Highlights Survey data collected from equine-assisted services programs that offer unmounted (ground) document the need for standardized equine safety evaluations. 36.7% of respondents used an objectively defined method (i.e., a percentage, number, rating scale, or yes/no checklist must be achieved by prior to them entering progr...

Adaptations that enhance fitness in one sex may be harmful to members of the opposite sex and lead to antagonistic coevolution between the sexes. In fruit flies, for example, selection for fertilization success has rendered the male ejaculate slightly toxic to females. Here we investigated whether mating imposes a cost upon female fitness in a polyandrous pierid butterfly (Colias eurytheme ) by...

38 fresh ejaculates were examined, of which 23 were cryopreserved in three diluents differing in concentration of glycerol and examined after thawing. For each ejaculate we established the concentration, motility, speed of sperm, percentage of live sperm and the morphological image of the ejaculate using routine laboratory diagnosis and SQA parameters at the initial value and after a 120-minute...

Sperm competition theory predicts that with increase in sperm competition, males either invest more in reproductive organ(s) and/or improve ejaculate investment. We test this idea using experimental evolution in Drosophila melanogaster. We maintained replicate populations of Drosophila melanogaster under male (M) and female (F) biased sex ratio regimes for more than a hundred generations with t...

In species where females mate with multiple males, the sperm from these males must compete to fertilise available ova. Sexual selection from sperm competition is expected to favor opposing adaptations in males that function either in the avoidance of sperm competition (by guarding females from rival males) or in the engagement in sperm competition (by increased expenditure on the ejaculate). Th...

Postmating, prezygotic phenotypes, especially those that underlie reproductive isolation between closely related species, have been a central focus of evolutionary biologists over the past two decades. Such phenotypes are thought to evolve rapidly and be nearly ubiquitous among sexually reproducing eukaryotes where females mate with multiple partners. Because these phenotypes represent interpla...

BACKGROUND The increasing prevalence of cancer survivors who are infertile due to gonadal failure highlights the importance of fertility preservation prior to gonadotoxic treatments. Adolescent cancer patients may not be mature enough to produce sperm by masturbation, leading to the use of alternative methods for obtaining sperm for cryopreservation. The aim of the current study was to evaluate...

We have reported recently the first birth after intrauterine transfer of embryos obtained by injection of round spermatids into oocytes in cases of unexpected azoospermia. Here we provide a complete documentation of the series of 11 cases in which this novel method of infertility treatment was employed. In four of these cases, elongated spermatids were identified in the ejaculate, and it was de...