Quantitative and molecular genetics of phenotypic variation in the zebra finch

The intraand interspecific diversity of avian beak morphologies is one of the most compelling examples for the power of natural selection acting on a morphological trait. The development and diversification of the beak have also become a textbook example for evolutionary developmental biology, and variation in expression levels of several genes is known to causally affect beak shape. However, until now, no genomic polymorphisms have been identified, which are related to beak morphology in birds. QTL mapping does reveal the location of causal polymorphisms, albeit with poor spatial resolution. Here, we estimate heritability and genetic correlations for beak length, depth and width and perform a QTL linkage analysis for these traits based on 1,404 informative single-nucleotide polymorphisms genotyped in a four-generation pedigree of 992 captive zebra finches (Taeniopygia guttata). Beak size, relative to body size, was sexually dimorphic (larger in males). Heritability estimates ranged from 0.47 for beak length to 0.74 for beak width. QTL mapping revealed four to five regions of significant or suggestive genome-wide linkage for each of the three beak dimensions (nine different regions in total). Eight out of 11 genes known to influence beak morphology are located in these nine peak regions. Five QTL do not cover known candidates demonstrating that yet unknown genes or regulatory elements may influence beak morphology in the zebra finch. Published as: Knief U, H Schielzeth, B Kempenaers, H Ellegren, W Forstmeier 2012: QTL and quantitative genetic analysis of beak morphology reveals patterns of standing genetic variation in an Estrildid finch. Molecular Ecology 21: 3704–3717. Molecular Ecology (2012) 21, 3704–3717 doi: 10.1111/j.1365-294X.2012. 05661.x QTL and quantitative genetic analysis of beak morphology reveals patterns of standing genetic variation in an Estrildid finch ULRICH KNIEF,* HOLGER SCHIELZETH,†‡ BART KEMPENAERS,* HANS ELLEGREN† and WOLFGANG FORSTMEIER* *Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Eberhard-Gwinner-Str. , 82319 Seewiesen, Germany, †Department of Evolutionary Biology, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden Corresponde E-mail: uknie Current add Bielefeld Uni Germany. Abstract The intraand interspecific diversity of avian beak morphologies is one of the most compelling examples for the power of natural selection acting on a morphological trait. The development and diversification of the beak have also become a textbook example for evolutionary developmental biology, and variation in expression levels of several genes is known to causally affect beak shape. However, until now, no genomic polymorphisms have been identified, which are related to beak morphology in birds. QTL mapping does reveal the location of causal polymorphisms, albeit with poor spatial resolution. Here, we estimate heritability and genetic correlations for beak length, depth and width and perform a QTL linkage analysis for these traits based on 1404 informative singlenucleotide polymorphisms genotyped in a four-generation pedigree of 992 captive zebra finches (Taeniopygia guttata). Beak size, relative to body size, was sexually dimorphic (larger in males). Heritability estimates ranged from 0.47 for beak length to 0.74 for beak width. QTL mapping revealed four to five regions of significant or suggestive genomewide linkage for each of the three beak dimensions (nine different regions in total). Eight out of 11 genes known to influence beak morphology are located in these nine peak regions. Five QTL do not cover known candidates demonstrating that yet unknown genes or regulatory elements may influence beak morphology in the zebra finch.