Males of many species invest resources in their offspring. For paternal investment to evolve, it must exhibit heritable variation. Using a standard half-sibling quantitative genetic design, we investigated whether genetic variation in male ejaculate size, a trait that affects female fecundity and copulation duration, are present in the seed beetle Callosobruchus maculatus. Ejaculate size was es...

Sexually selected male ejaculate traits are expected to depend on the resource state of males. Theory predicts that males in good condition will produce larger ejaculates, but that ejaculate composition will depend on the relative production costs of ejaculate components and the risk of sperm competition experienced by low- and high-condition males. Under some conditions, when low condition lea...

The study was performed on 4 609 ejaculates obtained from 32 boars, including 14 purebred and 18 two-breed crosses. The ejaculates were collected manually every 4-5 days. The study involved ejaculates collected from each boar from the first day of its insemination use until the day of semen depletion. Each ejaculate was assessed for the following physical parameters: ejaculate volume, sperm con...

While early models of ejaculate allocation predicted that both relative testes and ejaculate size should increase with sperm competition intensity across species, recent models predict that ejaculate size may actually decrease as testes size and sperm competition intensity increase, owing to the confounding effect of potential male mating rate. A recent study demonstrated that ejaculate volume ...

Several hypotheses have been proposed to explain the evolution of polyandry in species that provide nuptial gifts. When nuptial gifts are in the form of nutritional elements in the ejaculate and ejaculate size is correlated with male body size, females can accrue both direct (nutritional) and indirect (genetic) benefits from multiple mating. We examined remating decisions in females of the seed...

Recent theory and empirical evidence suggest a role for sexual conflict in the evolution of male ejaculates, including ‘nuptial gifts’. According to the sexual conflict hypothesis, the greater the probability of female remating, the stronger the selection on males to induce an elevated reproductive rate in their mates, even if this reduces some components of female fitness, such as survivorship...

KondracKi, S., K. GorSKi, a. WySoKinSKa and i. JoZWiK, 2014. correlation of ejaculate parameters and sperm morphology with the ejaculate volume of Pietrain boars. Bulg. J. Agric. Sci., 20: 703-709 The objective was to analyze the connection between physical ejaculate parameters and sperm morphology and the volume of Pietrain boar ejaculates. The study covered 87 ejaculates collected from 10 Pol...

Ejaculate size in seed beetles (Coleoptera: Bruchidae) is subject to both sexual and fecundity selection. We examined interpopulation variation and inheritance of ejaculate size in the seed beetle Callosobruchus maculatus (F.). There was signiÞcant variation among three populations in both body mass and the proportion of a maleÕs body mass that was transferred to females during mating. The seed...

OBJECTIVES To report our experience with transurethral resection of the ejaculatory ducts (TURED) in infertile men with symptomatic ejaculatory duct obstruction (EDO). PATIENTS AND METHODS Before surgery, all patients complained of a decrease in the volume of their ejaculate, 14 of 15 had a non-projectile ejaculation, nine had a genitourinary infection necessitating antibiotic treatment, and ...

The function of nuptial gifts has generated longstanding debate. Nuptial gifts consumed during ejaculate transfer may allow males to transfer more ejaculate than is optimal for females. However, gifts may simultaneously represent male investment in offspring. Evolutionary loss of nuptial gifts can help elucidate pressures driving their evolution. In most katydids (Orthoptera: Tettigoniidae), ma...