title: Structuring evolution: biochemical networks and metabolic diversification in birds.
abstract: Recurrence and predictability of evolution are thought to reflect the correspondence between genomic and phenotypic dimensions of organisms, and the connectivity in deterministic networks within these dimensions. Direct examination of the correspondence between opportunities for diversification imbedded in such networks and realized diversity is illuminating, but is empirically challenging because both the deterministic networks and phenotypic diversity are modified in the course of evolution. Here we overcome this problem by directly comparing the structure of a "global" carotenoid network - comprising of all known enzymatic reactions among naturally occurring carotenoids - with the patterns of evolutionary diversification in carotenoid-producing metabolic networks utilized by birds.
  
  
  
  We found that phenotypic diversification in carotenoid networks across 250 species was closely associated with enzymatic connectivity of the underlying biochemical network - compounds with greater connectivity occurred the most frequently across species and were the hotspots of metabolic pathway diversification. In contrast, we found no evidence for diversification along the metabolic pathways, corroborating findings that the utilization of the global carotenoid network was not strongly influenced by history in avian evolution.
  
  
  
  The finding that the diversification in species-specific carotenoid networks is qualitatively predictable from the connectivity of the underlying enzymatic network points to significant structural determinism in phenotypic evolution.
authors: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA. esmorr@email.arizona.edu.
authors: Erin S
authors: 0000-0002-4487-6915
authors: ES
authors: Morrison
authors: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA.
authors: Alexander V
authors: AV
authors: Badyaev
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000235:genetics*; D002338:Carotenoids / Q000378:metabolism; D014644:Genetic Variation; D023281:Genomics; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D002338:Carotenoids
keywords: Metabolic pathways; Network structure; Phenotypic diversity