• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    How Does Diversity Influence System Performance? The Evolutionary Ecology of Body Size Variation in the Common Eastern Bumble Bee (Bombus impatiens)

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_17290_sip1_m.pdf
    Size:
    3.535Mb
    Format:
    PDF
    Download
    Author
    Kelemen, Evan Patrick
    Issue Date
    2019
    Keywords
    Bombus
    complex systems
    social insects
    variation
    Advisor
    Dornhaus, Anna
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    Variation among the components within complex systems exists at all levels throughout biology from molecular networks to ecosystems, and the behavior of these complex systems arises from the actions and interactions of their components. Despite the prevalence of differences among components in such systems, the trait variation displayed by the components in these systems is frequently ignored or assumed beneficial to the system. However, there are situations in which component variation can be costly to a system, especially when the composition of components exist that do not match the task demands on a system. Therefore, we examine here the relationship of component variation to system performance, and why? This dissertation seeks to understand the underlying mechanisms that can generate variation within a system, as well as the conditions under which this variation is expected to evolve. I tested these questions in bumble bees (Bombus spp.), which are a useful system because they exhibit a great variation in body size among workers within the colony, and component variation can be experimentally manipulated (i.e., different-sized workers can be removed) to determine the effects of component diversity on system performance. In my first chapter, I find that size variation within bumble bee (Bombus impatiens) colonies is a plastic trait that responds to environmental conditions. While size variation increases with environmental temperature, temperature itself is not the mechanism that generates size variation, and workers maintain the developing workers (i.e. brood) at a uniform temperature. The production of variation in worker size could be adaptive, however, my results do not exclude the possibility that size variation is a result of an inability of the colony to produce more uniform body sizes. In chapter two, I find that size variation within a colony is not the result of an inability of the colony to control size during development, as not all groups of individuals produced by the colony display such a large size variation as the worker caste. Males and queens raised together with workers display greatly reduced size variation. Additionally, the size variation exhibited by colonies is the lab is not greater than that found in wild colonies. These results suggest that size variation is not a lab artifact and may be common across environments, and that colonies can control the amount of diversity produced. Therefore, is there a benefit to the colony to producing variably sized workers? In chapter three, I find that colonies with greater size variation do not produce more brood under either constant or variable access to food compared to similarly sized colonies with less worker size variation. These results suggest that the commonly assumed hypothesis that variation increases system efficiency (i.e. colonies to produce more individuals) and system robustness (i.e. colonies to survive environmental perturbations) may not explain body size variation within bumble bees, or at least that they do not do so under lab conditions. In chapter four, I combine economic theory and empirically-measured phenotypic-specific costs to propose a novel hypothesis, that diversity may have evolved as a way to increase group efficiency by minimizing opportunity costs to the group through the production of phenotypes that have a comparative advantage at different tasks. The model that I built and parametrized from the bumble bee literature suggests that colony efficiency increases with size variation. The model results differ from the empirical results, suggesting that the benefits of comparative advantage may only be apparent in colonies that forage in a more demanding natural environment. This body of work thereby suggests that some of the common assumptions about the function of component variation, e.g. that each component type is uniquely suited to one task, do not always explain and why it exists. I propose here a new hypothesis for why variation may evolve: components may vary in cost-benefit tradeoff differentially across tasks. This novel hypothesis argues for the importance of considering the production costs of the different components within the system relative to their performances. This hypothesis may also reconcile the mixed results from previous studies on the relationship between component variation and system performance.
    Type
    text
    Electronic Dissertation
    Degree Name
    Ph.D.
    Degree Level
    doctoral
    Degree Program
    Graduate College
    Ecology & Evolutionary Biology
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.