title: High nuclear genetic diversity, high levels of outcrossing and low differentiation among remnant populations of Quercus petraea at the margin of its range in Ireland.
abstract: OBJECTIVE
  Quercus petraea colonized Ireland after the last glaciation from refugia on mainland Europe. Deforestation, however, beginning in Neolithic times, has resulted in small, scattered forest fragments, now covering less than 12,000 ha.
  
  
  METHODS
  Plastid (three fragments) and microsatellite variation (13 loci) were characterized in seven Irish populations sampled along a north-south gradient. Using Bayesian approaches and Wright's F-statistics, the effects of colonization and fragmentation on the genetic structure and mating patterns of extant oak populations were investigated.
  
  
  RESULTS
  All populations possessed cytotypes common to the Iberian Peninsula. Despite the distance from the refugial core and the extensive deforestation in Ireland, nuclear genetic variation was high and comparable to mainland Europe. Low population differentiation was observed within Ireland and populations showed no evidence for isolation by distance. As expected of a marker with an effective population size of one-quarter relative to the nuclear genome, plastid variation indicated higher differentiation. Individual inbreeding coefficients indicated high levels of outcrossing.
  
  
  CONCLUSIONS
  Consistent with a large effective population size in the historical migrant gene pool and/or with high gene flow among populations, high within-population diversity and low population differentiation was observed within Ireland. It is proposed that native Q. petraea populations in Ireland share a common phylogeographic history and that the present genetic structure does not reflect founder effects.
authors.affiliation: Institut für Tierzucht und Genetik, Veterinärmedizinische Universität Wien, Josef Baumann Gasse 1, 1210, Vienna, Austria. g.muir@i122server.vu-wien.ac.at
authors.forename: Graham
authors.initials: G
authors.lastname: Muir
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lowe
authors.forename: Colin C
authors.initials: CC
authors.lastname: Fleming
authors.forename: Claus
authors.initials: C
authors.lastname: Vogl
mesh_terms: D005787:Gene Frequency; D014644:Genetic Variation; D006239:Haplotypes; D007494:Ireland; D018895:Microsatellite Repeats; D018087:Plastids / Q000235:genetics*; D029963:Quercus / Q000235:genetics*