Biology subjects

Jernigan, C. M.

Publications and source records attributed to Jernigan, C. M..

9 recordsLinked to original sources

bioRxiv2025

Bumblebee queens differ in brain morphology but not learning performance across life stages

Animal cognition and brain morphology can vary between individuals and across a lifetime as a function of social and ecological requirements. Bumblebees have distinct ecological pressures acting upon individuals at different times: young queens (gynes) and workers share similar challenges as they both forage as part of the colony, but only queens overwinter and start a colony the following season, switching to a reproductive stage. Here we compared bumblebee (Bombus impatiens) visual learning and brain morphology across age-matched workers and gynes and older reproductive queens. We expected foraging-stage gynes to be better at visual learning than reproductive queens and visual regions to be reduced in the reproductive queens, in line with work in other social insects. However, we found that gynes and queens performed similarly, while both performed better than workers. We also found that reproductive queens had larger olfactory regions (antennal lobes) than gynes, while visual regions (medulla and lobula) did not differ, indicating a greater investment in olfactory regions in this later reproductive stage. Brain regions also scaled differently with body size for gynes and workers. Overall, our results provide behavioral and morphological evidence that social and ecological roles in a colony shape cognition and neural investment.

animal behavior and cognition↗

bioRxiv2024

Neural correlates of individual facial recognition in a social wasp

Individual recognition is critical for social behavior across species. Whether recognition is mediated by circuits specialized for social information processing has been a matter of debate. Here we examine the neurobiological underpinning of individual visual facial recognition in Polistes fuscatus paper wasps. Front-facing images of conspecific wasps broadly increase activity across many brain regions relative to other stimuli. Notably, we identify a localized subpopulation of neurons in the protocerebrum which show specialized selectivity for front-facing wasp images, which we term wasp cells. These wasp cells encode information regarding the facial patterns, with ensemble activity correlating with facial identity. Wasp cells are strikingly analogous to face cells in primates, indicating that specialized circuits are likely an adaptive feature of neural architecture to support visual recognition. One-Sentence SummaryWe identify a localized population of neurons specifically tuned to wasp faces in a social wasp that has independently evolved individual facial recognition analogous to the face cells of primates.

neuroscience↗

bioRxiv2021

Novelty detection in early olfactory processing of the honey bee, Apis mellifera

Animals are constantly bombarded with stimuli, which presents a fundamental problem of sorting among pervasive uninformative stimuli and novel, possibly meaningful stimuli. We evaluated novelty detection behaviorally in honey bees as they position their antennae differentially in an air stream carrying familiar or novel odors. We then characterized neuronal responses to familiar and novel odors in the first synaptic integration center in the brain - the antennal lobes. We found that the neurons that exhibited stronger initial responses to the odor that was to be familiarized are the same units that later distinguish familiar and novel odors, independently of chemical identities. These units, including both projection neurons and local neurons, showed a decreased response to the familiar odor but an increased response to the novel odor. Our results suggest that the antennal lobe may assign a category of familiarity or novelty to an odor stimulus in addition to its chemical identity code. Therefore, the mechanisms for novelty detection may be present in early sensory processing, either as a result of local synaptic interaction or via feedback from higher brain centers.

neuroscience↗

bioRxiv2021

Color is necessary for specialized face learning in the Northern paper wasp, Polistes fuscatus

Visual individual recognition requires animals to distinguish among conspecifics based on appearance. Though visual individual recognition has been reported in a range of taxa, the features that animals rely on to discriminate between individuals are often not well understood. Northern paper wasp females, Polistes fuscatus, possess individually distinctive color patterns on their faces, which mediate individual recognition. It is currently unclear what facial features P. fuscatus use to distinguish individuals. The anterior optic tubercle, a chromatic processing brain region, is especially sensitive to social experience during development, suggesting that color may be important for recognition in this species. We sought to test the roles of color in wasp facial recognition. Color may be important simply because it creates a pattern. If this is the case, then wasps should perform similarly when discriminating color or grayscale images of the same faces. Alternatively, color itself may be important for recognition, which would predict poorer performance on grayscale image discrimination relative to color images. We found wasps trained on grayscale faces, unlike those trained on color images, did not perform better than chance. Suggesting that color is necessary for the recognition of an image as a face by the wasp visual system.

animal behavior and cognition↗

bioRxiv2021

Evidence for a selective link between cooperation and individual recognition

The ability to recognize and discriminate among others is a frequent assumption of models of the evolution of cooperative behavior. At the same time, cooperative behavior has been proposed as a selective agent favoring the evolution of individual recognition abilities. While theory predicts that recognition and cooperation may co-evolve, data linking recognition abilities and cooperative behavior with fitness or evidence of selection are elusive. Here, we provide evidence of a fitness link between individual recognition and cooperation in the paper wasp Polistes fuscatus. Nest founding females in northern populations frequently form cooperative multiple foundress nests and possess highly variable facial patterns that mediate individual recognition. We describe a dearth of cooperative nesting, low phenotypic diversity, and a lack of individual recognition in southern populations. In a common garden experiment, northern co-foundress associations successfully reared offspring while all cooperative southern groups failed to rear any offspring, suggesting a fitness link between individual recognition and successful cooperation. Consistent with a selective link between individual recognition and cooperation, we find that rates of cooperative co-nesting correlate with identity-signaling color pattern diversity across the species range. Moreover, genomic evidence of recent positive selection on cognition loci likely to mediate individual recognition is substantially stronger in northern compared to southern P. fuscatus populations. Collectively, these data suggest that individual recognition and cooperative nesting behavior have co-evolved in P. fuscatus because recognition helps mediate conflict among co-nesting foundresses. This work provides evidence of a specific cognitive phenotype under selection because of social interactions, supporting the idea that social behavior can be a key driver of cognitive evolution.

animal behavior and cognition↗

bioRxiv2021

Dynamic neurogenomic responses to social interactions and dominance outcomes in female paper wasps

Social interactions have large effects on individual physiology and fitness. In the immediate sense, social stimuli are often highly salient and engaging. Over longer time scales, competitive interactions often lead to distinct social ranks and differences in physiology and behavior. Understanding how initial responses lead to longer-term effects of social interactions requires examining the changes in responses over time. Here we examined the effects of social interactions on transcriptomic signatures at two points, at the end of a 45-minute interaction and 4 hours later, in female Polistes fuscatus paper wasp foundresses. Female P. fuscatus have variable facial patterns that are used for visual individual recognition, so we separately examined the transcriptional dynamics in the optic lobe and the central brain. Results demonstrate much stronger transcriptional responses to social interactions in the central brain compared to the optic lobe. Differentially regulated genes in response to social interactions are enriched for memory-related transcripts. Comparisons between winners and losers of the encounters revealed similar overall transcriptional profiles at the end of an interaction, which significantly diverged over the course of 4 hours, with losers showing changes in expression levels of genes associated with aggression and reproduction in paper wasps. On nests, subordinate foundresses are less aggressive, do more foraging and lay fewer eggs compared to dominant foundresses and we find losers shift expression of many genes, including vitellogenin, related to aggression, worker behavior, and reproduction within hours of losing an encounter. These results highlight the early neurogenomic changes that likely contribute to behavioral and physiological effects of social status changes in a social insect.

genomics↗

bioRxiv2020

Expansion and accelerated evolution of 9-exon odorant receptors in Polistes paper wasps (Hymenoptera: Vespidae)

Independent origins of sociality in bees and ants are associated with independent expansions of particular odorant receptor (OR) gene subfamilies. In ants, one clade within the OR gene family, the 9-exon subfamily, has dramatically expanded. These receptors detect cuticular hydrocarbons (CHCs), key social signaling molecules in insects. It is unclear to what extent 9-exon OR subfamily expansion is associated with the independent evolution of sociality across Hymenoptera, warranting studies of taxa with independently derived social behavior. Here we describe odorant receptor gene family evolution in the northern paper wasp, Polistes fuscatus, and compare it to four additional paper wasp species spanning ~40 million years of divergence. We find 200 functional OR genes in P. fuscatus matching predictions from neuroanatomy, and more than half of these are in the 9-exon subfamily. Lineage-specific expansions of 9-exon subfamily ORs are tandemly arrayed in Polistes genomes and exhibit a breakdown in microsynteny relative to tandem arrays in other OR subfamilies. There is evidence of episodic positive diversifying selection shaping ORs in expanded subfamilies, including 9-exon, E, H, and L, but 9-exon ORs do not stand out as selectively diversified among Polistes species. Accelerated evolution has resulted in lower amino acid similarity and high dN/dS among 9-exon ORs compared to other OR subfamilies. Patterns of OR evolution within Polistes are consistent with 9-exon OR function in CHC perception by combinatorial coding, with both selection and drift contributing to interspecies differences in copy number and sequence.

evolutionary biology↗

bioRxiv2019

Experience-dependent tuning of early olfactory processing in the adult brain

Experience-dependent plasticity in the central nervous system allows an animal to adaptively change their responses to stimuli over different time scales. In this study we explored the different time frames and mechanisms over which olfactory experience-dependent plasticity works. We measured the impact of experience on early olfactory processing by comparing naturally foraging animals with a diverse olfactory experience to animals from the same cohort that experienced a chronic reduction in adult olfactory experience. We placed age-matched sets of full-sister honey bees, Apis mellifera, into two different olfactory conditions, in which animals were allowed to forage ad libitum. In one condition (T), we reduced the olfactory experience of foraging bees by placing them in a tent in which both sucrose and pollen resources were associated with a single odor. In the second condition (F), bees were allowed to forage freely and therefore receive a diversity of naturally occurring resource-associated olfactory experiences. We found that bees with a reduced olfactory experience had less developed antennal lobes when compared to experienced foragers, suggesting early-adult sensory experience influences the development of olfactory processing. We next measured the antennal lobe glomerular responses to odors using calcium imaging, and found that diverse olfactory experience of bees also enhances the inter-individual variation in the glomerular response profiles to odors. Last, we measured the impact of this treatment in an olfactory learning assay. We found that bees with a reduced olfactory experience had more difficulty picking an odor out of a mixture, which led them to generalize more (or respond similarly) to different mixture components than bees with richer olfactory experiences. Our study highlights the impact of individual experience at multiple levels (i.e., behavioral, physiological, developmental) on early olfactory processing.

neuroscience↗

bioRxiv2017

SwarmSight: Real-Time Tracking of Insect Antenna Movements and Proboscis Extension Reflex using a Common Preparation and Conventional Hardware

Many scientifically and agriculturally important insects use antennae to detect the presence of volatile chemical compounds and extend their proboscis during feeding. The ability to rapidly obtain high-resolution measurements of natural antenna and proboscis movements and assess how they change in response to chemical, developmental, and genetic manipulations can aid the understanding of insect behavior. By extending our previous work on assessing aggregate insect swarm or animal group movements from natural and laboratory videos using video analysis software SwarmSight, we developed a novel, free, and open-source software module, SwarmSight Appendage Tracking (SwarmSight.org) for frame-by-frame tracking of insect antenna and proboscis positions from conventional web camera videos using conventional computers. The software processes frames about 120 times faster than humans, performs at better than human accuracy, and, using 30 frames-per-second videos, can capture antennal dynamics up to 15 Hz. We used the software to track the antennal response of honey bees to two odors and found significant mean antennal retractions away from the odor source about 1 s after odor presentation. We observed antenna position density heat map cluster formation and cluster and mean angle dependence on odor concentration.

animal behavior and cognition↗