Dissertation
Evolution of Larval Growth Curves in Tribolium castaneum: Analyzing Constraints in a Function-Valued Trait Framework
Doctor of Philosophy (PhD), Washington State University
01/2014
Handle:
https://hdl.handle.net/2376/108137
Abstract
Body size often impacts individual fitness. Since final body size is attained through a process of growth, it is likely that growth patterns also have fitness consequences. Previous studies have found high levels of standing additive genetic (co)variance for growth trajectories despite the expectation that additive variance should be depleted by frequent, strong directional selection. Because growth trajectories are continuous by nature they are amenable to analysis using a function-valued (FV) trait framework to reveal their underlying genetic architecture. The FV framework was implemented to estimate the additive genetic covariance function for growth curves in Tribolium castaneum, and revealed that additive genetic variance is indeed plentiful and that evolution is probably limited through evolutionary constraints of a different type. Artificial selection can be used to demonstrate some of these alternate types of constraints. Though previous experiments have artificially selected on size at one or a few landmark ages, a novel FV method was designed to artificially select the growth curves through their continuous length to test for genetic constraints. Results indicated a significant response after one generation of selection, but no response afterwards. Correlated responses included increased mortality, increased critical weight, and decreased development time (DT). To further investigate the constraints that may be caused by these genetically correlated traits, a novel model was developed and used to estimate the additive genetic covariance between FV traits and landmark, singly-measured traits (such as DT). These novel additive covariance estimates can be used to predict evolutionary responses to natural or artificial selection in both the FVT and the landmark trait. Estimates of the additive covariance between growth curves and three DT traits indicate that body size and DT do not necessarily covary in the same direction throughout the growth period; predictions made using these estimates suggest that these covariances limit the evolutionary response of all traits analyzed, but to a lower degree than anticipated. In conclusion, the evolution of larval growth curves is likely constrained by their genetic covariances with not only a few but with many correlated traits.
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Details
- Title
- Evolution of Larval Growth Curves in Tribolium castaneum: Analyzing Constraints in a Function-Valued Trait Framework
- Creators
- Kristen Irwin
- Contributors
- Patrick A Carter (Advisor)Marc A Evans (Committee Member)Richard N Gomulkiewicz (Committee Member)Nancy E Heckman (Committee Member)Laura C Lavine (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 135
- Identifiers
- 99900581845601842
- Language
- English
- Resource Type
- Dissertation