Matching Items (17)
Description
Social insect colonies exhibit striking diversity in social organization. Included in this overwhelming variation in structure are differences in colony queen number. The number of queens per colony varies both intra- and interspecifically and has major impacts on the social dynamics of a colony and the fitness of its members. To understand the evolutionary transition from single to multi-queen colonies, I examined a species which exhibits variation both in mode of colony founding and in the queen number of mature colonies. The California harvester ant Pogonomyrmex californicus exhibits both variation in the number of queens that begin a colony (metrosis) and in the number of queens in adult colonies (gyny). Throughout most of its range, colonies begin with one queen (haplometrosis) but in some populations multiple queens cooperate to initiate colonies (pleometrosis). I present results that confirm co-foundresses are unrelated. I also map the geographic occurrence of pleometrotic populations and show that the phenomenon appears to be localized in southern California and Northern Baja California. Additionally, I provide genetic evidence that pleometrosis leads to primary polygyny (polygyny developing from pleometrosis) a phenomenon which has received little attention and is poorly understood. Phylogenetic and haplotype analyses utilizing mitochondrial markers reveal that populations of both behavioral types in California are closely related and have low mitochondrial diversity. Nuclear markers however, indicate strong barriers to gene flow between focal populations. I also show that intrinsic differences in queen behavior lead to the two types of populations observed. Even though populations exhibit strong tendencies on average toward haplo- or pleometrosis, within population variation exists among queens for behaviors relevant to metrosis and gyny. These results are important in understanding the dynamics and evolutionary history of a distinct form of cooperation among unrelated social insects. They also help to understand the dynamics of intraspecific variation and the conflicting forces of local adaptation and gene flow.
ContributorsOverson, Rick P (Author) / Gadau, Jürgen (Thesis advisor) / Fewell, Jennifer H (Committee member) / Hölldobler, Bert (Committee member) / Johnson, Robert A. (Committee member) / Liebig, Jürgen (Committee member) / Arizona State University (Publisher)
Created2011
Description
For over a century, researchers have been investigating collective cognition, in which a group of individuals together process information and act as a single cognitive unit. However, I still know little about circumstances under which groups achieve better (or worse) decisions than individuals. My dissertation research directly addressed this longstanding question, using the house-hunting ant Temnothorax rugatulus as a model system. Here I applied concepts and methods developed in psychology not only to individuals but also to colonies in order to investigate differences of their cognitive abilities. This approach is inspired by the superorganism concept, which sees a tightly integrated insect society as the analog of a single organism. I combined experimental manipulations and models to elucidate the emergent processes of collective cognition. My studies show that groups can achieve superior cognition by sharing the burden of option assessment among members and by integrating information from members using positive feedback. However, the same positive feedback can lock the group into a suboptimal choice in certain circumstances. Although ants are obligately social, my results show that they can be isolated and individually tested on cognitive tasks. In the future, this novel approach will help the field of animal behavior move towards better understanding of collective cognition.
ContributorsSasaki, Takao (Author) / Pratt, Stephen C (Thesis advisor) / Amazeen, Polemnia (Committee member) / Liebig, Jürgen (Committee member) / Janssen, Marco (Committee member) / Fewell, Jennifer (Committee member) / Hölldobler, Bert (Committee member) / Arizona State University (Publisher)
Created2013
Description
At the heart of every eusocial insect colony is a reproductive division of labor. This division can emerge through dominance interactions at the adult stage or through the production of distinct queen and worker castes at the larval stage. In both cases, this division depends on plasticity within an individual to develop reproductive characteristics or serve as a worker. In order to gain insight into the evolution of reproductive plasticity in the social insects, I investigated caste determination and dominance in the ant Harpegnathos saltator, a species that retains a number of ancestral characteristics. Treatment of worker larvae with a juvenile hormone (JH) analog induced late-instar larvae to develop as queens. At the colony level, workers must have a mechanism to regulate larval development to prevent queens from developing out of season. I identified a new behavior in H. saltator where workers bite larvae to inhibit queen determination. Workers could identify larval caste based on a chemical signal specific to queen-destined larvae, and the production of this signal was directly linked to increased JH levels. This association provides a connection between the physiological factors that induce queen development and the production of a caste-specific larval signal. In addition to caste determination at the larval stage, adult workers of H. saltator compete to establish a reproductive hierarchy. Unlike other social insects, dominance in H. saltator was not related to differences in JH or ecdysteroid levels. Instead, changes in brain levels of biogenic amines, particularly dopamine, were correlated with dominance and reproductive status. Receptor genes for dopamine were expressed in both the brain and ovaries of H. saltator, and this suggests that dopamine may coordinate changes in behavior at the neurological level with ovarian status. Together, these studies build on our understanding of reproductive plasticity in social insects and provide insight into the evolution of a reproductive division of labor.
ContributorsPenick, Clint A (Author) / Liebig, Jürgen (Thesis advisor) / Brent, Colin (Committee member) / Gadau, Jürgen (Committee member) / Hölldobler, Bert (Committee member) / Rutowski, Ron (Committee member) / Arizona State University (Publisher)
Created2012
Description
Humans achieve coordination within and across themselves through the use of coupling. Coupling is the term for an informational linkage that allows two independent processes to eventually coordinate together. Coupling between the motor and respiratory system is evident within people through the signaling of the nervous system. However, little has been known about the degree of coordination that can be attained across two people regarding their respiratory patterns. The current study tested whether unintentional coordination of respiration across two people could be achieved when both people were intentionally coordinating their motor movements. Participants were assigned the position of leader or follower, where the leader followed the rhythm of a metronome to lift their leg to and the follower coordinated their leg-lift with the leader’s using their vision, as instructed. During the experiment the movements of each participant’s knee and their respiration were recorded. Relative phase was used as a measure of coordination. Results show that motor coordination was achieved, consistent with past studies, but that there was no coordination of respiration across the participants. This is most likely due to individual differences in physiology and the lack of coupling between the two separate respiratory systems. Although internal motor-respiratory patterns may have coordinated in a multi-frequency manner within each participant, the outward phasing of their respiration showed no such relationship. This study highlights the importance of a multi-frequency approach when observing coordination within and across physiological systems.
ContributorsHunteman, Zebediah Monroe (Author) / Amazeen, Polemnia (Thesis director) / Amazeen, Eric (Committee member) / Anderson, Samantha (Committee member) / Department of Psychology (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
The human body is a complex system that links mental learning processes and developed muscular capabilities to produce novel movements or refine existing movements. It is well known that skills are learned and become more refined with practice, however motor skills can develop by watching others perform an action. The current study aims to test the utility of videotaped and/or written instructional methods in teaching novice slackliners. Results showed a significant interaction between group and trial. The video+word group had significantly longer balance times than the control and video groups in trial two. The word group had significantly longer balance times than the control and video groups in trials three and four. A cumulative skill score was not found to be significantly correlated with balance times. Limitations of the current study are discussed, as well as recommendations for future study and applications.
ContributorsRoesler, Kimberly Rose (Author) / Amazeen, Polemnia (Thesis director) / Amazeen, Eric (Committee member) / School of Molecular Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Recent work in free-recall tasks suggest that human memory foraging may follow a Lévy flight distribution – a random walk procedure that is common in other activities of cognitive agents, such as animal and human food foraging. This study attempts to draw parallels between memory search and physical search, with the assumption that humans follow similar search patterns in both. To date, research merely equates the two processes (foraging in memory and the physical world) based on a similarity in statistical structure. This study starts with demonstrating a relationship between physical distance traveled and IRIs by having participants list countries. An IRI, inter-retrieval interval, is the time interval between items recalled. The next experiment uses multidimensional scaling (MDS) to derive a Euclidean perceptual space from similarity ratings of freely-recalled items and then maps the trajectory of human thought through this perceptual space. This trajectory can offer a much more compelling comparison to physical foraging behavior. Finally, a possible correlate of Lévy flight foraging is explored called critical slowing down. Statistically significant evidence was found in all three experiments. The discussion connects all three experiments and what their results mean for human memory foraging.
ContributorsGreer, Katharine Marie (Author) / Amazeen, Eric L. (Thesis director) / Glenberg, Arthur (Committee member) / Amazeen, Polemnia (Committee member) / Department of Psychology (Contributor) / School of Criminology and Criminal Justice (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Variability is inherent in human movement, and poses a challenge to researchers attempting to measure balance. Human movement variability was analyzed using two methods: standard deviation and largest Lyapunov exponent. The experiment was a sit-to-stand task with physical and cognitive perturbations. The physical perturbation consisted of stable and unstable platform conditions, while the cognitive perturbation consisted of a counting task. The data were collected from 24 healthy young adults. The purpose of this study was to compare the standard deviation and largest Lyapunov exponent as measures of stability, and to determine the Lyapunov exponent's sensitivity to cognitive perturbation. Evidence suggests that the Lyapunov exponent serves as a more accurate indicator of stability than standard deviation, and that it lacks sensitivity to the counting task.
ContributorsJohnson, Jennifer Jeanne (Author) / Amazeen, Polemnia (Thesis director) / Amazeen, Eric (Committee member) / Stone, Gregory (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The action of running is difficult to measure, but well worth it to receive valuable information about one of our most basic evolutionary functions. In the context of modern day, recreational runners typically listen to music while running, and so the purpose of this experiment is to analyze the influence of music on running from a more dynamical approach. The first experiment was a running task involving running without a metronome and running with one while setting one's own preferred running tempo. The second experiment sought to manipulate the participant's preferred running tempo by having them listen to the metronome set at their preferred tempo, 20% above their preferred tempo, or 20% below. The purpose of this study is to analyze whether or not rhythmic perturbations different to one's preferred running tempo would interfere with one's preferred running tempo and cause a change in the variability of one's running patterns as well as a change in one's running performance along the measures of step rate, stride length, and stride pace. The evidence suggests that participants naturally entrained to the metronome tempo which influenced them to run faster or slower as a function of metronome tempo. However, this change was also accompanied by a shift in the variability of one's step rate and stride length.
ContributorsZavala, Andrew Geovanni (Author) / Amazeen, Eric (Thesis director) / Amazeen, Polemnia (Committee member) / Vedeler, Dankert (Committee member) / Department of Psychology (Contributor) / W. P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Dominance behavior can regulate a division of labor in a group, such as that between reproductive and non-reproductive individuals. Manipulations of insect societies in a controlled environment can reveal how dominance behavior is regulated. Here, I examined how morphological caste, fecundity, group size, and age influence the expression of dominance behavior using the ponerine ant Harpegnathos saltator. All H. saltator females have the ability to reproduce. Only those with a queen morphology that enables dispersal, however, show putative sex pheromones. In contrast, those with a worker morphology normally express dominance behavior. To evaluate how worker-like dominance behavior and associated traits could be expressed in queens, I removed the wings from alate gynes, those with a queen morphology who had not yet mated or left the nest, making them dealate. Compared to gynes with attached wings, dealates frequently performed dominance behavior. In addition, only the dealates demonstrated worker-like ovarian activity in the presence of reproductive individuals, whereas gynes with wings produced sex pheromones exclusively. Therefore, the attachment of wings determines a gyne’s expression of worker-like dominance behavior and physiology. When the queen dies, workers establish a reproductive hierarchy among themselves by performing a combination of dominance behaviors. To understand how reproductive status depends on these interactions as well as a worker’s age, I measured the frequency of dominance behaviors in groups of different size composed of young and old workers. The number of workers who expressed dominance scaled with the size of the group, but younger ones were more likely to express dominance behavior and eventually become reproductive. Therefore, the predisposition of age integrates with a self-organized process to form this reproductive hierarchy. A social insect’s fecundity and fertility signal depends on social context because fecundity increases with colony size. To evaluate how a socially dependent signal regulates dominance behavior, I manipulated a reproductive worker’s social context. Reproductive workers with reduced fecundity and a less prominent fertility signal expressed more dominance behavior than those with a stronger fertility signal and higher fecundity. Therefore, dominance behavior reinforces rank to compensate for a weak signal, indicating how social context can feed back to influence the maintenance of dominance. Mechanisms that regulate H. saltator’s reproductive hierarchy can inform how the reproductive division of labor is regulated in other groups of animals.
ContributorsPyenson, Benjamin (Author) / Liebig, Jürgen (Thesis advisor) / Hölldobler, Bert (Committee member) / Fewell, Jennifer (Committee member) / Pratt, Stephen (Committee member) / Kang, Yun (Committee member) / Arizona State University (Publisher)
Created2022
Description
This thesis opens with a review of classical research on academic dishonesty, peer behavior, honors code, and misinformation. Specifically, we will analyze research on peer reporting and honor codes to evaluate the efficacy of common measures taken to address academic dishonesty in higher education. This will be used as a foundation to analyze the impact that ChatGPT can have on academic dishonesty, and assess the standard measures within this emerging new context. Finally, we will suggest possible solutions to address these developments, particularly regarding the ways in which ChatGPT and other forms of AI can accelerate the spread of misinformation. The hope is to provide guidance to institutions in developing updated and effective honors codes. Crucially, any code can only be effective when faculty and staff are deeply engaged with students, and help cultivate an institutional culture of academic integrity.
ContributorsCohen, Katya (Author) / Martin, Thomas (Thesis director) / Amazeen, Polemnia (Committee member) / Barrett, The Honors College (Contributor) / School of Social Work (Contributor) / Human Systems Engineering (Contributor) / Department of Psychology (Contributor)
Created2024-05