Description
Gene-centric theories of evolution by natural selection have been popularized and remain generally accepted in both scientific and public paradigms. While gene-centrism is certainly parsimonious, its explanations fall short of describing two patterns of evolutionary and social phenomena: the evolution of sex and the evolution of social altruism. I review and analyze current theories on the evolution of sex. I then introduce the conflict presented to gene-centric evolution by social phenomena such as altruism and caste sterility in eusocial insects. I review gene-centric models of inclusive fitness and kin selection proposed by Hamilton and Maynard Smith. Based their assumptions, that relatedness should be equal between sterile workers and reproductives, I present several empirical examples that conflict with their models. Following that, I introduce a unique system of genetic caste determination (GCD) observed in hybrid populations of two sister-species of seed harvester ants, Pogonomyrmex rugosus and Pogonomyrmex barbatus. I review the evidence for GCD in those species, followed by a critique of the current gene-centric models used to explain it. In chapter two I present my own theoretical model that is both simple and extricable in nature to explain the origin, evolution, and maintenance of GCD in Pogonomyrmex. Furthermore, I use that model to fill in the gaps left behind by the contributing authors of the other GCD models. As both populations in my study system formed from inter-specific hybridization, I review modern discussions of heterosis (also called hybrid vigor) and use those to help explain the ecological competitiveness of GCD. I empirically address the inbreeding depression the lineages of GCD must overcome in order to remain ecologically stable, demonstrating that as a result of their unique system of caste determination, GCD lineages have elevated recombination frequencies. I summarize and conclude with an argument for why GCD evolved under selective mechanisms which cannot be considered gene-centric, providing evidence that natural selection can effectively operate on non-heritable genotypes appearing in groups and other social contexts.
Details
Title
- A practical and theoretical approach to understanding the selective mechanisms behind genetic caste determination in Pogonomyrmex rugosus and Pogonomyrmex barbatus
Contributors
- Jacobson, Neal (Author)
- Gadau, Juergen (Thesis advisor)
- Laubichler, Manfred (Committee member)
- Pratt, Stephen (Committee member)
- Arizona State University (Publisher)
Date Created
The date the item was original created (prior to any relationship with the ASU Digital Repositories.)
2012
Subjects
- Biology
- Evolution & development
- Genetics
- Dependent Lineage
- Genetic Caste Determination
- Model
- Natural selection
- Pogonomyrmex barbatus
- Pogonomyrmex rugosus
- Rough harvester ant--Genetics.
- Rough harvester ant
- Rough harvester ant--Evolution.
- Rough harvester ant
- Rough harvester ant--Behavior.
- Rough harvester ant
Resource Type
Collections this item is in
Note
- thesisPartial requirement for: M.S., Arizona State University, 2012
- bibliographyIncludes bibliographical references (p. 94-100)
- Field of study: Biology
Citation and reuse
Statement of Responsibility
by Neal Jacobson