25 26 Although most vertebrates reproduce sexually, a small number of fishes, amphibians, 27 and reptiles are known in which reproduction is asexual i.e. without meiotic 28 recombination. In fishes, these so-called “unisexual” lineages usually comprise only 29 females, and utilize co-occurring males of a related sexual species to reproduce via 30 gynogenesis or hybridogenesis. Here we examine p...

Sperm that are produced by males homozygous for ms(3)K81 , a male sterile mutant of Drosophila melanogaster, are defective in syngamy but are capable of activating eggs to develop gynogenetically. The activated eggs usually produce haploid embryos, but a small fraction (10( -4)-10(-5)) of them give rise to diploid impaternate adults. To know the cytological mechanisms by which these impaternate...

All-female 'species' of fish have been shown to be great models in ecological and evolutionary studies because of the insights they can provide into the origin and evolution of asexuality, the ecology of hybrids, associations between genotype and environment, and the maintenance of sex. Gynogenetic organisms that evolved from sexual ancestors, and combine the disadvantageous traits from sexuali...

The mating system of the sexual–asexual complex of sailfin mollies, Poecilia latipinna, and Amazon mollies, P. formosa, depends on the close proximity of individuals in aggregations or shoals because P. formosa is gynogenetic (that is, sperm only initiate embryogenesis but do not contribute genetic material) and must be inseminated by male P. latipinna. Furthermore, female P. latipinna copy the...

P lant reproduction is characterized by an “alternation of generations”—the dominant diploid sporophyte phase in higher plants is punctuated by short, multicellular haploid phases in male and female gametophytes buried within the flowers. Double fertilization produces two major structures, the diploid embryo, and triploid endosperm, a nutritive tissue for the embryo. Crop breeders rely on recom...

haploid plant per floret (Devaux, 1988). Androgenesis induction in microspores may be affected by various An efficient doubled-haploid production technology that induces factors which cause low induction efficiency and by gehomozygosity can greatly reduce the time and cost of cultivar developnotype dependence (Dunwell, 1985). Most advances toment. Low efficiency of doubled-haploid production pr...