Biology subjects

Devigili, A.

Publications and source records attributed to Devigili, A..

5 recordsLinked to original sources

bioRxiv2026

Socially-mediated compensatory growth carries hidden sperm costs in male guppies

Phenotypic plasticity allows organisms to mitigate early-life adversity through compensatory growth, yet the long-term costs of such "catch-up" trajectories remain poorly understood, particularly when driven by social factors. While most research focuses on nutritionally induced compensation, we investigate how early social competition--independent of resource availability--shapes adult life-history trade-offs in the guppy (Poecilia reticulata). Our results show that scramble competition among peers during early development triggers compensatory growth once social constraints are removed. Crucially, we reveal a hidden reproductive cost: males exhibiting higher compensatory growth reach a similar adult size but produce significantly fewer sperm at maturity. This deficit persists even when controlling for adult body size, indicating a direct trade-off between somatic recovery and ejaculate investment. Furthermore, we find a negative association between gonopodium length and sperm count, suggesting competing allocations between pre- and postcopulatory traits during growth. These findings reveal a cryptic cost of compensatory growth, where adult morphology conceals underlying differences in reproductive quality. By demonstrating that social environments alone can recalibrate life-history trajectories, we highlight the "ghosts of competition past" as critical determinants of fitness. Our study underscores the necessity of considering ontogenetic history to fully understand the evolution of sexually selected traits in social vertebrates.

evolutionary biology↗

bioRxiv2026

Female reproductive fluid evolves rapidly to favor conspecific sperm

Avoiding fertilization with genetically incompatible partners, whether too similar or too divergent, is a central challenge for sexually reproducing organisms. Selection can favor mechanisms acting before and after mating, with postmating processes potentially compensating for constraints on premating choice. In the postmating context, female reproductive fluid (FRF) can modulate sperm performance and bias fertilization outcomes, but its contribution to reproductive isolation remains unclear. We tested whether FRF mediates discrimination against heterospecific and related sperm in two naturally hybridizing sister species of swordtails, Xiphophorus birchmanni and X. malinche, that diverge in premating behavior towards heterospecifics. Effects of FRF differed sharply between species. In X. malinche, FRF enhanced the velocity of conspecific sperm relative to heterospecifics, consistent with postmating discrimination against hybridization. In contrast, FRF in X. birchmanni did not favor conspecific sperm. Evidence for inbreeding avoidance was weaker, and we found no indication of a trade-off between discrimination against genetically similar and dissimilar sperm. These results show that female reproductive fluid can serve as a rapidly evolving axis of reproductive isolation through postmating female choice.

evolutionary biology↗

bioRxiv2025

From microbiome to sperm motility traits: An inside out perspective

Growing interest in the relationship between microbiome composition and host biology has revealed the many ways host-associated microbes influence physiology, ecology, and evolution. However, microbial communities associated with reproductive organs - and their roles in reproduction - remain poorly understood. Here, we characterized the skin- and ejaculate-associated microbiomes in an internally fertilizing fish and tested whether microbial diversity and specific bacterial taxa correlate with sperm motility traits key for reproductive success. We used the guppy (Poecilia reticulata), a well-established model in ecology and evolutionary biology with well-characterised reproductive physiology. In guppies, sperm velocity is a validated predictor of male reproductive performance, making them a powerful system for exploring microbiome-fertility interactions. Our analyses reveal a correlation between skin microbiome diversity and sperm performance. Notably, increased skin microbiome total richness is associated with reduced sperm velocity, whereas no significant associations were detected for ejaculate-associated microbiomes. We also identified bacterial taxa across both tissues that were positively or negatively linked with sperm performance. These findings suggest that, while the ejaculate-associated microbiome may directly influence sperm traits, the skin microbiome could serve as a proxy for reproductive potential by reflecting systemic physiological and immunological states associated with fertility.

microbiology↗

bioRxiv2025

Habitat complexity alters the strength of sexual selection on brain size in a livebearing fish

Animals often reproduce in complex environments, which should generate selection for both enhanced detectability in signaling traits and improved cognitive processing abilities. However, the extent to which signaling and cognitive traits have evolved to overcome the challenges of interacting in complex habitats remains understudied. We examined whether habitat complexity influences sexual selection in the pygmy halfbeak, Dermogenys collettei, a small livebearing freshwater fish. Using free-swimming arenas, we created low- and high-complexity environments and observed mating behaviors in mixed-sex groups. While the opportunity for sexual selection did not differ significantly between environments for either sex, we observed positive selection gradients for both male and female brain size in open arenas, but not in complex habitats. Interestingly, no clear selection on male or female ornamentation was detected in either environment. Our findings suggest that habitat complexity may limit selection pressures on cognitive traits, such as brain size, without significantly affecting visual ornamentations role in mating success.

animal behavior and cognition↗

bioRxiv2022

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

Predation risk perception can alter mating behaviours in males and females, but the consequences for sexual selection remain underexplored. We have previously shown that in experimental populations of Trinidadian guppies Poecilia reticulata the opportunity for sexual selection (i.e. the variance in male reproductive fitness) was higher following exposure to a simulated risk of predation than in a no-risk condition. We build upon this result by exploring whether imminent predation risk affects: 1) the relationship between the opportunity for sexual selection and the actual strength of selection on male traits and 2) the traits contributing to male fitness, and he shape of selection on these traits. While predation risk increased the variance in male fitness, realised selection on traits remained unaffected. Pre- and postcopulatory traits follow complex patterns of nonlinear and correlational selection in both treatments. Differences in selection gradients deviate from predictions based on evolutionary responses to predation, the most notable being stronger selection on courtship rate under predation risk. Our results demonstrate that the operation of sexual selection can be altered by perception of an imminent predation risk and reinforce the notion that both trait-based and variance-based metrics should be employed for an informative quantification.

evolutionary biology↗