Biology subjects

De Nardo, A. N.

Publications and source records attributed to De Nardo, A. N..

3 recordsLinked to original sources

bioRxiv2025

Male gut microbiome mediates post-mating sexual selection in Drosophila

When females mate with multiple males, sexual selection continues after mating and favors males with more competitive ejaculates. While these traits are physiologically costly and sensitive to internal state, the effects of the gut microbiome on male reproductive performance remains underexplored. Here, we tested how gut microbial communities influence sperm competition outcomes and the traits underpinning them by inoculating male Drosophila melanogaster with fully factorial synthetic consortia of five common commensal bacteria. We found highly context-dependent and non-additive microbial effects, along with two general patterns: Acetobacter-dominated microbiomes enhanced sperm transfer and increased paternity shares by 20-27% relative to germ-free males, whereas species richness strongly predicted sperm viability and female sperm storage. These results indicate that gut microbes contribute to multiple components of ejaculate performance through distinct pathways, potentially including nutrient provisioning for spermatogenesis, acetate-mediated energy metabolism, and microbe-dependent modulation of female sperm use. By integrating microbial ecology with reproductive biology, our findings establish the gut microbiome as an overlooked but fundamental modulator of sexually selected traits. This perspective helps clarify how non-genetic and community-based factors generate phenotypic variation under strong selection and provides a framework for future work on the mechanisms, transmission routes, and evolutionary consequences of host-microbe interactions in reproduction.

evolutionary biology↗

bioRxiv2025

Microbiome-mediated resilience and cross-generational consequences in male Drosophila exposed to combined environmental stressors

Environmental stressors like heat extremes and pesticide exposure can significantly threaten insect reproduction, yet the interplay of these stressors and the potential mitigating role of the gut microbiome remain poorly understood, particularly across generations. This study investigated the interactive effects of acute heat stress and sublethal imidacloprid exposure on male Drosophila melanogaster reproductive success and the subsequent fitness of their offspring. We manipulated the gut microbiome of male flies (germ-free or colonized with one or five bacterial species) and subjected them to individual or combined stress. Our findings reveal that combined stress synergistically impairs male fitness traits, an effect partially buffered by higher microbiome diversity. We further demonstrate cross-generational consequences, with paternal stress exposure also impacting offspring fitness. Our results highlight the crucial role of the gut microbiome in mediating resilience to environmental stress and underscore the importance of considering multi-stressor and intergenerational effects in ecological risk assessments.

ecology↗

bioRxiv2024

Socio-ecological context modulates significance of territorial contest competition in Drosophila prolongata

The intensity and direction of sexual selection is intricately linked to the social and ecological context. Both operational sex ratios (OSRs) and population densities can affect the ability of males to monopolize resources and mates, and thus the form and intensity of sexual selection on them. Here, we studied how the mating system of the promiscuous and strongly sexually dimorphic fruit fly Drosophila prolongata responds to changes in the OSR and population density. We recorded groups of flies over five days and quantified territory occupancy, mating success, and competitive fertilization success. Although sexual selection was stronger under male-biased than even OSRs but unrelated to density, realized selection on morphological traits was higher under even OSRs and increased with density. Larger and more territorial males achieved both higher mating success and competitive fertilization success, but only under even OSRs. Our combined results also support a shift in the mating system from territorial contest competition to scramble competition under male-biased OSRs and potentially at low density, where there was no clear contribution of the measured traits to reproductive success. Our study emphasizes the limitations of traditional selection metrics and the role of the socio-ecological context in predicting adaptation to a changing environment. SignificanceMating systems are complex and dynamic, adapting to ongoing ecological change. Studies often assume that changes in the socio-ecological context alter the intensity of sexual selection on traits indicating individual fitness, but our work on Drosophila prolongata challenges this view. By manipulating operational sex ratio and population density, and jointly investigating territorial behavior and both pre- and post-mating reproductive success over several days, we reveal the plastic mating strategies in this fly. This dynamism underscores the limitations of static classifications and the importance of studying selection across diverse socio-ecological contexts. This broader perspective advances our understanding of the tight connections between environmental change, population demographics, and the evolutionary process.

evolutionary biology↗