Biology subjects

Vega-Trejo, R.

Publications and source records attributed to Vega-Trejo, R..

5 recordsLinked to original sources

bioRxiv2025

Sperm storage reduces sperm and embryo quality in animals

In many animals, sperm are stored for extended periods either in the reproductive tracts of males before ejaculation, or of females after copulation. Sperm storage reduces the risk of sperm limitation in both sexes and avoids the costs of female re-mating. However, sperm storage can lead to post-meiotic sperm senescence, i.e. within-sperm-age-dependent deterioration, potentially impacting conceived offspring and lowering male and female fitness. Yet, the extent and magnitude of such deterioration and the variables modulating it during sperm storage are not well understood. Using a meta-analysis across humans (115 studies) and non-human animals (56 studies from 30 species), we investigate how in-vivo sperm storage affects sperm quality, fertilisation success, and offspring quality. In humans, sperm storage leads to greater sperm oxidative stress and DNA damage, and reduces sperm viability and motility. In other animals, sperm performance and embryo quality decline. We identify the duration of sperm storage, the design used for sampling individuals, and the sex of the individual storing sperm as potentially important moderators of the effects of sperm storage. These findings have key biomedical implications, including optimising the timing of ejaculation and fertilisation in fertility clinics or captive breeding programs. Overall, our results reveal the mechanisms that cause post-meiotic sperm senescence, the fitness consequences of sperm storage, and provide evolutionary insights into sex-specific adaptations that potentially mitigate the detrimental effects of sperm storage.

evolutionary biology↗

bioRxiv2024

No evidence for paternal age effects on sons or daughters, when accounting for paternal sperm storage

O_LIThe age at which a father reproduces is predicted to affect not only his own fertility but also the fitness of his offspring. Specifically, offspring born to old fathers are assumed to be of a lower quality than those conceived by young fathers. However, when fathers have low mating rates, paternal age might be confounded with the duration for which mature sperm are stored in fathers prior to ejaculation. C_LIO_LIStudies that disentangle the confounding effects of paternal sperm storage duration from those of paternal age, on offspring, are lacking. We use Drosophila melanogaster to test the separate and interactive effects of paternal age and sperm storage duration (sexual rest) on the survival and lifetime reproduction of offspring. C_LIO_LIAs expected, old fathers produce fewer offspring than young fathers. But surprisingly, paternal age does not influence the survival or lifetime reproductive success of either sons or daughters. Instead, sons conceived by fathers with long durations of sexual rest have lower reproductive success than sons conceived by fathers with short durations of sexual rest. C_LIO_LIWe further discover that daughters of low reproductive quality selectively disappear with age, but sons do not, highlighting that demographic processes need to be accounted for when studying paternal age effects. C_LIO_LIOverall, our study suggests that paternal age effects might not be as pervasive as previously assumed. We emphasize that a more nuanced understanding of the mechanisms causing paternal age effects is required, so that studies do not misattribute effects of paternal sperm storage to age. C_LI

evolutionary biology↗

bioRxiv2024

Artificial selection for adult predation survival impacts life history and morphology in guppies (Poecilia reticulata)

Predation is accepted as a major evolutionary driver of life history and morphology. However, whether these traits evolve directly via predation or via indirect effects is largely unresolved. We used artificial selection over three generations to experimentally test the impact of adult predation on the evolution of life history and morphology in guppies (Poecilia reticulata). We found that, compared to control fish, predation-selected fish produced larger offspring and larger broods early in life. However, other life history parameters, such as interbrood interval and total number of offspring, showed no response. We also found that predation-selected for smaller and lighter females and for shorter tails and gonopodia in males, with no effect on body colouration. Our results show that while several traits evolve fast under selection on adult predation, several classic predation-dependent traits seem unaffected by predation selection. By comparing our experimental results to those from natural populations we can disentangle the contribution of direct and indirect effects on trait evolution under predation pressure.

evolutionary biology↗

bioRxiv2023

No general effects of advancing male age on ejaculates: a meta-analysis across the animal kingdom

Senescence, the deterioration of organismal function with advancing age, is a puzzling biological phenomenon. While actuarial senescence (i.e., age-dependent increases in mortality rates) is well described across some taxa, reproductive senescence (i.e. age- dependent declines in reproduction) is less understood, especially in males, with mixed patterns reported across studies. To examine the evidence for male reproductive senescence, we investigated how advancing male age affects ejaculate traits across non-human animals via a meta-analysis yielding 1814 effect sizes from 379 studies. We found no evidence for a general pattern of reproductive senescence. Instead, we found high heterogeneity for how reproduction changes with male age across animals. Some of this heterogeneity (>10%) was associated with biological factors. For example, there were taxonomical differences for some ejaculate traits -- sperm motility declined with male age in lab rodents and fish, whereas ejaculate size improved with male age in bulls, fish, and insects. Some methodological factors were also important in explaining this heterogeneity: studies sampling a larger proportion of a species lifespan were more likely to detect senescence in ejaculate traits, emphasising the need to examine the full life cycle of species to document senescence. Contrary to predictions, we reveal that the evidence for senescence in ejaculate traits is sporadic. Our findings will help generate novel hypotheses and identify more effective methodological approaches for studying male reproductive senescence.

evolutionary biology↗

bioRxiv2022

Jumping out of trouble: Evidence for a cognitive map in guppies (Poecilia reticulata)

Spatial cognitive abilities allow individuals to remember the location of food patches, predator hide-outs, or shelters. Animals typically incorporate learnt spatial information or use external environmental cues to navigate their surroundings. A spectacular example of how some fishes move is through aerial jumping. For instance, fish that are trapped within isolated pools, cut off from the main body of water during dry periods, may jump over obstacles and direct their jumps to return to safe locations. However, what information such re-orientation behaviour during jumping is based on remains enigmatic. Here we combine a lab and field experiment to test if guppies (Poecilia reticulata) incorporate learnt spatial information and external environmental cues (visual and auditory) to determine where to jump. In a spatial memory assay we found that guppies were more likely to jump towards deeper areas, hence incorporating past spatial information to jump to safety. In a matched vs. mismatched spatial cue experiment in the field, we found that animals only showed directed jumping when visual and auditory cues matched. We show that in unfamiliar entrapments guppies direct their jumps by combining visual and auditory cues, while in familiar entrapments they use a cognitive map. We hence conclude that jumping behaviour is a goal-directed behaviour, guided by different sources of information and involving important spatial cognitive skills.

animal behavior and cognition↗