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430 results for “Queens”
2D Macro-XRF to reveal redacted sections of French queen Marie-Antoinette secret correspondence with Swedish count Axel von Fersen
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Pollen diet mediates how pesticide exposure impacts brain gene expression in nest-founding bumble bee queens
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Data from: "Worker queens"? Behavioral flexibility, juvenile hormone binding protein and Vitellogenin in queens of the little fire ant Wasmannia auropunctata
<p>Many species of social Hymenoptera demonstrate behavioral flexibility, where older workers that typically forage can revert to younger worker tasks, such as nursing, when these are absent. This flexibility is typical of the sterile worker class, yet rare in queens. In the little fire ant (<i>Wasmannia auropunctata</i>) queens have been reported to perform only egg laying. We examined behavior of queens of <i>W. auropunctata</i> after demographic manipulation. When half of the workers were removed from the colony, queens were observed caring for eggs, larvae and pupae as well as eating outside of the nest, like forager workers. We examined the relationship between these atypical queen behaviors and their juvenile hormone binding protein (JHbp) and vitellogenin (Vg) expression via QRT-PCR method. JHbp and Vg expression decreased when queens were performing worker tasks, resembling the expected expression pattern of typical sterile workers. Flexibility in queen behaviors in the little fire ant may be an important adaptation to changing environments. As a significant invasive species, such adaptation may increase the probability of colony survival during propagation. Our results not only present new insights in behavioral flexibility in social insects, but also increases our understanding of the success of this significant invasive species. </p>
Queen pheromone modulates the expression of epigenetic modifier genes in the brain of honeybee workers
<p>Pheromones are used by many insects to mediate social interactions. In the highly eusocial honeybee (<i>Apis mellifera</i>) queen mandibular pheromone (QMP) is involved in the regulation of the reproductive and other behaviour of workers. The molecular mechanisms by which QMP acts are largely unknown. Here we investigate how genes responsible for epigenetic modifications to DNA, RNA and histones respond to the presence of QMP in the environment. We show that several of these genes are upregulated in the honeybee brain when workers are exposed to artificial QMP. We propose that pheromonal communication systems, such as those used by social insects, evolved to respond to environmental signals by making use of existing epigenomic machineries.</p>
Data from: General and species-specific impacts of a neonicotinoid insecticide on the ovary development and feeding of wild bumblebee queens
Bumblebees are essential pollinators of crops and wild plants, but are in decline across the globe. Neonicotinoid pesticides have been implicated as a potential driver of these declines, but most of our evidence base comes from studies of a single species. There is an urgent need to understand whether such results can be generalized across a range of species. Here, we present results of a laboratory experiment testing the impacts of field-relevant doses (1.87–5.32 ppb) of the neonicotinoid thiamethoxam on spring-caught wild queens of four bumblebee species: Bombus terrestris, B. lucorum, B. pratorum and B. pascuorum. Two weeks of exposure to the higher concentration of thiamethoxam caused a reduction in feeding in two out of four species, suggesting species-specific anti-feedant, repellency or toxicity effects. The higher level of thiamethoxam exposure resulted in a reduction in the average length of terminal oocytes in queens of all four species. In addition to providing the first evidence for general effects of neonicotinoids on ovary development in multiple species of wild bumblebee queens, the discovery of species-specific effects on feeding has significant implications for current practices and policy for pesticide risk assessment and use.
Data from: Queen execution, diploid males, and selection for and against polyandry in the Brazilian stingless bee Scaptotrigona depilis
Female mating frequency varies. Determining the causes of this variation is an active research area. We tested the hypothesis that in stingless bees, Meliponini, single mating is due to the execution of queens that make a matched mating at the CSD (complementary sex determination) locus and have diploid male offspring. We studied the Brazilian species Scaptotrigona depilis. We made up 70 test colonies so that 50% (single matched mating), 25% (double mating), 12.5% (4-mating), or 0% (single non-matched mating) emerging brood were diploid males. Queen execution following diploid male emergence was equal and high in colonies producing 50% (77% executed) and 25% (75%) diploid males, versus equal and low in colonies producing 12.5% (7%) and 0% (0%) diploid males. These results show that queens that mate with two males with similar paternity suffer an increased chance of being executed, which selects against double mating. However, double mating with unequal paternity (e.g., 25:75), which occasionally occurs in S. depilis, is selectively neutral. Single mating and double mating with unequal paternity form one adaptive peak. The results show a second adaptive peak at 4-mating. However, this is inaccessible via gradual evolutionary change in a selective landscape with reduced fitness at double mating.
Data from: Running with the Red Queen: host-parasite coevolution selects for biparental sex
Most organisms reproduce through outcrossing, even though it comes with significant costs. The Red Queen hypothesis proposes that selection from coevolving pathogens facilitates the persistence of outcrossing in spite of these costs. We utilized experimental coevolution to test the Red Queen hypothesis, and found that coevolution with a bacterial pathogen (Serratia marcescens) resulted in significantly more outcrossing in mixed mating experimental populations of the nematode Caenorhabditis elegans. Furthermore, we found that coevolution with the pathogen rapidly drove obligately selfing populations to extinction, while outcrossing populations persisted through reciprocal coevolution. Thus, consistent with the Red Queen hypothesis, coevolving pathogens can select for biparental sex.
Data from: Conserved class of queen pheromones stops social insect workers from reproducing
A major evolutionary transition to eusociality with reproductive division of labor between queens and workers has arisen independently at least 10 times in the ants, bees, and wasps. Pheromones produced by queens are thought to play a key role in regulating this complex social system, but their evolutionary history remains unknown. Here, we identify the first sterility-inducing queen pheromones in a wasp, bumblebee, and desert ant and synthesize existing data on compounds that characterize female fecundity in 64 species of social insects. Our results show that queen pheromones are strikingly conserved across at least three independent origins of eusociality, with wasps, ants, and some bees all appearing to use nonvolatile, saturated hydrocarbons to advertise fecundity and/or suppress worker reproduction. These results suggest that queen pheromones evolved from conserved signals of solitary ancestors.
Data from: Queen presence mediates the relationship between collective behavior and disease susceptibility in ant colonies
The success of social living can be explained, in part, by a group's ability to execute collective behaviors unachievable by solitary individuals. However, groups vary in their ability to execute these complex behaviors, often because they vary in their phenotypic composition. Group membership changes over time due to mortality or emigration, potentially leaving groups vulnerable to ecological challenges in times of flux. In some societies, the loss of important individuals (e.g., leaders, elites, queens) may have an especially detrimental effect on groups' ability to deal with these challenges. Here, we test whether the removal of queens in colonies of the acorn ant Temnothorax curvispinosus alters their ability to execute important collective behaviors and survive outbreaks of a generalist entomopathogen. We employed a split-colony design where one half of a colony was maintained with its queen, while the other half was separated from the queen. We then tested these subcolonies' performance in a series of collective behavior assays and finally exposed colonies to the entomopathogenic fungus Metarhizium robertsii by exposing two individuals from the colony and then sealing them back into the nest. We found that queenright subcolonies outperformed their queenless counterparts in nearly all collective behaviors. Queenless subcolonies were also more vulnerable to mortality from disease. However, queenless groups that displayed more interactions with brood experienced greater survivorship, a trend not present in queenright subcolonies. Queenless subcolonies that engage in more brood interactions may have had more resources available to cope with two physiological challenges (ovarian development after queen loss and immune activation after pathogen exposure). Our results indicate that queen presence can play an integral role in colony behavior, survivorship, and their relationship. They also suggest that interactions between workers and brood are integral to colonies survival. Overall, a social group's history of social reorganization may have strong consequences on their collective behaviors and their vulnerability to disease outbreaks.
Data from: The Black Queen Hypothesis: evolution of dependencies through adaptive gene loss
Reductive genomic evolution is common in endosymbiotic bacteria, where it is driven by genetic drift. Genome reduction is less common in free-living organisms, but it has occurred in the numerically dominant open-ocean bacterioplankton Prochlorococcus and Pelagibacter, and in these cases the reduction appears to be driven by natural selection rather than drift. The loss of certain genes in free-living organisms may leave them dependent on co-occurring microbes for the lost metabolic functions. We present the Black Queen Hypothesis (BQH), a novel theory of reductive evolution that explains how selection leads to such dependencies; its name refers to the queen of spades in the game Hearts, where the usual strategy is to avoid taking this card. Gene loss can provide a selective advantage by conserving an organism's limiting resources, provided that the gene's function is dispensable. Many vital genetic functions are leaky, thereby unavoidably producing public goods that are available to the entire community. Such leaky functions are thus dispensable for individuals, provided they are not lost entirely from the community. The BQH predicts that the loss of a costly, leaky function is selectively favored at the individual level and will proceed until the production of public goods is just sufficient to support the equilibrium community; at that point, the benefit of any further loss would be offset by the cost. Evolution in accordance with the BQH thus generates "beneficiaries" of reduced genomic content that are dependent on leaky "helpers," and it may explain the observed non-universality of prototrophy, stress resistance, and other cellular functions in the microbial world.
Data from: Black Queen evolution and trophic interactions determine plasmid survival after the disruption of conjugation network
Mobile genetic elements such as conjugative plasmids are responsible for antibiotic resistant phenotypes in many bacterial pathogens. The ability to conjugate, the presence of antibiotics and ecological interactions all have a notable role in the persistence of plasmids in bacterial populations. Here, we set out to investigate the contribution of these factors when the conjugation network was disturbed by a plasmid-dependent bacteriophage. Phage alone effectively caused the population to lose plasmids, thus rendering them susceptible to antibiotics. Leakiness of the antibiotic resistance mechanism allowing Black Queen evolution (i.e. race to the bottom) was a more significant factor over antibiotic concentration (lethal vs sub-lethal) in determining plasmid prevalence. Interestingly, plasmid loss was also prevented by protozoan predation. These results show that the outcome of attempts to re-sensitize bacterial communities by disrupting the conjugation network are highly dependent on ecological factors and resistance mechanisms.
Data from: Eco-evolutionary feedback promotes Red Queen dynamics and selects for sex in predator populations
Although numerous hypotheses exist to explain the overwhelming presence of sexual reproduction across the tree of life, we still cannot explain its prevalence when considering all inherent costs involved. The Red Queen hypothesis states that sex is maintained because it can create novel genotypes with a selective advantage. This occurs when the interactions between species induce frequent environmental change. Here we investigate whether coevolution and eco-evolutionary feedback dynamics in a predator-prey system allows for indirect selection and maintenance of sexual reproduction in the predator. Combining models and chemostat experiments of a rotifer-algae system we show a continuous feedback between population and trait change along with recurrent shifts from selection by predation and competition for a limited resource. We found that a high propensity for sex was indirectly selected and was maintained in rotifer populations within environments containing these eco-evolutionary dynamics; whereas within environments under constant conditions, predators evolved rapidly to lower levels of sex. Thus, our results indicate that the influence of eco-evolutionary feedback dynamics on the overall evolutionary change has been underestimated.
Data from: Hill-Robertson interference maintained by red queen dynamics favours the evolution of sex
Although it is well established theoretically that selective interference among mutations (Hill-Robertson interference) favours meiotic recombination, genome-wide mean rates of mutation and strengths of selection appear too low to support this as the mechanism favouring recombination in nature. A possible solution to this discrepancy between theory and observation is that selection is at least intermittently very strong due to the antagonistic coevolution between a host and its parasites. The Red Queen theory posits that such coevolution generates fitness epistasis among loci, which generates negative linkage disequilibrium among beneficial mutations, which in turn favours recombination. This theory has received only limited support. However, Red Queen dynamics without epistasis may provide the ecological conditions that maintain strong and frequent selective interference in finite populations that indirectly selects for recombination. This hypothesis is developed here through the simulation of Red Queen dynamics. This approach required the development of a method to calculate the exact frequencies of multi-locus haplotypes after recombination. Simulations show that recombination is favoured by the moderately weak selection of many loci involved in the interaction between a host and its parasites, which results in substitution rates that are compatible with empirical estimates. The model also reproduces the previously reported rapid increase in the rate of outcrossing in Caenorhabditis elegans coevolving with a bacterial pathogen.
Data from: Coexistence of evolving bacteria stabilized by a shared Black Queen function
The Black Queen Hypothesis (BQH) was originally proposed to explain the dependence of some marine bacteria on helper organisms for protection from hydrogen peroxide (HOOH). The BQH predicts that selection for the evolutionary loss of leaky functions from individuals can produce commensal or mutualistic interactions. We demonstrated the leakiness of HOOH detoxification by complementing a HOOH-sensitive Escherichia coli mutant with a plasmid-encoded HOOH-detoxifying enzyme, KatG, and then evolving populations founded by this strain in two environments. When HOOH was absent, plasmid-carrying cells were outcompeted by plasmid-free segregants, reflecting the high cost of KatG expression. However, plasmid-carrying and plasmid-free cells coexisted for at least 1,200 generations in three replicate populations evolved in the presence of HOOH, although their relative proportions fluctuated as beneficial mutations arose in one type or the other. Evolved plasmid-bearing cells reduced the cost of plasmid carriage even as they increased the rate of HOOH removal relative to the ancestor. Meanwhile, plasmid-free cells remained dependent on HOOH detoxification by the plasmid-bearing cells. These results demonstrate that partitioning of a Black Queen function can enable the stable coexistence of very similar organisms, even in this most restrictive case where the two types are competing for a single resource.
Data from: Mating with an allopatric male triggers immune response and decreases longevity of ant queens
In species with lifelong pair bonding, the reproductive interests of the mating partners are aligned, and males and females are expected to jointly maximize their reproductive success. Mating increases both longevity and fecundity of female reproductives (queens) of the ant Cardiocondyla obscurior, indicating a tight co-evolution of mating partners. Here, we show that mating with a male from their own population increases lifespan and reproductive success of queens more than mating with a male from a different population, with whom they could not co-evolve. A comparison of transcriptomes revealed an increased expression of genes involved in immunity processes in queens, which mated with males from a different population. Increased immune response might be proximately associated with decreased lifespan. Our study suggests a synergistic co-evolution between the sexes and sheds light on the proximate mechanisms underlying the decreased fitness of allopatrically mated queens.
Data from: Effects of neonicotinoid insecticide exposure and monofloral diet on nest-founding bumblebee queens
Bumblebees are among the world's most important groups of pollinating insects in natural and agricultural ecosystems. Each spring, queen bumblebees emerge from overwintering and initiate new nests, which ultimately give rise to workers and new reproductives later in the season. Nest initiation and survival are thus key drivers of both bumblebee pollination services and population dynamics. We performed the first laboratory experiment with the model bumblebee species Bombus impatiens that explores how early nesting success is impacted by the effects of temporary or more sustained exposure to sublethal levels of a neonicotinoid-type insecticide (imidacloprid at 5 ppb in nectar) and by reliance on a monofloral pollen diet, two factors that have been previously implicated in bumblebee decline. We found that queens exhibited increased mortality and dramatically reduced activity levels when exposed to imidacloprid, as well as delayed nest initiation and lower brood numbers in the nest, but partially recovered from these effects when they only received early, temporary exposure. The effects of pollen diet on individual queen- and colony-level responses were overshadowed by effects of the insecticide, although a monofloral pollen diet alone was sufficient to negatively impact brood production. These findings speak to the sensitivity of queen bumblebees during the nest initiation phase of the colony cycle, with implications for how queens and their young nests are uniquely impacted by exposure to threats such as pesticide exposure and foraging habitat unsuitability.
Data from: No evidence for social immunity in co-founding queen associations
Ant queens often associate to found new colonies, yet the benefits of this behaviour remain unclear. A major hypothesis is that queens founding in groups are protected by social immunity and can better resist disease than solitary queens, due to mutual grooming, sharing of antimicrobials, or higher genetic diversity among their workers. We tested this hypothesis by manipulating the number of queens in incipient colonies of Lasius niger and measuring their resistance to the fungal entomopathogen Metarhizium brunneum. We found no evidence for social immunity in associations of founding queens. First, co-founding queens engaged in self-grooming, but performed very little allo-grooming or trophallaxis. Second, co-founding queens did not exhibit higher pathogen resistance than solitary queens, and their respective workers did not differ in disease resistance. Finally, queens founding in groups increased their investment in a component of individual immunity, as expected if they do not benefit from social immunity but respond to a higher risk of disease. Overall, our results provide no evidence that joint colony founding by L. niger queens increases their ability to resist fungal pathogens.
Data from: Royal Darwinian demons: enforced changes in reproductive efforts do not affect the life expectancy of ant queens
One of the central tenets of life-history theory is that organisms cannot simultaneously maximize all fitness components. This results in the fundamental trade-off between reproduction and life span known from numerous animals, including humans. Social insects are a well-known exception to this rule: reproductive queens outlive nonreproductive workers. Here, we take a step forward and show that under identical social and environmental conditions the fecundity-longevity trade-off is absent also within the queen caste. A change in reproduction did not alter life expectancy, and even a strong enforced increase in reproductive efforts did not reduce residual life span. Generally, egg-laying rate and life span were positively correlated. Queens of perennial social insects thus seem to maximize at the same time two fitness parameters that are normally negatively correlated. Even though they are not immortal, they best approach a hypothetical "Darwinian demon" in the animal kingdom.
Data from: Transcriptomic response to injury sheds light on the physiological costs of reproduction in ant queens
The trade-off between reproduction and longevity is widespread among multicellular organisms. As an important exception, the reproductive females of perennial social insects (ants, honeybees, termites) are simultaneously highly fertile and very long-lived relative to their nonreproductive nestmates. The observation that increased fecundity is not coupled with decreased lifespan suggests that social insect queens do not have to reallocate resources between reproduction and self-maintenance. If queens have to compensate for the costs of reproduction on the level of the individual, the activation of other energy-demanding physiological processes might force them to reduce the production of eggs. To test this hypothesis in ant queens, we increased immunity costs by injury and measured the effect of this treatment on egg-laying rates and genomewide gene expression. Amputation of both middle legs led to a temporary decrease in egg-laying rates and affected the expression of 947 genes corresponding to 9% of the transcriptome. The changes comprised the upregulation of the immune and wound healing response on the one hand, and the downregulation of germ cell development, central nervous system development and learning ability on the other hand. Injury strongly influenced metabolism by inducing catabolism and repressing amino acid and nitrogen compound metabolism. By comparing our results to similar transcriptomic studies in insects, we found a highly consistent upregulation of immune genes due to sterile and septic wounding. The gene expression changes, complemented by the temporary decline of egg-laying rates, clearly reveal a trade-off between reproduction and the immune response in social insect queens.
Cross-activity of honeybee queen pheromones in bumblebees provides evidence for sensory exploitation
<p>The evolutionary origin of queen pheromones, which regulate reproductive division of labor in insect societies, has been explained by two evolutionary scenarios: the <i>sender-precursor hypothesis</i> and the <i>sensory exploitation hypothesis</i>. These scenarios differ in terms of whether the signaling system was built on preadaptations on the part of either the sender queens or the receiver workers. While some social insect queen pheromones – such as cuticular hydrocarbons – were likely derived from ancestral fertility cues and evolved according to the former theory, the honeybee's queen mandibular pheromone (QMP) has been suggested to act directly on pre-existing gene-regulatory networks linked with reproduction. This is evidenced by the fact that QMP has been shown to also inhibit ovary activation in fruit flies, thereby implying exploitation of conserved physiological pathways. To verify whether QMP has similar effects on more closely related eusocial species, we here tested for QMP cross-activity in the bumblebee <i>Bombus terrestris</i>. Interestingly, we found that the non-native QMP blend significantly inhibited egg-laying in both worker and queen bumblebees and caused accompanying shifts in ovary activation. The native bumblebee queen pheromone pentacosane, by contrast, only inhibited the reproduction of the workers. Overall, these findings support the hypothesis that honeybee QMP likely evolved via a route of sensory exploitation. We argue that such exploitation could allow social insect queens to produce compounds that manipulate the workers to remain sterile, but that a major hurdle would be that the queens themselves would have to be immune to such compounds.</p>
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Allen Brain Atlas
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DANDI Archive for NWB datasets
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International Brain Laboratory public data
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OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.