title: The evolutionary dynamics of haplodiploidy: Genome architecture and haploid viability.
abstract: Haplodiploid reproduction, in which males are haploid and females are diploid, is widespread among animals, yet we understand little about the forces responsible for its evolution. The current theory is that haplodiploidy has evolved through genetic conflicts, as it provides a transmission advantage to mothers. Male viability is thought to be a major limiting factor; diploid individuals tend to harbor many recessive lethal mutations. This theory predicts that the evolution of haplodiploidy is more likely in male heterogametic lineages with few chromosomes, as genes on the X chromosome are often expressed in a haploid environment, and the fewer the chromosome number, the greater the proportion of the total genome that is X-linked. We test this prediction with comparative phylogenetic analyses of mites, among which haplodiploidy has evolved repeatedly. We recover a negative correlation between chromosome number and haplodiploidy, find evidence that low chromosome number evolved prior to haplodiploidy, and that it is unlikely that diplodiploidy has reevolved from haplodiploid lineages of mites. These results are consistent with the predicted importance of haploid male viability.
authors.affiliation: Department of Biology, University of Texas, Arlington, Box 19498, Arlington, Texas, 76019.
authors.forename: Heath
authors.initials: H
authors.lastname: Blackmon
authors.affiliation: Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, 36849.
authors.forename: Nate B
authors.initials: NB
authors.lastname: Hardy
authors.affiliation: School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, EH9 3JT, United Kingdom. laura.ross@ed.ac.uk.
authors.forename: Laura
authors.initials: L
authors.lastname: Ross
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004171:Diploidy; D005260:Female; D006238:Haploidy; D008297:Male; D008925:Mites / Q000235:genetics*; D008957:Models, Genetic; D010802:Phylogeny; D012098:Reproduction / Q000235:genetics*
keywords: Acari; chromosomal evolution; haplodiploidy; reproductive strategies; sex determination