Neurobiology and Behavior Research

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This is a collection of research articles and datasets concerning aspects of Neurobiology and Behavior.


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    Data and Script from: Reducing childhood mortality extends mothers’ lives
    Zipple, Matthew (2024)
    During the 20th century, childhood mortality was dramatically reduced globally, falling by more than 90% in the United States and much of Europe. Total fertility also fell, with the combined result that many parents who otherwise would have experienced the loss of a child were spared the trauma and negative health consequences that accompany such a loss. Here I use mathematical modeling to argue that the reduction in the frequency of child death that occurred in the 20th century indirectly led to a substantial reduction in female mortality, resulting in an extension of female lifespan. I estimate that the reduction in maternal bereavement in the US during the 20th century indirectly increased mean female lifespan after age 15 by approximately 1 year. I discuss implications for our understanding of the persistence of the sex gap in longevity and approaches to improving maternal health outcomes in countries that still face high levels of childhood mortality.
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    Cuticular and Glandular Chemistry of Megalopta genalis
    Kingwell, Callum; Böröczky, Katalin; Steitz, Iris; Ayasse, Manfred; Wcislo, William (2020)
    These data are from the analysis of cuticular and Dufour’s gland chemistry across alternative social phenotypes within a population of facultatively eusocial Megalopta genalis bees (tribe Augochlorini, family Halictidae). Reproductive bees (queens and solitary reproductives) have distinct glandular and cuticular chemical phenotypes compared with non-reproductive workers. On the cuticle, a likely site of signal transmission, reproductives are enriched for certain alkenes, most linear alkanes, and heavily enriched for all methyl-branched alkanes; these compound classes have known functions as fertility signals among other eusocial insect taxa. Some macrocyclic lactones, compounds that function as queen pheromones in the other eusocial halictid tribe (Halictini), are also enriched among reproductives relative to workers. The intra-population facultative eusociality of M. genalis permits direct comparisons between individuals expressing alternative reproductive phenotypes – females that reproduce alone (solitary reproductives) and social queens – to highlight traits in the latter that are potentially important for eusocial organization. Compared with solitary reproductives, the cuticular chemistries of queens are more strongly differentiated from those of workers and are especially enriched for methyl-branched alkanes. Determining the pheromonal function(s) and information content of the candidate signaling compounds identified will aid in illuminating the early evolutionary history of queen pheromones, chemical signals central to the organization of insect eusociality.
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    Data from: Artificial shaking signals in honey bee colonies elicit natural responses
    Koenig, Phoebe A; Smith, Michael L; Horowitz, Logan H; Palmer, Daniel M; Petersen, Kirstin H (2020)
    Honey bee signals are primarily studied through natural observation combined with manipulations of the colony or environment, not direct manipulation of the signal stimulus or receivers. Consequently, we know little about which signal aspects are necessary to reproduce behavioral responses. Here, we focus on the shaking signal, wherein a worker grabs onto another bee and vibrates. All castes receive shaking signals, but individual responses depend on context, and the signal may be multi-modal (mechanical, odor, sound, etc.). We designed a tool to mimic the shaking signal. We tested whether a purely mechanical stimulus elicited the same behavioral response as a natural shaking signal, teasing apart the effects of signal and receiver characteristics. We found that both workers and drones increased their movement after being artificially shaken, and that shaken drones were more likely to engage in feeding and grooming than a sham control. These behavioral changes support the idea that the shaking signal serves to generally increase worker activity, but also serves to activate male reproductives (drones). With this tool, we show that vibration itself is responsible for eliciting much of the shaking signal's behavioral response, in one of the few examples of direct playback in social insects.
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    Data from: Response of Wild Spotted Wing Drosophila (Drosophila suzukii) to Microbial Volatiles
    Bueno, Eduardo; Martin, Kyle R; Raguso, Robert A; McMullen, John G II; Hesler, Stephen P; Loeb, Greg M; Douglas, Angela E (2019)
    The olfactory cues used by various animals to detect and identify food items often include volatile organic compounds (VOCs) produced by food-associated microorganisms. Microbial VOCs have potential as lures to trap animal pests, including insect crop pests. This study investigated microorganisms whose VOCs are attractive to natural populations of the spotted wing drosophila (SWD), an invasive insect pest of ripening fruits. The microorganisms readily cultured from wild SWD and SWD-infested fruits included yeasts, especially Hanseniaspora species, and various bacteria, including Proteobacteria (especially Acetobacteraceae and Enterobacteriaceae) and Actinobacteria. Traps in a raspberry planting that were baited with cultures of Hanseniaspora uvarum, H. opuntiae and the commercial lure Scentry trapped relatively high numbers of both SWD and non-target drosophilids. The VOCs associated with these baits were dominated by ethyl acetate and, for yeasts, other esters. By contrast, Gluconobacter species (Acetobacteraceae), whose VOCs were dominated by acetic acid and acetoin and lacked detectable ethyl acetate, trapped 60-75% fewer SWD but with very high selectivity for SWD. VOCs of two other taxa tested, the yeast Pichia sp. and Curtobacterium sp. (Actinobacteria), trapped very few SWD or other insects. Our demonstration of among microbial variation in VOCs and their attractiveness to SWD and non-pest insects under field conditions provides the basis for improved design of lures for SWD management. Further research is required to establish how different microbial VOC profiles may function as reliable cues of habitat suitability for fly feeding and oviposition, and how this variation maps onto among-insect species differences in habitat preference.
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    Data from: Queenless honey bees build infrastructure for direct reproduction until their new queen proves her worth
    Smith, Michael L (2018)
    The terminal investment hypothesis predicts that individuals will alter their reproductive investments based on reproductive prospects. This hypothesis, however, has never been tested at the colony-level, where reproductive prospects for thousands of individuals can change instantly with the death of a single individual: the queen. A honey bee queen’s death also changes the reproductive mechanism; if the queen is not replaced, then workers reproduce directly, by producing males in reproductive comb – drone comb – before the colony dies. To test how workers respond to reproductive uncertainty, I made colonies queenless and measured comb building throughout the stages of rearing a replacement queen. Queenless workers built only drone comb throughout queen rearing, even when the colony possessed a virgin or mated queen. Only when the new queen started laying fertilized eggs did workers stop building drone comb. Despite queenless colonies being more likely to eventually rear a replacement queen (88%), than to fail (12%), workers still built drone comb for direct reproduction, even when the colony was provided with ample drone comb. Therefore, workers “pessimistically” invest in drone comb to prepare for direct reproduction, even while rearing a replacement queen to prevent that outcome. When faced with reproductive uncertainty, honey bees may “hope” for the best, but they prepare for the worst. This dataset supports the conclusions expressed in this paper.
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    Data from: "Larger but not louder: bigger honey bee colonies have quieter combs”
    Smith, Michael L; Chen, Po-Cheng (2017-10-02)
    Communication is impossible if the sender’s signal cannot overcome background noise to reach the receiver. This obstacle is present in all communication modalities, forcing organisms to develop diverse mechanisms to overcome noise. Honey bees will modify combs to improve signal efficiency of substrate-borne vibrations, but it is unknown whether, and if so, how, bees compensate for the largest potential source of noise: the bees themselves. The number of bees in a colony changes markedly throughout the year, but the size of the nest cavity does not, forcing workers into high densities on the combs. How, then, do bees communicate via substrate-borne vibrations on combs that are covered in bees? We used accelerometers to measure comb vibrations, while varying the number of workers on the comb. Surprisingly, comb vibrations decreased with increased worker number. Furthermore, inserting freshly killed bees to the comb demonstrated that it is not simply the bees’ collective mass that damps vibrations, but is probably their behavior. We propose that their posture damps vibrations, with each bee linking up to six neighboring cells with her legs. This collective damping reduces background noise, and improves the landscape for communication. These results demonstrate how living systems, including superorganisms, can overcome physical obstacles with curiously simple and elegant solutions.
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    Data from: The behavioral regulation of thirst, water collection, and water storage in honey bee colonies
    Ostwald, Madeleine M; Smith, Michael L; Seeley, Thomas D (2016)
    This data is from a study that investigates how a honey bee colony develops and quenches its collective thirst when it experiences hyperthermia of its broodnest, the nest region whose temperature and humidity are precisely regulated. We found that in this emergency situation a colony must strongly boost its water intake because evaporative cooling is critical to avoiding broodnest hyperthermia, and it must rapidly boost its water intake because a colony maintains only a small water reserve. We also shed light on how the worker bees functioning as water collectors know when to spring into action—by sensing either more frequent requests for fluid or greater personal thirst, or both—and we demonstrate that this sensing mechanism is sufficiently fine-tuned to prevent overheating and desiccation of the colony's brood. Finally, we found that the impressive behavioral flexibility of a colony's water collectors enables them not only to satisfy their colony's current water needs, but also to buffer their colony somewhat against future extreme water stresses by storing water in their crops and in the combs.
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    Data from: How Honey Bee Colonies Survive in the Wild: Testing the Importance of Small Nests and Frequent Swarming
    Loftus, J Carter; Smith, Michael L; Seeley, Thomas D (2016)
    The ectoparasitic mite, Varroa destructor, and the viruses that it transmits, kill the colonies of European honey bees (Apis mellifera) kept by beekeepers unless the bees are treated with miticides. Nevertheless, there exist populations of wild colonies of European honey bees that are persisting without being treated with miticides. We hypothesized that the persistence of these wild colonies is due in part to their habits of nesting in small cavities and swarming frequently. We tested this hypothesis by establishing two groups of colonies living either in small hives (42 L) without swarm- control treatments or in large hives (up to 168 L) with swarm-control treatments. We followed the colonies for two years and compared the two groups with respect to swarming frequency, Varroa infesttion rate, disease incidence, and colony survival. Colonies in small hives swarmed more often, had lower Varroa infestation rates, had less disease, and had higher survival compared to colonies in large hives. These results indicate that the smaller nest cavities and more frequent swarming of wild colonies contribute to their persistence without mite treatments. This item is the dataset underlying this project.
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    The Collapse Times of Tall Multi-story buildings of Constant Cross-scection
    Howland, Bradford; Howland, Frank M.; Howland, Howard C. (2012-02-03)
    We present a simple mathematical model of the collapse of tall multistory buildings in general and of the world trade center (WTC) towers in particular with the object of predicting the collapse times. In constructing the model we first considered two modes of demolition, one in which the supports of the bottom floor are destroyed and a second where the supports of the topmost level are destroyed. In both modes it is assumed that the retardation of the brittle structure of the building is insignificant. In the first model the entire building collapses in freefall, i.e. with one g acceleration. In the second mode of collapse we show that for very tall buildings the ratio of the time for collapse and the freefall time, as well as the reciprocal velocities of collapse, approach the square root of three as the number of floors is increased indefinitely. We then model the destruction of the WTC towers and the combination of the two modes of collapse. In this third mode of collapse the destruction of the building results in an agglomeration of floors impacted from the top by freefalling floors and impacting the lower floors below it. It may be shown that the agglomeration has an acceleration of 3/5 g. The model constructed along these lines for the collapse of the WTC towers, which had fractures originating at different floors, results collapse times that differ by 1.83 seconds. This difference accords well with the measured two second difference in collapse times derived from the video and seismic records.
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    On the Mechanism of the Eye
    Young, Thomas (Philosophical Transactions, 1801)
    Thomas Young was an English physician and a physicist who was responsible for many important theories and discoveries in optics and in human anatomy. This is a paper written by him that describes the mechanism of the eye from 1801.