Matching Items (13)
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The coordination of group behavior in the social insects is representative of a broader phenomenon in nature, emergent biological complexity. In such systems, it is believed that large-scale patterns result from the interaction of relatively simple subunits. This dissertation involved the study of one such system: the social foraging of

The coordination of group behavior in the social insects is representative of a broader phenomenon in nature, emergent biological complexity. In such systems, it is believed that large-scale patterns result from the interaction of relatively simple subunits. This dissertation involved the study of one such system: the social foraging of the ant Temnothorax rugatulus. Physically tiny with small population sizes, these cavity-dwelling ants provide a good model system to explore the mechanisms and ultimate origins of collective behavior in insect societies. My studies showed that colonies robustly exploit sugar water. Given a choice between feeders unequal in quality, colonies allocate more foragers to the better feeder. If the feeders change in quality, colonies are able to reallocate their foragers to the new location of the better feeder. These qualities of flexibility and allocation could be explained by the nature of positive feedback (tandem run recruitment) that these ants use. By observing foraging colonies with paint-marked ants, I was able to determine the `rules' that individuals follow: foragers recruit more and give up less when they find a better food source. By altering the nutritional condition of colonies, I found that these rules are flexible - attuned to the colony state. In starved colonies, individual ants are more likely to explore and recruit to food sources than in well-fed colonies. Similar to honeybees, Temmnothorax foragers appear to modulate their exploitation and recruitment behavior in response to environmental and social cues. Finally, I explored the influence of ecology (resource distribution) on the foraging success of colonies. Larger colonies showed increased consistency and a greater rate of harvest than smaller colonies, but this advantage was mediated by the distribution of resources. While patchy or rare food sources exaggerated the relative success of large colonies, regularly (or easily found) distributions leveled the playing field for smaller colonies. Social foraging in ant societies can best be understood when we view the colony as a single organism and the phenotype - group size, communication, and individual behavior - as integrated components of a homeostatic unit.
ContributorsShaffer, Zachary (Author) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Janssen, Marco (Committee member) / Fewell, Jennifer (Committee member) / Liebig, Juergen (Committee member) / Arizona State University (Publisher)
Created2014
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Description
Division of labor among task specialists is a key feature of the organization of insect societies. Foraging and emigration are two distinct colony tasks that nonetheless depend on very similar behaviors, including searching outside the nest, evaluating discoveries, and recruiting nestmates. These subtasks are crucial to collective decisions about forager

Division of labor among task specialists is a key feature of the organization of insect societies. Foraging and emigration are two distinct colony tasks that nonetheless depend on very similar behaviors, including searching outside the nest, evaluating discoveries, and recruiting nestmates. These subtasks are crucial to collective decisions about forager allocation and nest site selection. It remains unclear, however, whether the same ants are responsible for similar behavior in both contexts, and to what degree they show finer specializations among common subtasks. We are investigating these issues in the ant Temnothorax rugatulus, by making detailed behavioral descriptions of individually marked colonies as they forage and emigrate. There exists considerable heterogeneity among nest-movers, with a small proportion consistently responsible for a large share of recruitment. We found a similar pattern of heterogeneity amongst ants retrieving food during foraging, but had inconclusive results when examining recruitment to the food. It also appears that the ants that complete tasks during foraging are different from the ants that complete similar tasks during emigrations. These findings will shed light on the organization of division of labor and how it contributes to collective decision-making.
ContributorsSchaper, Gage (Contributor) / Pratt, Stephen (Thesis director) / Fewell, Jennifer (Committee member) / Shaffer, Zachary (Committee member) / Barrett, The Honors College (Contributor)
Created2013-05
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Description
Temnothorax ants are a model species for studying collective decision-making. When presented with multiple nest sites, they are able to collectively select the best one and move the colony there. When a scout encounters a nest site, she will spend some time exploring it. In theory she should explore the

Temnothorax ants are a model species for studying collective decision-making. When presented with multiple nest sites, they are able to collectively select the best one and move the colony there. When a scout encounters a nest site, she will spend some time exploring it. In theory she should explore the site for long enough to determine both its quality and an estimate of the number of ants there. This ensures that she selects a good nest site and that there are enough scouts who know about the new nest site to aid her in relocating the colony. It also helps to ensure that the colony reaches a consensus rather than dividing between nest sites. When a nest site reaches a certain threshold of ants, a quorum has been reached and the colony is committed to that nest site. If a scout visits a good nest site where a quorum has not been reached, she will lead a tandem run to bring another scout there so that they can learn the way and later aid in recruitment. At a site where a quorum has been reached, scouts will instead perform transports to carry ants and brood there from the old nest. One piece that is missing in all of this is the mechanism. How is a quorum sensed? One hypothesis is that the encounter rate (average number of encounters with nest mates per second) that an ant experiences at a nest site allows her to estimate the population at that site and determine whether a quorum has been reached. In this study, encounter rate and entrance time were both shown to play a role in whether an ant decided to lead a tandem run or perform a transport. Encounter rate was shown to have a significant impact on how much time an ant spent at a nest site before making her decision, and encounter rates significantly increased as migrations progressed. It was also shown to individual ants did not differ from each other in their encounter rates, visit lengths, or entrance times preceding their first transports or tandem runs, studied across four different migrations. Ants were found to spend longer on certain types of encounters, but excluding certain types of encounters from the encounter rate was not found to change the correlations that were observed. It was also found that as the colony performed more migrations, it became significantly faster at moving to the new nest.
ContributorsJohnson, Christal Marie (Author) / Pratt, Stephen (Thesis director) / Pavlic, Theodore (Committee member) / Shaffer, Zachary (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2013-05
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Description
In large part, the great success of eusocial insects is due to efficient division of labor (Duarte et al. 2011; Dornhaus 2008). Within ant colonies, the process of dividing labor is not clearly defined, but it may be key to understanding the productivity and success of these colonies. This study

In large part, the great success of eusocial insects is due to efficient division of labor (Duarte et al. 2011; Dornhaus 2008). Within ant colonies, the process of dividing labor is not clearly defined, but it may be key to understanding the productivity and success of these colonies. This study analyzed data from an experiment that was conducted with the goal of examining how finely division of labor is organized in ant colonies. The experiment considered the actions of all ants from three Temnothorax rugatulus colonies. The colonies were each carefully recorded during five distinct emigrations per colony. The experiment produced such a large quantity of data that it was challenging to analyze the results, a major obstacle for many studies of collective behavior. Therefore, I designed a computer program that successfully sorted all of the data and prepared it for an initial statistical analysis that was performed in R. The preliminary results suggest that while most of the ants perform little to no work, there is an overall pattern of elitism; it seems that division of labor in ants is not more finely divided than previously shown. Future studies should provide further analysis of the data and will be useful in forming a more complete understanding of the division of labor within the emigrations of Temnothorax rugatulus colonies.
ContributorsJones, Samantha (Author) / Pratt, Stephen (Thesis director) / Jones, Donald (Committee member) / Shaffer, Zachary (Committee member) / Barrett, The Honors College (Contributor) / W. P. Carey School of Business (Contributor)
Created2012-12
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The evolution of cooperation is a fundamental problem in biology, especially for non-relatives, where indirect fitness benefits cannot counter within-group inequalities. Multilevel selection models show how cooperation can evolve if it generates a group-level advantage, even when cooperators are disadvantaged within their group. This allows the possibility of group selection,

The evolution of cooperation is a fundamental problem in biology, especially for non-relatives, where indirect fitness benefits cannot counter within-group inequalities. Multilevel selection models show how cooperation can evolve if it generates a group-level advantage, even when cooperators are disadvantaged within their group. This allows the possibility of group selection, but few examples have been described in nature. Here we show that group selection can explain the evolution of cooperative nest founding in the harvester ant Pogonomyrmex californicus. Through most of this species’ range, colonies are founded by single queens, but in some populations nests are instead founded by cooperative groups of unrelated queens. In mixed groups of cooperative and single-founding queens, we found that aggressive individuals had a survival advantage within their nest, but foundress groups with such non-cooperators died out more often than those with only cooperative members. An agent-based model shows that the between-group advantage of the cooperative phenotype drives it to fixation, despite its within-group disadvantage, but only when population density is high enough to make between-group competition intense. Field data show higher nest density in a population where cooperative founding is common, consistent with greater density driving the evolution of cooperative foundation through group selection.

ContributorsShaffer, Zachary (Author) / Sasaki, Takao (Author) / Haney, Brian (Author) / Janssen, Marco (Author) / Pratt, Stephen (Author) / Fewell, Jennifer (Author) / College of Liberal Arts and Sciences (Contributor)
Created2016-07-28
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In this quantitative research paper, we explored the correlation between the six dimensions of motivation as part of the Self-Determination Theory spectrum and physical activity. In addition, our aim was to also see if Transcranial Direct Current Stimulation (tDCS) paired with exercise as an intervention would affect motivation to exercise

In this quantitative research paper, we explored the correlation between the six dimensions of motivation as part of the Self-Determination Theory spectrum and physical activity. In addition, our aim was to also see if Transcranial Direct Current Stimulation (tDCS) paired with exercise as an intervention would affect motivation to exercise over time.

ContributorsPankoff, Mia (Author) / Quezada, Gabrielle (Co-author) / Katsanos, Christos (Thesis director) / Shaffer, Zachary (Committee member) / Ruiz Tejada, Anaissa (Committee member) / Barrett, The Honors College (Contributor) / Edson College of Nursing and Health Innovation (Contributor)
Created2021-12
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Description

In this quantitative research paper, we explored the correlation between the six dimensions of motivation as part of the Self-Determination Theory spectrum and physical activity. In addition, our aim was to also see if Transcranial Direct Current Stimulation (tDCS) paired with exercise as an intervention would affect motivation to exercise

In this quantitative research paper, we explored the correlation between the six dimensions of motivation as part of the Self-Determination Theory spectrum and physical activity. In addition, our aim was to also see if Transcranial Direct Current Stimulation (tDCS) paired with exercise as an intervention would affect motivation to exercise over time.

ContributorsQuezada, Gabrielle (Author) / Pankoff, Mia (Co-author) / Katsanos, Christos (Thesis director) / Shaffer, Zachary (Committee member) / Ruiz Tejada, Anaissa (Committee member) / Barrett, The Honors College (Contributor) / Edson College of Nursing and Health Innovation (Contributor) / College of Integrative Sciences and Arts (Contributor)
Created2021-12
Description

Oxymonas is a genus of Oxymonad protist found in the hindgut of drywood termites (family Kalotermitidae). Many genera of drywood termites are invasive pests globally. The hindgut microbiome of Cryptotermes brevis, the West Indian drywood termite, has not been described in detail, and only one published sequence exists of Oxymonas

Oxymonas is a genus of Oxymonad protist found in the hindgut of drywood termites (family Kalotermitidae). Many genera of drywood termites are invasive pests globally. The hindgut microbiome of Cryptotermes brevis, the West Indian drywood termite, has not been described in detail, and only one published sequence exists of Oxymonas from C. brevis. This study aims to analyze Oxymonas sequences in C. brevis from whole gut genetic material, as well as to dissect its place in phylogenetic trees of Oxymonas and how it fits into specific and evolutionary patterns. To amplify the 18S rRNA gene Oxymonas from C. brevis, the MasterPure DNA extraction kit was used, followed by PCR amplification, followed by agarose gel electrophoresis, followed by purification of the resulting gel bands, followed by ligation/transformation on to an LB agar plate, followed by cloning the resulting bacterial colonies, and topped off by colony screening. The colony screening PCR products were then sequenced in the Genomics Core, assembled in Geneious, aligned and trimmed into a phylogenetic tree, along with several long-read amplicon sequences from Oxymonas in other drywood termites. All whole gut sequences and one amplicon from C. brevis formed a single clade, sharing an ancestor with a sister clade of Oxymonas sp. from C. cavifrons and Procryptotermes leewardensis, but the other long-read fell into its own clade in a different spot on the tree. It can be conjectured that the latter sequence was contaminated and that the C. brevis clones are a monophyletic group, a notion further corroborated by a distantly related clade featuring sequences from Cryptotermes dudleyi, which in turn has a sister taxon of Oxymonas clones from C. cavifrons and P. leewardensis, pointing toward a different kind of co-diversification of the hosts and symbionts rather than cospeciation.

ContributorsSharma, Noah (Author) / Gile, Gillian (Thesis director) / Shaffer, Zachary (Committee member) / Coots, Nicole (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2023-05
Description

Although social hierarchies are commonly found all throughout nature, the underlying mechanisms of their formation are still ambiguous. Hierarchies form through a wide range of interactions between subordinate and dominant individuals, and the ponerine ant Harpegnathos saltator provides the perfect model to explore such dominance behaviors. When the queen is

Although social hierarchies are commonly found all throughout nature, the underlying mechanisms of their formation are still ambiguous. Hierarchies form through a wide range of interactions between subordinate and dominant individuals, and the ponerine ant Harpegnathos saltator provides the perfect model to explore such dominance behaviors. When the queen is absent or her fecundity levels drop below a certain threshold, H. saltator workers undergo a dominance tournament, in which several individuals emerge as gamergates, reproductive workers that are not queens. During this tournament, several characterizable dominance behaviors are exhibited (antennal dueling, dominance biting, and policing), which can be used to study the behavioral and social dynamics in the formation of a reproductive hierarchy. Colonies of 15, 30, 60, and 120 workers were created in duplicate, and their dominance tournaments were recorded to study how these interactions impact gamergate establishment. Rather than studying these behaviors as isolated incidents, responses to policing behaviors (timid, neutral, or aggressive) and their duration were recorded along with the frequency of dueling. Three groups were determined: dueling future gamergates (DFG), dueling future non-gamergates (DFNG) and non-dueling individuals (ND). DFNG received many more policing attacks and the duration of these interactions lasted much longer. DFG consistently exhibited the most dueling. Timid and neutral responses were more common than aggressive responses, perhaps due to energy conversation purposes. Peaks in dueling correspond to peaks in policing, highlighting the dynamic behavioral interactions necessary for the formation of a reproductive hierarchy.

ContributorsOlivas, Victoria (Author) / Liebig, Juergen (Thesis director) / Shaffer, Zachary (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor) / School of International Letters and Cultures (Contributor)
Created2023-05
Description

Black-footed ferrets have become one of the most popular conservation success stories because of the miraculous rediscovery of the species after being declared extinct and the growing population today. The stability of the species is still highly variable as the ferrets are threatened by disease, habitat fragmentation, human infringement, and

Black-footed ferrets have become one of the most popular conservation success stories because of the miraculous rediscovery of the species after being declared extinct and the growing population today. The stability of the species is still highly variable as the ferrets are threatened by disease, habitat fragmentation, human infringement, and the extermination of their main prey item the prairie dog. The complexity of the issue arises from negative public perceptions of prairie dogs leading to less citizen support for protection which in turn undermines progress in black-footed ferret conservation. General issues with the bureaucracy of conservation helps to delay a formal protection of species at risk which would be especially important for species that are actively being removed or exterminated by humans like the prairie dog. Careful analysis of the black-footed ferret and the prairie dog through the lenses of their natural histories, conservation histories, and modern conservation methods suggest that the public’s opinion and support is the greatest tool for the protection of species at risk because of the complexity of conservation and the rallying bureaucratic motion.

ContributorsMarek, Aislinn (Author) / Taylor, Jesse (Thesis director) / Shaffer, Zachary (Committee member) / Barrett, The Honors College (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / School of Life Sciences (Contributor)
Created2023-05