How common is balancing selection, and what fraction of phenotypic variance is attributable to balanced polymorphisms? Despite decades of research, answers to these questions remain elusive. Moreover, there is no clear theoretical prediction about the frequency with which balancing selection is expected to arise within a population. Here, we use an extension of Fisher's geometric model of adapt...

Sex allocation theory predicts that mothers should adjust their sex-specific reproductive investment in relation to the predicted fitness returns from sons versus daughters. Sex allocation theory has proved to be successful in some invertebrate taxa but data on vertebrates often fail to show the predicted shift in sex ratio or sex-specific resource investment. This is likely to be partly explai...

the objective of the current study was to examine the extent of variation of genetic improvement in dam of dams genetic pathway after insemination of heifers with sex sorted semen. for this purpose three different sexed semen based strategies were examined including 1: continuous use of sex sorted semen (strategy cs), 2: use of sex sorted semen for the first and the second inseminations and use...

The heterogametic sex chromosomes (i.e. mammalian Y and avian W) do not usually recombine with the homogametic sex chromosomes which is known to lead into rapid degeneration of Y and W due to accumulation of deleterious mutations. On the other hand, some 96% of amphibian species have homomorphic, i.e. non-degenerate Y chromosomes. Nicolas Perrin's fountain-of-youth hypothesis states that this i...

Variation among the leaves, flowers or fruit produced by a plant is often regarded as a nuisance to the experimenter and an impediment to selection. Here, we suggest that within-plant variation can drive selection on other plant-level traits. We examine within-plant variation in floral sex allocation and in fruit set and predict that such variation generates variation in male success among plan...

This study was designed to assess sex-related differences in the selection of an appropriate strategy when facing novelty. A simple visuo-spatial task was used to investigate exploratory behavior as a specific response to novelty. The exploration task was followed by a visual discrimination task, and the responses were analyzed using signal detection

This paper argues that the HFEA’s recent report on sex selection abdicates itsresponsibility to give its own authentic advice on the matters within its remit, that itaccepts arguments and conclusions that are implausible on the face of it and wherethey depend on empirical claims, produces no empirical evidence whatsoever, butrelies on reckless speculation as to what the ‘‘facts’...

Conventional sex roles imply caring females and competitive males. The evolution of sex role divergence is widely attributed to anisogamy initiating a self-reinforcing process. The initial asymmetry in pre-mating parental investment (eggs vs. sperm) is assumed to promote even greater divergence in post-mating parental investment (parental care). But do we really understand the process? Trivers ...

We consider a society where parents prefer boys to girls, but also value grandchildren. Parental sex selection results in a biased sex ratio that is socially ine¢ cient, due to a congestion externality in the marriage market. Improvements in selection techniques aggravate the ine¢ ciency. These results are robust to allowing prices in the marriage market, if the market is subject to frictions. ...

Traditionally, reproductive autonomy meant simply the freedom (assuming it was a real freedom) to decide whether to try and reproduce, with whom, when and where. However, now the issues include the questions of whether reproductive autonomy should extend to include, for example, social sex selection, buying and selling eggs, sperm and embryos, the selection of the characteristics of possible fu...