title: Increased genetic differentiation but no reduced genetic diversity in peripheral vs. central populations of a steppe grass.
abstract: OBJECTIVE
  Intraspecific genetic variation is essential for the performance and evolution of species. Populations at a species' geographic range periphery receive considerable attention in biogeography and conservation because they are smaller and spatially more isolated than central populations, a pattern expected to lead to higher genetic differentiation and lower within-population genetic diversity. We tested these predictions in central and peripheral populations of the Eurasian steppe grass Stipa capillata.
  
  
  METHODS
  We analyzed AFLP fingerprint patterns in 319 individuals from 20 large and abundant populations in the core, in Kazakhstan, and 23 small and isolated populations at the periphery, in Central Europe. We calculated different genetic diversity estimates and assessed genetic differentiation among populations by examining F(ST) values, a neighbor-net network, and an AMOVA.
  
  
  RESULTS
  As expected, genetic differentiation among populations was significantly larger at the range periphery (F(ST) = 0.415) than in the range core (F(ST) = 0.164). In contrast to predictions, however, we found similarly low genetic diversity within central (proportion of polymorphic bands = 21.9%) and peripheral (20%) populations.
  
  
  CONCLUSIONS
  Higher genetic differentiation in the small and spatially isolated peripheral populations is likely driven by genetic drift and reduced gene flow due to a complex landscape structure and the abandonment of traditional management regimes. With regard to unchanged genetic diversity, it appears that life-history traits like longevity or sufficiently large population sizes could allow S. capillata to escape deleterious effects at the range edge.
authors.affiliation: Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, D-06108 Halle, Germany. viktoria.wagner@botanik.unihalle.de
authors.forename: Viktoria
authors.initials: V
authors.lastname: Wagner
authors.forename: Walter
authors.initials: W
authors.lastname: Durka
authors.forename: Isabell
authors.initials: I
authors.lastname: Hensen
mesh_terms: D017753:Ecosystem; D005060:Europe; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D007623:Kazakhstan; D016014:Linear Models; D010802:Phylogeny; D006109:Poaceae / Q000235:genetics*