Polygenic sex determination, although suspected in several species, is thought to be evolutionarily unstable and has been proven in very few cases. In the European sea bass, temperature is known to influence the sex ratio. We set up a factorial mating, producing 5.893 individuals from 253 full-sib families, all reared in a single batch to avoid any between-families environmental effects. The pr...

BACKGROUND All honey bee species (Apis spp) share the same sex determination mechanism using the complementary sex determination (csd) gene. Only individuals heterogeneous at the csd allele develop into females, and the homozygous develop into diploid males, which do not survive. The honeybees are therefore under selection pressure to generate new csd alleles. Previous studies have shown that t...

The genetic cascades regulating sex determination of the housefly, Musca domestica, and the fruitfly, Drosophila melanogaster, appear strikingly different. The bifunctional switch gene doublesex, however, is present at the bottom of the regulatory cascades of both species, and so is transformer-2, one of the genetic elements required for the sex-specific regulation of doublesex. The upstream re...

Two primary dichotomies within vertebrate life histories involve reproductive mode (oviparity versus viviparity) and sex determination (genotypic sex determination versus environmental sex determination). Although reptiles show multiple evolutionary transitions in both parameters, the co-occurrence of viviparity and environmental-dependent sex determination have heretofore been regarded as inco...

background: free fetal dna (ffd) in maternal plasma/serum has increasingly become the source of fetal material for diagnostic purposes in recent years. this source of fetal material can be used for sex determination. rh typing paternally inherited sequences and compound heterozygosity. reports on the lack of consistent pcr amplification of y-chromosome sequences of ffd in maternal plasma/serum ...

BACKGROUND The aim of the study was to investigate if expecting parents wanted to know the sex of the fetus during ultrasound examination and if they had discussed it with the midwife. Another aim was to explore any interest in sex selection. METHODS A longitudinal survey in early and late pregnancy among 2393 women in Sweden. RESULTS Almost all (95.8%, n = 2289) women had discussed sex det...

In 2008 researchers Daniel Warner and Richard Shine tested the Charnov-Bull model by conducting experiments on the Jacky dragon, (Amphibolurus muricatus) [5] in Australia. Their results showed that temperature-dependent sex determination [6] (TSD) evolved in this species as an adaptation to fluctuating environmental temperatures. The Charnov-Bull model, proposed by Eric Charnov and James Bull i...

T he extraordinary diversity of sexdetermination mechanisms has long been noted. Many species resort to environmental cues for the determination of sex. A well known example is temperature-dependent sex determination in many (although not all) reptiles. Yet, many other species use genetic mechanisms, i.e., sex chromosomes, for the determination of sex. The beststudied systems of genetic sex det...

Organisms have evolved a bewildering diversity of mechanisms to generate the two sexes. The honeybee (Apis mellifera) employs an interesting system in which sex is determined by heterozygosity at a single locus (the Sex Determination Locus) harbouring the complementary sex determiner (csd) gene. Bees heterozygous at Sex Determination Locus are females, whereas bees homozygous or hemizygous are ...