title: Genome size variation affects song attractiveness in grasshoppers: evidence for sexual selection against large genomes.
abstract: Genome size is largely uncorrelated to organismal complexity and adaptive scenarios. Genetic drift as well as intragenomic conflict have been put forward to explain this observation. We here study the impact of genome size on sexual attractiveness in the bow-winged grasshopper Chorthippus biguttulus. Grasshoppers show particularly large variation in genome size due to the high prevalence of supernumerary chromosomes that are considered (mildly) selfish, as evidenced by non-Mendelian inheritance and fitness costs if present in high numbers. We ranked male grasshoppers by song characteristics that are known to affect female preferences in this species and scored genome sizes of attractive and unattractive individuals from the extremes of this distribution. We find that attractive singers have significantly smaller genomes, demonstrating that genome size is reflected in male courtship songs and that females prefer songs of males with small genomes. Such a genome size dependent mate preference effectively selects against selfish genetic elements that tend to increase genome size. The data therefore provide a novel example of how sexual selection can reinforce natural selection and can act as an agent in an intragenomic arms race. Furthermore, our findings indicate an underappreciated route of how choosy females could gain indirect benefits.
authors.affiliation: Department of Evolutionary Biology, Bielefeld University, 33615 Bielefeld, Germany. holger.schielzeth@uni-bielefeld.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Schielzeth
authors.forename: Corinna
authors.initials: C
authors.lastname: Streitner
authors.forename: Ulrike
authors.initials: U
authors.lastname: Lampe
authors.forename: Alexandra
authors.initials: A
authors.lastname: Franzke
authors.forename: Klaus
authors.initials: K
authors.lastname: Reinhold
mesh_terms: D000818:Animals; D059646:Genome Size; D049750:Genome, Insect; D006110:Grasshoppers / Q000235:genetics* / Q000502:physiology; D008297:Male; D052586:Mating Preference, Animal; D012641:Selection, Genetic; D014828:Vocalization, Animal
keywords: C-value enigma; coevolutionary arms race; genome size evolution; honest signaling; indirect genetic benefits; mate choice; selfish genetic elements