title: Altered gene expression and ecological divergence in sibling allopolyploids of Dactylorhiza (Orchidaceae).
abstract: BACKGROUND
  Hybridization and polyploidy are potent forces that have regularly stimulated plant evolution and adaptation. Dactylorhiza majalis s.s., D. traunsteineri s.l. and D. ebudensis are three allopolyploid species of a polyploid complex formed through unidirectional (and, in the first two cases, recurrent) hybridization between the widespread diploids D. fuchsii and D. incarnata. Differing considerably in geographical extent and ecological tolerance, the three allopolyploids together provide a useful system to explore genomic responses to allopolyploidization and reveal their role in adaptation to contrasting environments.
  
  
  RESULTS
  Analyses of cDNA-AFLPs show a significant increase in the range of gene expression of these allopolyploid lineages, demonstrating higher potential for phenotypic plasticity than is shown by either parent. Moreover, allopolyploid individuals express significantly more gene variants (including novel alleles) than their parents, providing clear evidence of increased biological complexity following allopolyploidization. More genetic mutations seem to have accumulated in the older D. majalis compared with the younger D. traunsteineri since their respective formation.
  
  
  CONCLUSIONS
  Multiple origins of the polyploids contribute to differential patterns of gene expression with a distinct geographic structure. However, several transcripts conserved within each allopolyploid taxon differ between taxa, indicating that habitat preferences shape similar expression patterns in these independently formed tetraploids. Statistical signals separate several transcripts - some of them novel in allopolyploids - that appear correlated with adaptive traits and seem to play a role favouring the persistence of individuals in their native environments. In addition to stabilizing the allopolyploid genome, genetic and epigenetic alterations are key determinants of adaptive success of the new polyploid species after recurrent allopolyploidization events, potentially triggering reproductive isolation between the resulting lineages.
authors.affiliation: Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg, Austria. ovidiu.paun@univie.ac.at
authors.forename: Ovidiu
authors.initials: O
authors.lastname: Paun
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bateman
authors.forename: Michael F
authors.initials: MF
authors.lastname: Fay
authors.forename: Javier A
authors.initials: JA
authors.lastname: Luna
authors.forename: Justin
authors.initials: J
authors.lastname: Moat
authors.forename: Mikael
authors.initials: M
authors.lastname: Hedrén
authors.forename: Mark W
authors.initials: MW
authors.lastname: Chase
mesh_terms: D000064:Acclimatization; D005075:Biological Evolution; D018076:DNA, Complementary / Q000235:genetics; D017753:Ecosystem; D018506:Gene Expression Regulation, Plant; D029595:Orchidaceae / Q000145:classification / Q000235:genetics*; D011123:Polyploidy
chemical_list: D018076:DNA, Complementary