title: Effects of ploidy and sex-locus genotype on gene expression patterns in the fire ant Solenopsis invicta.
abstract: Males in many animal species differ greatly from females in morphology, physiology and behaviour. Ants, bees and wasps have a haplodiploid mechanism of sex determination whereby unfertilized eggs become males while fertilized eggs become females. However, many species also have a low frequency of diploid males, which are thought to develop from diploid eggs when individuals are homozygous at one or more sex determination loci. Diploid males are morphologically similar to haploids, though often larger and typically sterile. To determine how ploidy level and sex-locus genotype affect gene expression during development, we compared expression patterns between diploid males, haploid males and females (queens) at three developmental timepoints in Solenopsis invicta. In pupae, gene expression profiles of diploid males were very different from those of haploid males but nearly identical to those of queens. An unexpected shift in expression patterns emerged soon after adult eclosion, with diploid male patterns diverging from those of queens to resemble those of haploid males, a pattern retained in older adults. The finding that ploidy level effects on early gene expression override sex effects (including genes implicated in sperm production and pheromone production/perception) may explain diploid male sterility and lack of worker discrimination against them during development.
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand.
authors.forename: Mingkwan
authors.initials: M
authors.lastname: Nipitwattanaphon
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Biodiversity Research Center, Academia Sinica, Nangang Taipei 115, Taiwan, Republic of China.
authors.forename: John
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Entomology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Ross
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland.
authors.forename: Oksana
authors.initials: O
authors.lastname: Riba-Grognuz
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland School of Biological and Chemical Sciences, Queen Mary University London, London E1 4NS, UK.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Wurm
authors.affiliation: Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Chitsanu
authors.initials: C
authors.lastname: Khurewathanakul
authors.affiliation: Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland laurent.keller@unil.ch.
authors.forename: Laurent
authors.initials: L
authors.lastname: Keller
mesh_terms: D000818:Animals; D001000:Ants / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D008297:Male; D011003:Ploidies; D019849:Sex Determination Processes
keywords: Hymenoptera; complementary sex-determination; diploid male; doublesex; microarray; sex determination