title: Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids.
abstract: BACKGROUND
  Phenotypic integration among different anatomical parts of the head is a common phenomenon across vertebrates. Interestingly, despite centuries of research into the factors that contribute to the existing variation in brain size among vertebrates, little is known about the role of phenotypic integration in brain size diversification. Here we used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate phenotypic integration across key morphological aspects of the head. Then, while taking the effect of shared ancestry into account, we tested if head shape was associated with brain size while controlling for the potentially confounding effect of feeding strategy.
  
  
  RESULTS
  The shapes of the anterior and posterior parts of the head were strongly correlated, indicating that the head represents an integrated morphological unit in Lake Tanganyika cichlids. After controlling for phylogenetic non-independence, we also found evolutionary associations between head shape, brain size and feeding ecology.
  
  
  CONCLUSIONS
  Geometric morphometrics and phylogenetic comparative analyses revealed that the anterior and posterior parts of the head are integrated, and that head morphology is associated with brain size and feeding ecology in Tanganyikan cichlid fishes. In light of previous results on mammals, our results suggest that the influence of phenotypic integration on brain diversification is a general process.
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden. masahito.tsuboi@ebc.uu.se.
authors.forename: Masahito
authors.initials: M
authors.lastname: Tsuboi
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gonzalez-Voyer
authors.forename: Niclas
authors.initials: N
authors.lastname: Kolm
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology; D023681:Cichlids / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D060106:Lakes; D009929:Organ Size; D010802:Phylogeny; D013636:Tanzania
chemical_list: D004272:DNA, Mitochondrial