Biology subjects

Chapman, T.

Publications and source records attributed to Chapman, T..

At least 19 recordsLinked to original sources

bioRxiv2026

Genomic signals of local adaptation in UK black alder populations (Alnus glutinosa)

Black alder (Alnus glutinosa) is a native tree species in the British Isles, which it colonised after the last glaciation from continental refugia. It is now a widespread pioneer species, thriving on wetlands and riverbanks. We present whole genome sequence data for 324 alder seedlings grown from seed collected from 44 populations across the UK. Among these we found two triploids and one sample with trisomy at chromosome five. Removing these, we found little population genetic structure apart from diverging northern populations with lower diversity. Using Latent-Factor Mixed Models (LFMM) analyses we identified 1,364 loci whose allele frequencies were significantly associated with environmental variables. Of these loci, 93% were associated with the number of snow days. In contrast, the greatest total genomic signal (variance in SNP effect sizes of 7.38 million SNP loci) was observed for mean temperature of the wettest quarter and annual number of frost days. Estimates of maladaptation using 1.49 million SNPs, predicted that northern populations are worst adapted to present and future worst-case climates. Our results suggest that similarity of source-site temperature variables should be prioritised when choosing seed sources for new planting, and northern populations could benefit from assisted gene flow from the south.

plant biology↗

bioRxiv2026

Woodland age, ancient trees, and population size as proxies of genetic diversity

Climatic and biogeographic variables are often used as a proxy for tree genetic diversity, but local factors can also influence it. We propose that woodland age, presence of ancient trees, and population size could impact genetic diversity. Using the RBG Kew UK National Tree Seed Project as a study case, we examined how these factors are accounted for during seed collection. We found 42% of tree seed collections come from ancient woodlands and that 8.4% overlap with ancient trees. Sampled forest patches size ranges from few individuals to several thousand. We then carried out a pilot to examine the role of population size on functional traits variation, testing the relationship between population size and seed germination and seedling thermal stress sensitivity in three populations of the Betula pubescens Ehrh. complex. We found that seeds and seedlings from larger populations showed higher fitness and stress resistance. Our results highlight the importance of local factors to predict variation in functional traits, relevant for tree resilience. Existing seed collections of native species stored in conservation seed banks offer a valuable resource to explore these factors and improve our understanding of genetic diversity in tree populations, with implications for biodiversity conservation and forestry production.

plant biology↗

bioRxiv2026

A novel polymerase III promoter for gene editing in the agricultural pest Ceratitis capitata

We report the identification and functional validation of a 7SK RNA polymerase III promoter in the Mediterranean fruit fly, Ceratitis capitata. CRISPR/Cas9-based genetic control strategies for this global agricultural pest, including gene drives and precision guided sterile insect approaches, require efficient guide RNA expression, yet only a single U6 Pol III promoter had previously been validated for this purpose in C. capitata, and no 7SK promoter had been characterised in any Tephritid species. Using comparative genomics with Drosophila orthologues, we identified a previously unannotated 7SK gene in the C. capitata genome, confirmed its transcriptional activity by RT-PCR, and demonstrated that the cloned promoter drives functional guide RNA expression in CRISPR/Cas9-mediated knockouts of the white gene. Comparative analysis identified putative 7SK orthologues across the Tephritid fruit flies. The availability of this additional new Pol III promoter will enable multiplexed guide RNA strategies using distinct promoters, supporting more robust genetic control designs. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/719894v2_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1ba5271org.highwire.dtl.DTLVardef@17aba3aorg.highwire.dtl.DTLVardef@584702org.highwire.dtl.DTLVardef@19dd47b_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2026

Sexual selection purges mutation load, but not overall genetic diversity in populations, decreasing vulnerability to extinction

Theory suggests sexual selection will enhance population viability by purging deleterious alleles. However, direct genomic evidence for this fundamental idea is scarce and contradictory. We combined long-term experimental evolution with whole-genome re-sequencing to directly test how sexual selection affects mutation load, genomic divergence and extinction risk in Tribolium castaneum. After 156 generations, populations evolving under strong sexual selection carried substantially fewer deleterious alleles than populations under weak sexual selection, based on both individual-level estimates of missense and nonsense variants and population-level Rxy analyses, indicating more efficient purging of deleterious alleles. In contrast, nucleotide diversity and runs of homozygosity were similar across treatments, indicating that purging was targeted at deleterious variation, and that reduced mutation load in populations under strong sexual selection was not explained by demographic effects. Importantly, population-level mutation load estimates provided best explained extinction risk under inbreeding, directly linking sexual selection to purging and population viability for the first time. Genome scans of high and low sexual selection populations revealed peaks of divergence, enriched for genes involved in courtship, sex discrimination, and seminal fluid proteins. Our results provide direct genomic evidence that sexual selection can reduce mutation load without eroding standing genetic diversity and thus adaptive potential, while driving adaptive divergence in reproductive traits. This beneficial purging may help explain the widespread prevalence of sexual reproduction in nature despite inherent costs and have important ramifications as to how we manage populations of conservation concern. Significance StatementA long standing and unconfirmed prediction is that sexual selection can improve population health by biasing reproduction away from individuals with high deleterious mutation load. However, direct genomic evidence is lacking, and the indirect data available are scant and contradictory. Now, using whole-genome resequencing of experimental evolved beetle populations, we show that populations evolving under stronger sexual selection carry fewer deleterious mutations and, importantly, are less vulnerable to extinction. Our results provide the first direct genomic support for this long-debated evolutionary process that may help explain the widespread prevalence of sexual reproduction in nature. Our findings also highlight the importance of allowing sexual selection to act in populations of conservation concern.

evolutionary biology↗

bioRxiv2026

Lysine acetylation facilitates competitive recruitment of translation termination factor eRF3a by PABPC1 C-terminal domain

In eukaryotic cells, almost all mRNA transcripts are polyadenylated in the nucleus, with the poly(A)-tail being critical for their export, translation and stability. PABPC1 is a multifunctional RNA-binding protein (RBP) that binds poly(A)-tails and is a key driver of mRNA post-transcriptional regulation. It achieves this in part by interacting with a broad range of PAM2-motif containing proteins that bind the same common site within PABPC1s PABC domain but result in diverse regulatory outcomes. Regulation of this intricate network of interactions remains poorly understood but our previous studies revealed the regulatory potential of mutually-exclusive acetylation or dimethylation of a key lysine sidechain (K606). To address this, we undertook a systematic study of PAM2-motifs, identifying translation termination factor eRF3a and translation repressor PAIP2 as having a >ten-fold higher affinity for PABPC1 relative to eleven other PAM2-motif partner proteins. Acetylation of PABPC1 at K606 specifically enhances its affinity for eRF3a in vitro, and we present the crystal structure of the specifically K606 acetylated C-terminal domain of PABPC1 in complex with the PAM2 motif of eRF3a, providing structural and functional insights into how acetylation facilitates competitive eRF3a recruitment to PABPC1 and mRNA. We further demonstrate that K606 acetylation promotes PABPC1-eRF3a interaction in cells, thereby antagonising other PAM2-dependent RNA effectors. Taken together, our results show that acetylation of lysine 606 in the PABC domain can specifically modulate PABPC1 partner selectivity, providing crucial insight into how PABPC1 multifunctionality can be regulated to coordinate mRNA usage and fate in the cytoplasm.

molecular biology↗

bioRxiv2025

Evolutionary trade-offs between intergenerational and transgenerational fitness effects

Intergenerational and transgenerational fitness effects can shape evolutionary processes. Theoretically, however, intergenerational and transgenerational effects can trade-off with each other with profound consequences for evolutionary processes. Here we show that beneficial intergenerational effects that increase offspring fitness can result in detrimental transgenerational effects that decrease great-grand offspring fitness. We combined theoretical modelling and experimental approaches to investigate multigenerational fitness trade-offs induced by larval starvation in Caenorhabditis elegans. We demonstrate that larval starvation triggers a cascading effect: starved individuals suffered marked fitness losses, their direct offspring enjoyed fitness gains in both starvation and ad libitum environments, but great-grand-offspring paid fitness costs. Demographic simulation models revealed that genotypes exploiting this short-term intergenerational advantage outcompete rival genotypes despite the deferred transgenerational debt. Our findings demonstrate that adaptive intergenerational gains can be intrinsically linked to maladaptive transgenerational outcomes, challenging the assumption that transgenerational effects are inherently beneficial and highlighting the role of multigenerational trade-offs in evolution.

evolutionary biology↗

bioRxiv2025

Enhancing tree seed germination prediction with image-driven machine learning models.

1. Tree planting is crucial for reversing deforestation and meeting net zero targets, requiring a reliable supply of high-quality seeds. Efficient use of limited native seeds can be promoted by sorting methods, but traditional techniques commonly used for agricultural species are often unsuitable for tree seeds due to their high trait variability. 2. Here, we explored the potential of combining image analysis with machine learning models to improve tree seed sorting outcomes. We selected five UK native tree species of interest for tree production and afforestation projects and applied machine learning XGBoost and Convolutional Neural Networks algorithms to predict seed germination using colour and X-ray images as well as features extracted from these images. 3. The machine learning models achieved good accuracy and F1-scores, but their specificity was limited, particularly when relying solely on colour images or related features. This poses a problem, as wild seeds are often scarce, and falsely classifying seeds that germinate as non-germinable would result in a waste of valuable resources. X-ray images and features were highly effective in identifying empty seeds but did not perform well when differentiating filled seeds into germinable and non-viable. Consequently, the models performed best for species with a high proportion of empty seeds. 4. For three of the five species, model performance varied significantly by mother tree, with some trees showing markedly poorer results. This aspect had not been previously investigated and raises concerns that biased seed sorting will disadvantage certain mother trees, leading to the loss of valuable genetic diversity and woodland resilience. Synthesis and applications: The performance of image-based machine learning models in predicting seed germination ultimately depended on whether most non-germinated seeds were empty, non-viable, or dormant. X-ray models showed strong performance in detecting empty seeds, but colour image models exhibited poor results due to the high variability in seed external features, the subtle differences between germinated and non-germinated seeds, and the variability among individual mother trees. Developing open, accessible training databases and more adaptable models is crucial for addressing these limitations and enable technologies to further support large-scale tree production.

plant biology↗

bioRxiv2024

Female fruit flies use social cues to make egg clustering decisions

BackgroundThe ability to respond plastically to environmental variation is a key determinant of fitness. Females may use cues to strategically place their eggs, for example adjusting the number or location of eggs according to whether other females are present, driving the dynamics of local competition or cooperation. The expression of plasticity in egg laying patterns within individual patches, i.e., in contact clusters or not, represents an additional, under-researched and potentially important opportunity for fitness gains. Clustered eggs might benefit from increased protection or defence, and clustering could facilitate cooperative feeding. However, increased clustering is also expected to increase the risk of over-exploitation through direct competition. These potential benefits and costs likely covary with the number of individuals present, hence egg clustering behaviour within resource patches should be socially responsive. We investigate this new topic using the fruit fly Drosophila melanogaster. ResultsOur mathematical model, parameterised by data, verified that females cluster their eggs non-randomly, and increase clustering as group size increases. We also showed that, as the density of adult females increased, females laid more eggs, laid them faster, and laid more eggs in clusters. Females also preferred to place eggs within existing clusters. Most egg clusters were of mixed maternity. ConclusionsCollectively, the results reveal that females actively express plasticity in egg clustering according to social environment cues and prefer to lay in clusters of mixed maternity, despite the potential for increased competition. These findings are consistent with egg clustering plasticity being selected due to public goods-related benefits.

animal behavior and cognition↗

bioRxiv2024

Female oviposition decisions are influenced by the microbial environment

In ovipositing animals, egg placement decisions can be key determinants of offspring survival. One oviposition strategy reported across taxa is egg clustering, whereby a female lays multiple eggs next to one another or next to the eggs of other females. The fitness benefits of egg clustering, especially in mixed maternity clusters, are unknown. In some species, mothers provision eggs with diffusible defence compounds, such as antimicrobials, raising the possibility of public good benefits arising from egg clustering. Here we report that Drosophila melanogaster females frequently lay eggs in mixed maternity clusters. We tested two hypotheses for potential drivers of this oviposition behaviour: (i) the microbial environment affects fecundity and egg placement in groups of D. melanogaster females; (ii) D. melanogaster eggs exhibit antimicrobial activity. The results partially supported the first hypothesis. Females exposed to environmental microbes that naturally colonised the oviposition substrates in the absence of antimicrobial preservatives reduced their levels of fecundity but did not significantly alter egg clustering. In contrast, the presence of commensal (fly-associated) microbes did not affect oviposition. The second hypothesis was not supported. There was no evidence of antimicrobial activity, either in whole eggs or in soluble surface material extracted from them. In conclusion, while there was no evidence that oviposition decisions are shaped by the opportunity to share antimicrobials, there is evidence that the microbial environment provides cues that females use to make sophisticated decisions on fecundity and egg placement.

evolutionary biology↗

bioRxiv2023

Socially plastic responses in females are robust to evolutionary manipulations of adult sex ratio and adult nutrition

BackgroundSocially plastic behaviours are widespread among animals and can have a significant impact on fitness. Here we investigated whether the socially plastic responses of female Drosophila melanogaster can evolve in predictable ways following long term manipulation of adult sex ratio and adult nutrient availability. Previous reports show that female D. melanogaster respond plastically to their immediate same-sex social environment by altering their fecundity, laying fewer eggs after they mate if previously exposed to other females, Fecundity is also highly sensitive to a females immediate nutritional status, being significantly reduced when dietary protein in particular is scarce. On this basis, we predicted that an evolutionary history of exposure to variation in adult sex ratio and adult nutritional environment would select strongly upon a females plastic fecundity responses. ResultsWe used females that had been drawn from replicated lines that had experienced an evolutionary history of male biased, female biased or equal adult sex ratios and either standard or low-quality adult nutrition. We tested the specific predictions that a history of elevated competition among females (in female-biased regimes) would select for increasingly sensitive plastic fecundity responses to the presence of conspecifics, and that these would be magnified under poor nutritional resource regimes. In contrast to the expectations, we found that the plastic responses in females were strikingly robust to perturbations of both sexual competition and nutrient availability and did not differ significantly across any of the evolutionary regimes. The lack of response is not explained by an insufficient strength of selection. For example, among females held in isolation prior to mating, we did observe significant evolutionary responses in virgin egg according to nutritional regime and in virgin egg retention to sex ratio regime. ConclusionThe lack of variation in the existence and magnitude of predicted plasticity is consistent with the idea that the costs of maintaining fecundity plasticity in females are low, benefits high, and that plasticity itself can be hard wired.

evolutionary biology↗

bioRxiv2023

Nutritional insensitivity to mating in male fruit flies

Animals can adjust their consumption of different nutrients to adaptively match their current or expected physiological state. Changes in diet preference can arise from social and sexual experience. For example, in female Drosophila melanogaster fruit flies, a single mating triggers a behavioural switch in diet choice towards increased protein intake and total food consumption, which supports offspring production. In contrast, male diet choice appears to be unaffected by a single mating. However, one mating may not fully capture the impact of mating on male feeding behaviour. Males can often mate multiply in natural settings, and the costs of ejaculate production and energetic courtship may be cumulative, such that males might experience increased nutritional demands only after multiple matings. In this study we tested this idea by measuring the effect of multiple matings on the diet choice of male D. melanogaster fruit flies. Males were assigned to one of three mating treatments - unmated, mated once or mated five times consecutively - and then allowed to feed freely on chemically-defined diets of protein and carbohydrate. In contrast to the prediction, we found that males that mated five times did not alter the amount of food, nor the proportion of protein and carbohydrate consumed, when compared with unmated or once-mated males. This absence of a feeding response occurred despite substantial ejaculate depletion from multiple matings: males sired fewer offspring in each consecutive mating. These results reveal a lack of plasticity in male feeding behaviour according to mating status, despite substantial potential physiological costs, and highlight the remarkably distinct nutritional ecologies of males versus females.

animal behavior and cognition↗

bioRxiv2023

Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: a novel mechanism to promote redox health?

Several rare genetic variations of human XDH have been shown to alter xanthine oxidoreductase (XOR) activity leading to impaired purine catabolism. However, XOR is a multi-functional enzyme that depending upon the environmental conditions also expresses oxidase activity leading to both O {middle dot}- and H O and nitrite ({middle dot}NO -) reductase activity leading to NO. Since these products express important, and often diametrically opposite, biological activity consideration of the impact of XOR mutations in the context of each aspect of the biochemical activity of the enzyme is needed to determine the potential full impact of these variants. Herein, we show that known naturally occurring hXDH mutations do not have a uniform impact upon the biochemical activity of the enzyme in terms of uric acid (UA), reactive oxygen species (ROS) and nitric oxide ({middle dot}NO) formation. We show that the His1221Arg mutant, in the presence of xanthine, increases UA, O2{middle dot}- and NO generation compared to the WT, whilst the Ile703Val increases UA and {middle dot}NO formation, but not O2{middle dot}-. We speculate that this change in the balance of activity of the enzyme is likely to endow those carrying these mutations with a harmful or protective influence over health that may explain the current equipoise underlying the perceived importance of XDH mutations. We also suggest that targeting enzyme activity to enhance the NO2--reductase profile in those carrying such mutations may provide novel therapeutic options, particularly in cardiovascular disease. HighlightsO_LIMutations of xanthine oxidoreductase modulate both its expression and activity C_LIO_LIThe His1221Arg natural mutation increases xanthine oxidoreductase activity C_LIO_LIRaised xanthine oxidoreductase activity coupled with increased availability of nitrite substrate leads to increased NO provision C_LI

biochemistry↗

bioRxiv2023

Developmental diet alters the fecundity-longevity relationship and age-related gene expression in Drosophila melanogaster

The standard evolutionary theory of ageing predicts a negative relationship (trade-off) between fecundity and longevity. However, this relationship can become positive: (i) under the influence of longevity-enhancing mutations; (ii) when individuals have unequal resources; and (iii) in eusocial insects, in which reproductive queens outlive less- or non-reproductive workers. Developmental diet is likely to be central to determining trade-offs as it affects key fitness traits such as adult body size, but its exact role remains uncertain. For example, in Drosophila melanogaster fruit flies, changes in adult diet can affect fecundity, longevity, and gene expression throughout life, but it is unknown how changes in developmental (larval) diet affect fecundity-longevity relationships or gene expression in adults. Using D. melanogaster, we therefore tested the hypothesis that variation in developmental diet alters the directionality of fecundity-longevity relationships in adults, and characterised associated gene expression changes. We reared D. melanogaster larvae on low (20%), medium (100%), and high (120%) SYA (Sugar Yeast Agar) diets, and transferred adult females developing from these larvae to a common (110% SYA) adult diet. We measured life-time fertility (realised fecundity) and longevity of individual adult females and, using mRNA-seq, profiled gene expression changes across two time-points. Adult females raised on the different larval diets exhibited fecundity-longevity relationships that were significantly different in directionality, i.e., varied from positive to negative, despite minimal differences in mean life-time fertility or longevity. Treatments also differed in age-related gene expression, including expression of genes known to be associated with ageing. Hence, this study shows that the sign of fecundity-longevity relationships in adult insects can be altered and even reversed by variation in larval diet quality. Furthermore, larval diet quality may be a key mechanistic factor underpinning positive fecundity-longevity relationships observed in species such as eusocial insects.

evolutionary biology↗

bioRxiv2022

The post-translational modification SUMO affects TDP-43 phase separation, compartmentalization, and aggregation in a zebrafish model

TDP-43 is a nuclear RNA-binding protein that can undergo liquid-liquid phase separation (LLPS) and forms pathological insoluble aggregates in frontotemporal dementia and amyotrophic lateral sclerosis (ALS). Perturbations of TDP-43 function are linked to mislocalization and neurodegeneration. By studying TDP-43 in vivo, we confirmed for the first time that TDP-43 undergoes LLPS and forms biomolecular condensates in spinal motor neurons (MNs). Importantly, we discovered that interfering with the K136 SUMOylation site of TDP-43 altered its phase separation behavior, reducing cytoplasmic mislocalization and aggregation. Introduction of the ALS-linked mutation G294V did not alter these LLPS characteristics, indicating that posttranslational modifications such as lysine-specific alterations can modulate TDP-43 pathogenesis through regulating phase separation. Altogether, our in vivo characterization of TDP-43 confirms the formation of dynamic nuclear TDP-43 condensates in zebrafish spinal neurons and establishes a critical platform to validate the molecular grammar of phase separation that underpins TDP-43 aggregation in ALS and other proteinopathies.

molecular biology↗

bioRxiv2022

Eusocial insect queens show costs of reproduction and transcriptomic signatures of reduced longevity

Eusocial insect queens have been suggested to be counter-examples to the standard evolutionary theory of ageing through lacking costs of reproduction. Using the bumblebee (Bombus terrestris), we tested this hypothesis experimentally against the alternative that costs of reproduction exist in eusocial insect queens, but are latent, resulting in the positive fecundity-longevity relationship typically found in unmanipulated queens. We experimentally increased queens costs of reproduction by removing their eggs, which causes queens to increase their egg-laying rate. Treatment queens had significantly reduced longevity relative to control queens whose egg-laying rate was not increased. In addition, treatment and control queens differed in age-related gene expression based on mRNA-seq in both their overall expression profiles and the expression of ageing-related genes. Remarkably, this occurred principally with respect to relative age, not chronological age. These results provide the first simultaneously phenotypic and transcriptomic experimental evidence of costs of reproduction in queens of eusocial insects and suggest how the genetic pathways underpinning ageing might become remodelled during eusocial evolution.

evolutionary biology↗

bioRxiv2021

Experimental evolution under varying sex ratio and nutrient availability modulates male mating success in Drosophila melanogaster

Biased population sex ratios can alter optimal male mating strategies, and allocation to reproductive traits depends on nutrient availability. However, there is little information on how nutrition interacts with sex ratio to influence the evolution of pre-copulatory and post-copulatory traits separately. To address this omission, here we test how male mating success and reproductive investment evolve under varying sex ratios and adult diet in Drosophila melanogaster using an experimental evolution approach. We found that sex ratio and nutrient availability interacted to determine male pre-copulatory performance. Males from female-biased populations were slow to mate when they evolved on a protein-restricted diet. On the other hand, we found direct and non-interacting effects of sex ratio and nutrient availability on post-copulatory success, without interactions between them. Males that evolved on a protein-restricted diet were poor at suppressing female remating. Males that evolved under equal sex ratios fathered more offspring and were better at supressing female remating, relative to males from male-biased or female-biased populations. These results support the idea that sex ratios and nutrition interact to determine the evolution of pre-copulatory mating traits, but independently influence the evolution of post-copulatory traits.

evolutionary biology↗

bioRxiv2021

Characterisation of the symbionts in the Mediterranean fruitfly gut

Symbioses between bacteria and their insect hosts can range from very loose associations through to obligate interdependence. While fundamental evolutionary insights have been gained from the in-depth study of obligate mutualisms, there is increasing interest in the evolutionary potential of flexible symbiotic associations between hosts and their gut microbiomes. Understanding relationships between microbes and hosts also offers the potential for exploitation for insect control. Here, we investigate the gut microbiome of a global agricultural pest, the Mediterranean fruitfly (Ceratitis capitata). We used 16S rRNA profiling to compare the gut microbiomes of laboratory and wild strains raised on different diets and from flies collected from various natural plant hosts. The results showed that medfly guts harbour a fairly simple microbiome, primarily determined by the larval diet in both wild and laboratory flies. However, regardless of the laboratory diet or natural plant host on which flies were raised, Klebsiella spp dominated the medfly microbiomes and resisted removal by antibiotic treatment. We sequenced the genome of the dominant putative Klebsiella spp (designated Medkleb) isolated from the gut of the Toliman wild type fruitfly strain. Genome-wide ANI analysis placed Medkleb within the K. oxytoca / michiganensis group. Molecular, sequence and phenotypic analyses supported its identity as K. oxytoca. Medkleb has a genome size (5 825 435 bp) which is 1.6 standard deviations smaller than the mean genome size of free-living Klebsiella spp, and lacks some genes involved in environmental sensing. Moreover, the Medkleb genome contains at least two recently acquired unique genomic islands as well as genes that encode pectinolytic enzymes capable of degrading plant cell walls. This may be advantageous given that the medfly diet includes unripe fruits containing high proportions of pectin. These results suggest that the medfly harbours a commensal gut bacterium that may have developed a mutualistic association with its host and provide nutritional benefits.

evolutionary biology↗

bioRxiv2021

Female fruitflies use gustatory cues to exhibit reproductive plasticity in response to the social environment

Animals can exhibit remarkable reproductive plasticity in response to their social surroundings, with profound fitness consequences. The study of such plasticity in females, particularly in same-sex interactions, has been severely neglected. Here we measured the impact of variation in the pre-mating social environment on reproductive success in females and tested the underlying mechanisms involved. We used the Drosophila melanogaster model system to test the effect of varying female group size prior to mating and deployed physical and genetic methods to manipulate the perception of different social cues and sensory pathways. We found that socially isolated females were significantly more likely to retain unfertilised eggs before mating, but to show the opposite pattern and lay significantly more fertilised eggs in the 24h after mating, in comparison to grouped females. More than 48h of exposure to other females was necessary for this socially-induced plasticity to be expressed. Neither olfactory nor visual cues were involved in mediating these responses. Instead, we found that females detected other females through direct contact with the deposits they leave behind, even in the absence of eggs. The results demonstrate that females show striking reproductive plasticity in response to their social surroundings and that the nature of their plastic reproductive responses, and the cues they use, differ markedly from those of males. The results emphasise the stark contrasts in how each sex realises reproductive success.

evolutionary biology↗