title: Ecological niche differentiation of polyploidization is not supported by environmental differences among species in a cosmopolitan grass genus.
abstract: •
  
  
  OBJECTIVE
  Polyploidization frequently results in the creation of new plant species, the establishment of which is thought to often be facilitated by ecological niche differentiation from the diploid species. We tested this hypothesis using the cosmopolitan grass genus Phalaris (Poaceae), consisting of 19 species that range from diploid to tetraploid to hexaploid. Specifically, we tested whether (1) polyploids occupy more extreme environments and/or (2) have broader niche breadths and/or (3) whether the polyploid species' distributions indicate a niche shift from diploid species.•
  
  
  METHODS
  We employed a bootstrapping approach using distribution data for each species and eight environmental variables to investigate differences between species in the means, extremes, and breadths of each environmental variable. We used a kernel smoothing technique to quantify niche overlap between species.•
  
  
  RESULTS
  Although we found some support for the three hypotheses for a few diploid-polyploid pairs and for specific environmental variables, none of these hypotheses were generally supported.•
  
  
  CONCLUSIONS
  Our results suggest that these commonly held hypotheses about the effects of polyploidization on ecological distributions are not universally applicable. Correlative biogeographic studies like ours provide a necessary first step for suggesting specific hypotheses that require experimental verification. A combination of genetic, physiological, and ecological studies will be required to achieve a better understanding of the role of polyploidization in niche evolution.
authors.affiliation: Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa.
authors.forename: Vernon
authors.initials: V
authors.lastname: Visser
authors.affiliation: Department of Plant Biology, University of Vermont, Burlington, Vermont 05405 USA.
authors.forename: Jane
authors.initials: J
authors.lastname: Molofsky
mesh_terms: D005075:Biological Evolution; D017753:Ecosystem; D031783:Phalaris / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D063148:Plant Dispersal; D011123:Polyploidy
keywords: Phalaris; Poaceae; canary grass; ecology; niche; polyploidy; whole genome duplication