Unraveling the origins of social parasitism in Megalomyrmex ants

dc.contributor.advisorMueller, Ulrich G.en
dc.contributor.advisorRyan, Michael J. (Michael Joseph), 1953-en
dc.creatorAdams, Rachelle Martha Marieen
dc.description.abstractSocial parasitism, the exploitation of a society by other social organisms, has evolved independently numerous times within social animals. In this thesis, I integrate behavioral, evolutionary and chemical analyses to elucidate the evolution of social parasitism in Megalomyrmex ants. I examine host-parasite interactions in two Megalomyrmex species, identify venom alkaloids, and reconstruct the phylogenetic relationships between species. In Chapter 1, I analyze nest architecture and behavioral interactions between the ant host Cyphomyrmex cornutus and its parasite Megalomyrmex mondabora. This is the first detailed account of the natural history of this host and its social parasite. In Chapter 2, I report a one-year-long fitness experiment that tests whether Trachymyrmex cf. zeteki colonies suffer reduced fitness from an association with the social parasite Megalomyrmex symmetochus. I show that M. symmetochus parasites negatively impact host fitness though several mechanisms, including a) manipulation of the host worker grooming behavior; b) castration of host queens produced by the host colony, which then become workers; and c) reduction of garden size, host worker number, and host reproductive output. In Chapter 3, I determine that five venom alkaloids of Megalomyrmex are taxonomically informative to help differentiate cryptic species within the M. mondabora complex; new species in this complex need to be described in a future taxonomic revision. In Chapter 4, I reconstruct phylogenetic relationships of the genus Megalomyrmex with DNA sequence information. I conclude that the genus is monophyletic and corroborate two of the four species groups proposed by Brandão (1990) in a previous morphological revision. I also find evidence in support of Darwin’s Predation Hypothesis on the origin of social parasitism, which postulates that socialparasitic behaviors evolve from predatory behaviors. Lastly, I discuss promising future research directions on the evolution of social parasitism in the ant genus Megalomyrmex, which could serve as a model for the study of social parasitism in other lineages of social insects.en
dc.description.departmentEcology, Evolution and Behavioren
dc.rightsCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en
dc.subjectSocial parasitismen
dc.subjectMegalomyrmex antsen
dc.subjectHost-parasite interactionsen
dc.subjectVenom alkaloidsen
dc.subjectPhylogenetic relationshipsen
dc.subjectPredation Hypothesisen
dc.titleUnraveling the origins of social parasitism in Megalomyrmex antsen
thesis.degree.departmentEcology, Evolution and Behavioren
thesis.degree.disciplineEcology, Evolution, and Behavioren
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.nameDoctor of Philosophyen

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