title: Tempo and mode of flower color evolution.
abstract: •
  
  
  OBJECTIVE
  Flower color is one of the best-studied floral traits in terms of its genetic basis and ecological significance, yet few studies have examined the processes that shape its evolution across deep timescales. Advances in comparative methods along with larger phylogenies for floral radiations offer new opportunities for investigating the macroevolution of flower color.•
  
  
  METHODS
  We examined the tempo and mode of flower color evolution in four clades (Antirrhineae, Iochrominae, Loeselieae, Quamoclit) using models that incorporate trait transitions and lineage diversification. Focusing on floral anthocyanin pigmentation, we estimated rates of gain and loss of pigmentation and tested whether these changes occur predominantly through anagenesis or cladogenesis.•
  
  
  RESULTS
  We found that the tempo of pigment gains and losses varied significantly across the clades and that the rates of change were often asymmetrical, favoring gains over losses. The mode of color shifts tended to be cladogenetic, particularly for gains of color; however, this trend was not significant.•
  
  
  CONCLUSIONS
  Given that all flowering plants share the same pathway for producing anthocyanins, the marked variation in the tempo of transitions across the four groups suggests differences in the selective forces acting on floral pigmentation. These ecological and physiological factors, together with genetic basis for color, may also explain the bias toward gains of floral anthocyanins. Estimates for cladogenetic and anagenetic rates suggest that color transitions can occur through both modes, although testing their relative importance will require larger datasets.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309 USA.
authors.forename: Stacey D
authors.initials: SD
authors.lastname: Smith
authors.affiliation: Department of Ecology, Evolution & Behavior, University of Minnesota, St Paul, Minnesota 55108 USA.
authors.forename: Emma E
authors.initials: EE
authors.lastname: Goldberg
mesh_terms: D000872:Anthocyanins / Q000378:metabolism; D005075:Biological Evolution; D035264:Flowers / Q000235:genetics* / Q000502:physiology; D049810:Genetic Speciation; D019684:Magnoliopsida / Q000235:genetics* / Q000502:physiology; D008954:Models, Biological; D010641:Phenotype; D010860:Pigments, Biological / Q000235:genetics* / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D010860:Pigments, Biological
keywords: anagenetic; anthocyanins; cladogenetic; diversification; floral color; macroevolution; pigmentation; speciation; transition rate