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dc.contributor.advisorAviles, Leticiaen_US
dc.contributor.authorPowers, Kimberly Susan
dc.creatorPowers, Kimberly Susanen_US
dc.date.accessioned2013-04-11T09:31:33Z
dc.date.available2013-04-11T09:31:33Z
dc.date.issued2004en_US
dc.identifier.urihttp://hdl.handle.net/10150/280791
dc.description.abstractSocial spiders most likely evolved from subsocial-like ancestors, species in which siblings remain together for part of their life cycle but disperse prior to mating. Understanding the ecological conditions that favor small colony sizes and periodic dispersal in subsocial species vs. large multigenerational colonies in the social species may provide insight into this evolutionary transition. The biogeography of these spiders and the ability of prey supplementation to delay dispersal in subsocial species implicate prey abundance as an important ecological factor influencing this process. I propose a conceptual framework in which environmental prey abundance determines the rate at which prey contact webs per unit web area, colony size determines web area and prey capture success, and per capita prey capture affects when spiders disperse. To further understand how prey abundance may have influenced the evolution of sociality, I have empirically explored aspects of this framework. Within the genus Anelosimyyus, I studied two social species inhabiting an Ecuadorian lowland rain forest, a subsocial species along the edge of an Ecuadorian cloud forest, and another subsocial species occupying a temperate riparian area of Arizona. In a comparative study examining relationships among sociality, prey availability, and prey capture rate across these species, the environments of social species tended to have relatively large prey and high overall prey biomass, but not the highest numbers of prey items. Relationships among colony size, web size, and prey capture within three of these populations revealed significant foraging-related costs of increasing colony size that could be offset by the availability of high prey biomass in the form of large prey items. Finally, I conducted an experiment manipulating prey capture rate in a subsocial species that resulted in higher prey levels delaying dispersal within and among colonies. This effect often led to a single, relatively large individual remaining in nests of colonies that had been provided more prey. Overall, these findings indicate that, while the availability of high prey biomass may have allowed sociality to evolve, the concentration of prey biomass into large, but not necessarily more prey may have selected for the larger, longer-lived colonies characteristic of social species.
dc.language.isoen_USen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectBiology, Ecology.en_US
dc.subjectBiology, Zoology.en_US
dc.titlePrey abundance and the evolution of sociality in Anelosimus (Araneae, Theridiidae)en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.identifier.proquest3165789en_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineEcology & Evolutionary Biologyen_US
thesis.degree.namePh.D.en_US
dc.identifier.bibrecord.b47210126en_US
refterms.dateFOA2018-05-17T22:01:16Z
html.description.abstractSocial spiders most likely evolved from subsocial-like ancestors, species in which siblings remain together for part of their life cycle but disperse prior to mating. Understanding the ecological conditions that favor small colony sizes and periodic dispersal in subsocial species vs. large multigenerational colonies in the social species may provide insight into this evolutionary transition. The biogeography of these spiders and the ability of prey supplementation to delay dispersal in subsocial species implicate prey abundance as an important ecological factor influencing this process. I propose a conceptual framework in which environmental prey abundance determines the rate at which prey contact webs per unit web area, colony size determines web area and prey capture success, and per capita prey capture affects when spiders disperse. To further understand how prey abundance may have influenced the evolution of sociality, I have empirically explored aspects of this framework. Within the genus Anelosimyyus, I studied two social species inhabiting an Ecuadorian lowland rain forest, a subsocial species along the edge of an Ecuadorian cloud forest, and another subsocial species occupying a temperate riparian area of Arizona. In a comparative study examining relationships among sociality, prey availability, and prey capture rate across these species, the environments of social species tended to have relatively large prey and high overall prey biomass, but not the highest numbers of prey items. Relationships among colony size, web size, and prey capture within three of these populations revealed significant foraging-related costs of increasing colony size that could be offset by the availability of high prey biomass in the form of large prey items. Finally, I conducted an experiment manipulating prey capture rate in a subsocial species that resulted in higher prey levels delaying dispersal within and among colonies. This effect often led to a single, relatively large individual remaining in nests of colonies that had been provided more prey. Overall, these findings indicate that, while the availability of high prey biomass may have allowed sociality to evolve, the concentration of prey biomass into large, but not necessarily more prey may have selected for the larger, longer-lived colonies characteristic of social species.


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