The typical pattern in hymenopteran species is that females are produced from fertilized eggs but that males arise parthenogenetically from unfertilized eggs (arrhenotoky). In some species, however, unfertilized eggs can yield diploid female offspring through the process of thelytokous parthenogenesis. Indeed, it is puzzling why such asexual mutants have not outreproduced their sexual counterpa...

This paper forms the first part of broader research dealing with possibilities for a feminine ????, i.e., starting point or source change, in early Greek thinking. Thus, it involves comparative analyses material provided by Homer, The Homeric hymn to Apollo, Hesiod?s Theogony and Derveni Papyrus, latter text being ?the only one that can, without shadow doubt, be described as ?Orphic?? (Brisson,...

The adult stage of Haemaphysalis leporis-palustris was studied. Two infestations consisted of male and female ticks on two rabbits (Oryctolagus cuniculus). Other two infestations consisted of only female ticks on two O. cuniculus. Females fed without males showed differences in some biological parameters when compared to females fed with males. Parthenogenesis is reported for the first time by ...

Facultative parthenogenesis (FP)-asexual reproduction by bisexual species-has been documented in a variety of multi-cellular organisms but only recently in snakes, varanid lizards, birds and sharks. Unlike the approximately 80 taxa of unisexual reptiles, amphibians and fishes that exist in nature, FP has yet to be documented in the wild. Based on captive documentation, it appears that FP is wid...

Genetically matched pluripotent embryonic stem (ES) cells generated via nuclear transfer or parthenogenesis (pES cells) are a potential source of histocompatible cells and tissues for transplantation. After parthenogenetic activation of murine oocytes and interruption of meiosis I or II, we isolated and genotyped pES cells and characterized those that carried the full complement of major histoc...

The most common way animals reproduce is bisexuality, namely through the mixis of male and female gametes. Bisexual reproduction relies on the Mendelian mechanism, although several additional modes also occur. In turn, the Mendelian inheritance of genetic variability stands on the meiotic process, which entrains recombination and chromosome reshuffling within the frame of a balanced segregation...

Drosophila mercatorum is a sexual species that can reproduce parthenogenetically. Previous studies revealed that parthenogenetic strains had "coadapted genomes" with high fitness under parthenogenesis and total homozygosity due to nonadditive and nonmultiplicative fitness interactions between chromosomal segments scattered throughout the genome. To study the evolutionary origins of such coadapt...

Organisms that reproduce by sperm-dependent parthenogenesis are asexual clones that require sperm of a sexual host to initiate egg production, without the genome of the sperm contributing genetic information to the zygote. Although sperm-dependent parthenogenesis has some of the disadvantages of sex (requiring a mate) without the counterbalancing advantages (mixing of parental genotypes), it ap...

In so-called unisexual teleost fishes, a broad spectrum of evolutionary stages with varying amounts of sexual elements has evolved. These range from pure sperm-dependent parthenogenesis (gynogenesis) without or with different amounts of paternal leakage to hybridogenesis with hemiclonal diploid gametogenesis or genome elimination followed by meiosis (meiotic hybridogenesis). All of these phenom...