Absence of reproduction-immunity trade-off in male Drosophila melanogaster evolving under differential sexual selection

Abstract

Background: The theory of trade-off suggests that limited resources should lead to trade-off in resource intensive traits such as, immunity related and sexually selected traits in males. Alternatively, sexual exaggerations can also act as an honest indicator of underlying immunocompetence, leading to positive correlations between these traits. Evidences in support of either hypothesis in invertebrates are equivocal. Whereas several studies have addressed this question, few have used naturally occurring pathogens and realized post infection realized immunity (e.g., survivorship) to assay the fitness correlations between these two sets of traits. Results: Adopting an experimental evolution approach, we evolved replicate populations of Drosophila melanogaster under high and low sexual selection regimes for over a hundred generations and found the following in virgin and mated males in three separate assays: a. Post infection survivorship against two natural pathogens-Pseudomonas entomophila (Pe) and Staphylococcus succinus (Ss): Mated males survived better against Pe, but were no different than virgins against Ss. b. Bacterial clearance ability against a third natural pathogen Providencia rettgeri (Pr): Mated males had significantly lower CFUs than virgins. However, sexual selection history had no effect on realized immunity of either virgin or mated males. Conclusion: We show that while mating can affect realized immunity in a pathogen specific way, sexual selection did not affect the same. The results highlight that complex polygenic traits such as immunity and reproductive traits not necessarily evolve following a binary trade-off model. We also stress the importance natural pathogens while studying sexual selection-immunity correlations.

Sex, age, and parental harmonic convergence behavior affect the immune performance of Aedes aegypti offspring

“…In males, progeny from parents that harmonically converged demonstrated lower melanization rates than those from parents that did not converge. One potential explanation for this is that male offspring with fathers that successfully converged may allocate resources across energetically competing life history demands (like mating and mounting an immune response 61 – 63 ) differently than males produced by fathers that did not successfully converge. Upon emergence, the fitness of a male mosquito will be dependent upon his ability to compete for access to female mosquitoes in a mating swarm and the number of females he successfully mates with.…”

Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity

“…These costs have most often been observed as reductions in fecundity, effectively translating into reproduction-survival trade-offs in the presence of pathogens [ 9 , 10 , 12 , 22 , 30 – 34 ]. In polygamous species, where sexual selection on males is intense, females are often predicted to gain more than males from investing in survival and longevity at the cost of current reproduction and mating effort [ 3 , 9 , 35 ] and are therefore also predicted to invest more in immunity than males (but see: [ 2 , 10 , 24 , 35 – 37 ]). Sexual selection may also have pronounced direct effects on optimal investment in immunity, as it may dictate the economics of reproduction [ 23 , 27 , 38 , 39 ] and lead to elevated mating rates [ 40 ], which in turn may increase disease transmission [ 16 , 24 , 25 , 28 ].…”

“…It has, for example, been suggested that tissue-specific (i.e. in the reproductive tract) immune responses upon mating can lead to allocation trade-offs with systemic immunity [ 44 , 52 ], but few studies have provided direct experimental evidence for a causal link between the mating system and the evolution of sex-specific immunity trade-offs [ 2 , 37 , 49 , 50 , 53 ]. To fill this empirical void, we assessed how variation in the intensity of sexual conflict and mating rates in the seed beetle Callosobruchus maculatus affects (i) the evolution of male and female phenoloxidase (from hereon: PO) activity, a major component of invertebrate immunity involved in wound healing and encapsulation of pathogens [ 54 , 55 ], and (ii) associated immunopathological consequences of bacterial infections unrelated to mating.…”

Distinct inflammatory and transcriptomic profiles in dominant versus subordinate males in mouse social hierarchies

“…One of the immune processes involving IL-1B signaling is the activation of inflammasomes. However, we did not find significant transcription level differences in any of the genes involved in IL-1B processing and NLRP3 inflammasome activation, such as Il18, Nlrp3, Asc, Aim2, and Casp1 (Guo et al, 2015;Syed et al, 2020). This suggests potential statusdependent health outcomes in liver are mediated by other downstream IL-1B signaling pathways.…”