Biology subjects

Majoe, M.

Publications and source records attributed to Majoe, M..

3 recordsLinked to original sources

bioRxiv2024

Queen number shapes worker longevity, fecundity and gene expression in the invasive, highly polygynous ant Tapinoma magnum

In social animals, reproductive activity and ageing patterns are influenced by group composition. A well-documented phenomenon in monogynous (one-queen) insect societies is that queen presence affects worker fecundity and longevity. Little is known about whether and how workers respond to queen number variation in polygynous (multi-queen) species and how their queens age. We created queenless, one-queen, and two-queen colonies of the invasive, polygynous ant Tapinoma magnum to examine worker survival, fecundity, oxidative stress resistance, and fat body gene expression. Additionally, we compared fecundity and brain and fat body transcriptomes of young and old queens. Queenless workers experienced the highest mortality, contrasting with monogynous species where queen removal typically extends lifespan. Workers in single-queen colonies lived longer and were more fertile than in two-queen colonies. Queen number did not directly affect oxidative stress resistance or fat body transcription, though the latter depended on an interaction with worker task. Furthermore, younger nurses demonstrated higher fecundity, oxidative stress resistance and upregulated antioxidant genes compared to older foragers. Absent or minor shifts in fecundity and transcription with queen age, respectively, indicated physiological stability with age. Our research highlights distinct caste- and tissue-specific ageing patterns in this supercolonial species, deviating from typical monogynous ants.

evolutionary biology↗

bioRxiv2024

Queen loss fails to elicit physiological and transcriptional responses in workers of the invasive garden ant Lasius neglectus

Insect colonies with morphologically distinct castes have been called superorganisms because their queens and workers are functionally analogous to the germline and soma in metazoan bodies. In the haplodiploid ants, workers typically lost the sperm storage organ but retained ovaries so they can lay unfertilized eggs. Worker reproduction often occurs after queen loss and is accompanied by a number of physiological changes. However, in some evolutionarily derived ants, workers have become functionally sterile and in many of these species colonies contain multiple queens and can readily raise replacement queens - a syndrome characteristic for invasive ants. We hypothesized that the combination of full worker sterility and regular queen replacement should have eliminated important aspects of the physiological interdependence between queens and workers. We tested this hypothesis by analysing fat body gene expression and worker resistance to oxidative stress in colonies of the invasive ant Lasius neglectus with and without queens. We found age-related transcriptional shifts between young and old queens and young and old workers, suggesting rapid ageing in all castes. However, the removal of any queens in controlled experiments failed to elicit changes in the transcriptional activity and oxidative stress resistance of workers, consistent with our hypothesis. The invasive syndrome of this ant may thus have led to a somatic work force that evolved to be physiologically independent of queen presence.

evolutionary biology↗

bioRxiv2023

Task-specific patterns of odorant receptor expression in worker antennae indicates a sensory filter regulating division of labor in ants

Division of labor (DOL) is a characteristic trait of insect societies, where tasks are generally performed by groups of specialized individuals. In social insects, young workers perform duties within the safety of the nest (e.g., brood care), while older ones undertake riskier tasks (e.g., foraging for food). This DOL remains dynamic, and workers may switch back and forth when colony needs require. Theoretical models propose that workers differ in their thresholds to take on certain tasks when confronted to task-related stimuli, resulting in variation in their response to such stimuli, task-specialization, and thus DOL. Such models assume that workers differ in how they respond to task-related information rather than in how they perceive such information. Here, we test the hypothesis that DOL rather stems from workers differing in their efficiency to detect task-related stimuli. We used transcriptomics to compare gene expression in the antennae and in the brain between nurses and foragers in the ant Temnothorax longispinosus. We found that seven times as many genes were differentially expressed between the behavioral phenotypes in the antennae compared to the brain. Moreover, nearly half of all odorant receptors genes were differentially expressed, with an overrepresentation of the 9-exon gene subfamily upregulated in the antennae of nurses. These findings suggest that nurses and foragers differ in how they perceive their olfactory environment, and task-related signals. The results of this study support the hypothesis that a sensory filter in the antennaepredisposes workers to specialize in specific tasks, and may improve our understanding of DOL in insect societies.

evolutionary biology↗