title: The Genetic Basis of Natural Variation in Drosophila (Diptera: Drosophilidae) Virgin Egg Retention.
abstract: Drosophila melanogaster is able to thrive in harsh northern climates through adaptations in life-history traits and physiological mechanisms that allow for survival through the winter. We examined the genetic basis of natural variation in one such trait, female virgin egg retention, which was previously shown to vary clinally and seasonally. To further our understanding of the genetic basis and evolution of virgin egg retention, we performed a genome-wide association study (GWAS) using the previously sequenced Drosophila Genetic Reference Panel (DGRP) mapping population. We found 29 single nucleotide polymorphisms (SNPs) associated with virgin egg retention and assayed 6 available mutant lines, each harboring a mutation in a candidate gene, for effects on egg retention time. We found that four out of the six mutant lines had defects in egg retention time as compared with the respective controls: mun, T48, Mes-4, and Klp67A Surprisingly, none of these genes has a recognized role in ovulation control, but three of the four genes have known effects on fertility or have high expression in the ovaries. We also found that the SNP set associated with egg retention time was enriched for clinal SNPs. The majority of clinal SNPs had alleles associated with longer egg retention present at higher frequencies in higher latitudes. Our results support previous studies that show higher frequency of long retention times at higher latitude, providing evidence for the adaptive value of virgin egg-retention.
authors.affiliation: Department of Biology, Stanford University, 371 Serra Street, Palo Alto, CA 94305 jakhundzade@g.harvard.edu.|Department of Organismal and Evolutionary Biology, Harvard University, Northwest Labs 248, Cambridge, MA 02138.
authors.forename: Jamilla
authors.initials: J
authors.lastname: Akhund-Zade
authors.affiliation: Department of Biology, Stanford University, 371 Serra Street, Palo Alto, CA 94305.|Department of Biology, University of Virginia, 063A Gilmer Hall, Charlottesville, VA 22903.
authors.forename: Alan O
authors.initials: AO
authors.lastname: Bergland
authors.affiliation: Department of Entomology, Cornell University, 3125 Comstock Hall, Ithaca, 14853 NY.
authors.forename: Sarah O
authors.initials: SO
authors.lastname: Crowe
authors.affiliation: Department of Entomology, Cornell University, 3125 Comstock Hall, Ithaca, 14853 NY.|Department of Molecular Biosciences, University of Kansas, 4055 Haworth Hall, Lawrence, KS 66045.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Unckless
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D005260:Female; D014644:Genetic Variation; D055106:Genome-Wide Association Study; D010063:Ovum / Q000502:physiology*; D010312:Parthenogenesis / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide
keywords: Drosophila Genetics Reference Panel; GWAS; cline; virgin egg retention