.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Institute of Biology/Geobotany and Botanical Garden, Martin Luther University of Halle-Wittenberg, Am Kirchtor 1, D-06108 Halle/Saale, Germany German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103 Leipzig, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Lachmuth
authors.affiliation: Herbario Nacional de Bolivia (LPB) - Instituto de Ecología-MNHN, Universidad Mayor de San Andrés, Campus Universitario Cota Cota, La Paz, Bolivia.
authors.forename: Silvia C
authors.initials: SC
authors.lastname: Gallegos
authors.affiliation: Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Kessler
authors.affiliation: School of Biological Sciences, Plymouth University, Plymouth PL4 8AA, UK.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Ramsay
authors.affiliation: Instituto de Investigaciones Biológicas y Tecnológicas, Centro de Ecología y Recursos Naturales Renovables (CONICET-Universidad Nacional de Córdoba), Av. Vélez Sarsfield 1611, X5016GCA Córdoba, Argentina.
authors.forename: Daniel
authors.initials: D
authors.lastname: Renison
authors.affiliation: Proyecto de Conservación y Reforestación Sierras de Córdoba, Argentina.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Suarez
authors.affiliation: Institute of Biology/Geobotany and Botanical Garden, Martin Luther University of Halle-Wittenberg, Am Kirchtor 1, D-06108 Halle/Saale, Germany German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103 Leipzig, Germany.
authors.forename: Isabell
authors.initials: I
authors.lastname: Hensen
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D001838:Bolivia; D002677:Chile; D002980:Climate; D014644:Genetic Variation; D046448:Ice Cover; D027824:Rosaceae / Q000235:genetics*; D014197:Trees / Q000235:genetics*
keywords: AFLP; Polylepis tarapacana; central Andes; elevational gradient; latitudinal gradient; phylogeography; post-glacial migration