Exploring OR2H1-Mediated Sperm Chemotaxis: Development and Application of a Novel Microfluidic Device.

Microfluidic platforms have emerged as critical technologies for exploring sperm chemotaxis, providing precise gradient control, and facilitating in-depth behavioral assessment. We designed a novel, user-friendly microfluidic device that is optimized for human sperm morphology and motility. The device was validated using two well-established sperm chemoattractants, progesterone and bourgeonal, demonstrating its reliability and reproducibility.

Stunned by a Heatwave: Experimental Heatwaves Alter Juvenile Responsiveness to the Threat of Predation.

Heatwaves, increasingly prevalent in our rapidly changing climate, significantly impact animals with far-reaching ecological and evolutionary consequences. One of the first responses in animals to stress, including heat stress, is behavioural change, and this can directly influence fitness and survival. Changes in anti-predator behaviour are particularly critical, as they may compromise a prey's ability to evade predators, thus increasing predation risk and jeopardising survival.

Social buffering of oxidative stress and cortisol in an endemic cyprinid fish.

Fish exhibit complex social behaviours that can influence their stress levels and well-being. However, little is known about the link between social interactions and stress in wild fish, especially in running water environments. While many studies have explored the stress axis in fish, most have focused on specific social contexts, leaving gaps in understanding stress responses to social changes.

Female reproductive fluid attracts more and better sperm: implications for within-ejaculate cryptic female choice.

Mounting evidence shows that the female reproductive fluid (FRF) can differently affect sperm performance of different males by biasing paternity share among competing males. Here, we tested for the first time the potential of 'within-ejaculate cryptic female choice' mediated by the FRF in the zebrafish (). Using a recently developed sperm selection chamber, we separated and collected FRF-selected from non-selected sperm to compare the two subpopulations of sperm in terms of sperm number, viability, DNA integrity and fertilizing ability.

Resource-dependent investment in male sexual traits in a viviparous fish.

Exaggerated and conspicuous sexually selected traits are often costly to produce and maintain. Costly traits are expected to show resource-dependent expression, since limited resources prevent animals from investing maximally in multiple traits simultaneously. However, there may be critical periods during an individual's life where the expression of traits is altered if resources are limited.

Immediate predation risk alters the relationship between potential and realised selection on male traits in the Trinidad guppy .

Imminent predation risk affects mating behaviours in prey individuals in a multitude of ways that can theoretically impact the strength of sexual selection, as well as its operation on traits. However, empirical studies of the effects of imminent predation risk on sexual selection dynamics are still scarce. Here we explore how perceived predation affects: (1) the relationship between the opportunity for selection and the actual strength of selection on male traits; and (2) which traits contribute to male fitness and the shape of selection on these traits.

Does brain size affect mate choice? An experimental examination in pygmy halfbeaks.

Choosing a mate is one of the most important decisions in an animal's lifetime. Female mate choice is often guided by the presence or intensity of male sexual ornaments, which must be integrated and compared among potential mates. Individuals with greater cognitive abilities may be better at evaluating and comparing sexual ornaments, even when the difference in ornaments is small.

Sperm Accumulation Induced by the Female Reproductive Fluid: Putative Evidence of Chemoattraction Using a New Tool.

There is considerable evidence that female reproductive fluid (FRF) interacts intimately with sperm, affecting several sperm traits, including sperm motility and longevity, and ultimately fertilization success. One of the first documented interactions between FRF and sperm is the ability of FRF to attract and guide sperm towards the eggs. However, most of the evidence of FRF's chemoattraction proprieties comes from a limited number of taxa, specifically mammals and invertebrate broadcasting spawners.

Corrigendum to: Male-male behavioral interactions drive social-dominance mediated differences in ejaculate traits.

[This corrects the article DOI: 10.1093/beheco/araa118.].

Male-male behavioral interactions drive social-dominance-mediated differences in ejaculate traits.

Higher social status is expected to result in fitness benefits as it secures access to potential mates. In promiscuous species, male reproductive success is also determined by an individual's ability to compete for fertilization after mating by producing high-quality ejaculates. However, the complex relationship between a male's investment in social status and ejaculates remains unclear.

Contrasting female mate preferences for red coloration in a fish.

Understanding how animals select their mates requires knowing the factors that shape mate preferences. Recent theoretical and empirical considerations suggest that female mating status can influence the degree to which a female engages in mate choice, with virgin females predicted to be less choosy than mated females. In this study, we investigated mate choice in both virgin and mated females in the pygmy halfbeak .

Female sperm storage mediates post-copulatory costs and benefits of ejaculate anticipatory plasticity in the guppy.

Males of many species evolved the capability of adjusting their ejaculate phenotype in response to social cues to match the expected mating conditions. When females store sperm for a prolonged time, the expected fitness return of plastic adjustments of ejaculate phenotype may depend on the interval between mating and fertilization. Although prolonged female sperm storage (FSS) increases the opportunity for sperm competition, as a consequence of the longer temporal overlap of ejaculates from several males, it may also create variable selective forces on ejaculate phenotype, for example by exposing trade-offs between sperm velocity and sperm survival.

Chemical signals from eggs facilitate cryptic female choice in humans.

Mate choice can continue after mating via chemical communication between the female reproductive system and sperm. While there is a growing appreciation that females can bias sperm use and paternity by exerting cryptic female choice for preferred males, we know surprisingly little about the mechanisms underlying these post-mating choices. In particular, whether chemical signals released from eggs (chemoattractants) allow females to exert cryptic female choice to favour sperm from specific males remains an open question, particularly in species (including humans) where adults exercise pre-mating mate choice.

Male mate choice for large gravid spots in a livebearing fish.

Male mate choice occurs in a wide range of species, and males can increase their reproductive success by distinguishing between females based on their fecundity (e.g., large body size) or their expected sperm competition risk (e.

Differential gene regulation in selected lines for high and low sperm production in male guppies.

In species where females mate with more than one male during the same reproductive event, males typically increase the number of sperm produced to boost their fertilization share. Sperm is not limitless, however, and theory predicts that their production will come at the cost of other fitness-related traits, such as body growth or immunocompetence, although these evolutionary trade-offs are notoriously difficult to highlight. To this end, we combined artificial selection for sperm production with a transcriptome analysis using Poecilia reticulata, a fish characterized by intense sperm competition in which the number of sperm transferred during mating is the most important predictor of fertilization success, yet sperm production is highly variable among males.

Predation shapes sperm performance surfaces in guppies.

Sperm velocity is a key determinant of competitive fertilization success in many species. Selection is therefore expected to favour the evolution of faster sperm when the level of sperm competition is high. However, several aspects can determine the direction and strength of selection acting on this key performance trait, including ecological factors that influence both sperm competition and the strength of selection acting on correlated traits that may constrain evolutionary responses in sperm velocity.

Sexual selection and ageing: interplay between pre- and post-copulatory traits senescence in the guppy.

Traits associated with mating and fertilization success are expected to senesce with age, but limited information is available on their relative rates of senescence. In polyandrous species, male reproductive fitness depends on both mating and fertilization success. Because successful mating is a prerequisite for post-copulatory sexual selection, ejaculate traits are expected to senesce faster than pre-copulatory traits, as pre-copulatory sexual selection is often deemed to be stronger than post-copulatory sexual selection.

Population demography and heterozygosity-fitness correlations in natural guppy populations: An examination using sexually selected fitness traits.

Heterozygosity-fitness correlations (HFCs) have been examined in a wide diversity of contexts, and the results are often used to infer the role of inbreeding in natural populations. Although population demography, reflected in population-level genetic parameters such as allelic diversity or identity disequilibrium, is expected to play a role in the emergence and detectability of HFCs, direct comparisons of variation in HFCs across many populations of the same species, with different genetic histories, are rare. Here, we examined the relationship between individual microsatellite heterozygosity and a range of sexually selected traits in 660 male guppies from 22 natural populations in Trinidad.

Directional postcopulatory sexual selection is associated with female sperm storage in Trinidadian guppies.

Female sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for nondirectional PCSS should increase. We explored these questions in the guppy (Poecilia reticulata), by allowing females to mate multiply and by comparing the paternity pattern in two successive broods.

Multivariate selection drives concordant patterns of pre- and postcopulatory sexual selection in a livebearing fish.

In many species, females mate with multiple partners, meaning that sexual selection on male traits operates across a spectrum that encompasses the competition for mates (that is, before mating) and fertilizations (after mating). Despite being inextricably linked, pre- and postcopulatory sexual selection are typically studied independently, and we know almost nothing about how sexual selection operates across this divide. Here we bridge this knowledge gap using the livebearing fish Poecilia reticulata.

Pattern of inbreeding depression, condition dependence, and additive genetic variance in Trinidadian guppy ejaculate traits.

In polyandrous species, a male's reproductive success depends on his fertilization capability and traits enhancing competitive fertilization success will be under strong, directional selection. This leads to the prediction that these traits should show stronger condition dependence and larger genetic variance than other traits subject to weaker or stabilizing selection. While empirical evidence of condition dependence in postcopulatory traits is increasing, the comparison between sexually selected and 'control' traits is often based on untested assumption concerning the different strength of selection acting on these traits.

Assessment of left ventricular function by pulse wave analysis in critically ill patients.

Purpose: Left ventricular (LV) performance is often quantified by echocardiography in critically ill patients. Pulse wave analysis (PWA) systems can also monitor cardiac function but in a continuous fashion. We compared echocardiographic and PWA-derived indices of LV function.

Determinants of early inadequate vancomycin concentrations during continuous infusion in septic patients.

Vancomycin is frequently administered to critically ill patients by continuous infusion in order to optimise drug efficacy; however, there are few data available on the efficacy of this strategy in septic patients. In this retrospective analysis, 261 patients treated with continuous infusion of vancomycin in the Department of Intensive Care at Hôpital Erasme (Brussels, Belgium) were evaluated. Creatinine clearance (CL(Cr)) was calculated from 24-h urine collection and normalised to body surface area.