title: Hybrid sterility in crosses between two Brazilian sibling species of the Anopheles albitarsis complex.
abstract: BACKGROUND
  Complexes of cryptic species are common in several taxa and this is also the case in the Anopheles genus, a group including all known human malaria vectors. The Anopheles albitarsis complex comprises at least nine cryptic species, some of which are implicated as vectors of human malaria. Several different types of data have been generated for this species complex such as cytogenetics, alloenzymes, morphological and feeding behavioral, hybridization experiments, RAPD-PCR and RFLP and mitochondrial and nuclear markers. Studies focused on its postzygotic isolation are still somewhat rare in the literature despite their importance to understand the speciation process and the level of gene flow potentially occurring among the different sibling species.
  
  
  METHODS
  Hybridization experiments between Anopheles albitarsis s.s. and Anopheles marajoara, as well as backcrosses between hybrids and Anopheles albitarsis s.s., were performed using the induced mating technique. Results were compared to intraspecific crosses. Larva-to-adult viability and sex ratio were also assessed.
  
  
  RESULTS
  Male hybrids show very low insemination rates and nearly complete sterility, apparently due to abnormalities in their reproductive organs. Evidence of partial sterility among the hybrid females was also observed.
  
  
  CONCLUSIONS
  Our data indicated that Anopheles albitarsis s.s. and Anopheles marajoara show a high level of postzygotic isolation with a strong hybrid male sterility. This result is consistent with the Haldane's rule which states that in interspecific crosses the heterogametic sex is the first to be affected. However, the fact that the females are not completely sterile raises the possibility of introgression between these two siblings species.
authors.affiliation: Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil. giglio@ioc.fiocruz.br.
authors.forename: Nathalia Giglio
authors.initials: NG
authors.lastname: Fontoura
authors.affiliation: Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil. saori@ioc.fiocruz.br.
authors.forename: Alejandra Saori
authors.initials: AS
authors.lastname: Araki
authors.affiliation: Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil. reazevedo@ioc.fiocruz.br.
authors.forename: Renata
authors.initials: R
authors.lastname: Van Der Maas Azevedo
authors.affiliation: Instituto de Pesquisas Científicas e Tecnológicas de Estado do Amapá, Macapá, Amapá, Brasil. allangalardo@gmail.com.
authors.forename: Allan Kardec Ribeiro
authors.initials: AK
authors.lastname: Galardo
authors.affiliation: Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil.
authors.forename: Alexandre Afranio
authors.initials: AA
authors.lastname: Peixoto
authors.affiliation: Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil. jbento@ioc.fiocruz.br.|Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ, Brasil. jbento@ioc.fiocruz.br.
authors.forename: José Bento Pereira
authors.initials: JB
authors.lastname: Lima
mesh_terms: D000818:Animals; D000852:Anopheles / Q000502:physiology*; D001938:Brazil; D002678:Chimera; D005260:Female; D006824:Hybridization, Genetic; D007178:Inbreeding; D007246:Infertility; D008297:Male; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D012744:Sex Ratio; D016019:Survival Analysis