Metabolic 'engines' of flight drive genome size reduction in birds.
The tendency for flying organisms to possess small genomes has been interpreted as evidence of natural selection acting on the physical size of the genome. Nonetheless, the flight-genome link and its mechanistic basis have yet to be well established by comparative studies within a volant clade. Is there a particular functional aspect of flight such as brisk metabolism, lift production or maneuverability that impinges on the physical genome? We measured genome sizes, wing dimensions and heart, flight muscle and body masses from a phylogenetically diverse set of bird species. In phylogenetically controlled analyses, we found that genome size was negatively correlated with relative flight muscle size and heart index (i.e. ratio of heart to body mass), but positively correlated with body mass and wing loading. The proportional masses of the flight muscles and heart were the most important parameters explaining variation in genome size in multivariate models. Hence, the metabolic intensity of powered flight appears to have driven genome size reduction in birds.
Department of Biology and Museum of Southwestern Biology, University of New Mexico, , Albuquerque, NM 87131, USA, Department of Integrative Biology, University of Guelph, , Guelph, Ontario, Canada , N1G 2W1.
Natalie A
NA
Wright
T Ryan
TR
Gregory
Christopher C
CC
Witt
D000818:Animals; D001717:Birds / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism; D004734:Energy Metabolism / Q000235:genetics*; D005426:Flight, Animal; D016678:Genome; D059646:Genome Size; D006321:Heart / Q000033:anatomy & histology; D009206:Myocardium / Q000378:metabolism; D010802:Phylogeny; D013045:Species Specificity; D014921:Wings, Animal / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology
C-value; flight; flight muscles; genome size; heart index