title: Evolution of long centromeres in fire ants.
abstract: Centromeres are essential for accurate chromosome segregation, yet sequence conservation is low even among closely related species. Centromere drive predicts rapid turnover because some centromeric sequences may compete better than others during female meiosis. In addition to sequence composition, longer centromeres may have a transmission advantage.
  
  
  
  We report the first observations of extremely long centromeres, covering on average 34 % of the chromosomes, in the red imported fire ant Solenopsis invicta. By comparison, cytological examination of Solenopsis geminata revealed typical small centromeric constrictions. Bioinformatics and molecular analyses identified CenSol, the major centromeric satellite DNA repeat. We found that CenSol sequences are very similar between the two species but the CenSol copy number in S. invicta is much greater than that in S. geminata. In addition, centromere expansion in S. invicta is not correlated with the duplication of CenH3. Comparative analyses revealed that several closely related fire ant species also possess long centromeres.
  
  
  
  Our results are consistent with a model of simple runaway centromere expansion due to centromere drive. We suggest expanded centromeres may be more prevalent in hymenopteran insects, which use haplodiploid sex determination, than previously considered.
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Huang
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Chih-Chi
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Kao
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.|Laboratory of Insect Social Evolution, The Rockefeller University, New York, NY, USA.
authors.forename: Ni-Chen
authors.initials: NC
authors.lastname: Chang
authors.affiliation: Department of Biology, National Changhua University of Education, Changhua, Taiwan.
authors.forename: Chung-Chi
authors.initials: CC
authors.lastname: Lin
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA.|Entomology and Plant Pathology Department, University of Tennessee, Knoxville, TN, USA.
authors.forename: DeWayne
authors.initials: D
authors.lastname: Shoemaker
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan. johnwang@gate.sinica.edu.tw.
authors.forename: John
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D001000:Ants / Q000235:genetics*; D001483:Base Sequence; D002503:Centromere / Q000235:genetics*; D002875:Chromosomes / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics; D056915:DNA Copy Number Variations / Q000235:genetics; D004276:DNA, Satellite / Q000235:genetics; D019143:Evolution, Molecular; D049750:Genome, Insect; D006238:Haploidy
chemical_list: D004276:DNA, Satellite
keywords: Centromere; Centromere drive; Fire ant; Solenopsis geminata; Solenopsis invicta