title: The persistence of facultative parthenogenesis in Drosophila albomicans.
abstract: Parthenogenesis has evolved independently in more than 10 Drosophila species. Most cases are tychoparthenogenesis, which is occasional or accidental parthenogenesis in normally bisexual species with a low hatching rate of eggs produced by virgin females; this form is presumed to be an early stage of parthenogenesis. To address how parthenogenesis and sexual reproduction coexist in Drosophila populations, we investigated several reproductive traits, including the fertility, parthenogenetic capability, diploidization mechanisms, and mating propensity of parthenogenetic D. albomicans. The fertility of mated parthenogenetic females was significantly higher than that of virgin females. The mated females could still produce parthenogenetic offspring but predominantly produced offspring by sexual reproduction. Both mated parthenogenetic females and their parthenogenetic-sexual descendants were capable of parthenogenesis. The alleles responsible for parthenogenesis can be propagated through both parthenogenesis and sexual reproduction. As diploidy is restored predominantly by gamete duplication, heterozygosity would be very low in parthenogenetic individuals. Hence, genetic variation in parthenogenetic genomes would result from sexual reproduction. The mating propensity of females after more than 20 years of isolation from males was decreased. If mutations reducing mating propensities could occur under male-limited conditions in natural populations, decreased mating propensity might accelerate tychoparthenogenesis through a positive feedback mechanism. This process provides an opportunity for the evolution of obligate parthenogenesis. Therefore, the persistence of facultative parthenogenesis may be an adaptive reproductive strategy in Drosophila when a few founders colonize a new niche or when small populations are distributed at the edge of a species' range, consistent with models of geographical parthenogenesis.
authors.affiliation: Department of Entomology, National Taiwan University, Taipei, Taiwan 10617, ROC.
authors.forename: Chia-chen
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Department of Life Science, National Taiwan University, Taipei, Taiwan 10617, ROC; Genome and Systems Biology Degree Program, Institute of Ecology and Evolutionary Biology, and Research Center for Developmental Biology and Regeneration Medicine, National Taiwan University, Taipei, Taiwan 10617, ROC.
authors.forename: Chau-Ti
authors.initials: CT
authors.lastname: Ting
authors.affiliation: Department of Life Science, National Taiwan University, Taipei, Taiwan 10617, ROC.
authors.forename: Ching-Ho
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Biodiversity Research Center, Academia Sinica, Taipei, Taiwan 11529, ROC.
authors.forename: Shu
authors.initials: S
authors.lastname: Fang
authors.affiliation: Department of Entomology, National Taiwan University, Taipei, Taiwan 10617, ROC; Biodiversity Research Center, Academia Sinica, Taipei, Taiwan 11529, ROC.
authors.forename: Hwei-yu
authors.initials: HY
authors.lastname: Chang
mesh_terms: D000818:Animals; D004171:Diploidy; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D019143:Evolution, Molecular; D005260:Female; D005298:Fertility / Q000235:genetics; D056084:Genetic Fitness; D014644:Genetic Variation; D005838:Genotype; D008297:Male; D010312:Parthenogenesis / Q000235:genetics*; D010641:Phenotype; D012098:Reproduction / Q000235:genetics; D012726:Sexual Behavior, Animal; D013045:Species Specificity