Model organisms are useful tools for investigating generalities in biology and have greatly advanced current understanding of adaptive behavior. Yet Krogh's principle⁰́₄that there exists specialized species most convenient for answering specific biological questions⁰́₄suggests that non-model organisms may be best suited for identifying specific genetic and physiological underpinnings of behavior. In fact, non-model organisms with unique traits have been instrumental for examining the potential selective pressures and underlying genetic mechanisms of adaptive behavior. I present two groups of vertebrates, desert rodents and Osteoglossiformes fishes, as exemplary non-model organisms that support Krogh's principle and are particularly appropriate for the integrative study of predatory and reproductive behaviors, respectively. I first compare the history, benefits, and limitations of standard laboratory and nontraditional model species before describing the particular biological traits that make desert rodents and osteoglossiforms poised to be useful nontraditional model organisms. In Chapter 1, I analyze the predatory behavior of desert rodents and find that carnivorous grasshopper mice (Onychomys torridus) are the most persistent and efficient rodent predators of chemically defended beetles and undefended crickets. Their success is due to their attack behavior, even though they are exposed to the beetles' benzoquinone spray. These results suggest that grasshopper mice's predatory behavior enables them to potentially outcompete related rodents and occupy an obligately carnivorous dietary niche in the desert. In Chapter 2, I demonstrate that grasshopper mice are equally gustatorily sensitive and averse to benzoquinone as laboratory house mice (Mus musculus), but they also contain mutations in a sensory channel known to be activated by benzoquinone. Grasshopper mice and their relatives may therefore be informative models for exploring chemosensory mechanisms and optimal foraging theory. In Chapter 3, I review the diverse reproductive anatomy, morphology, and behavior of Osteoglossiformes fishes, and the role of sperm competition and sexual selection in shaping their reproductive adaptations. This review highlights the ways in which osteoglossiforms can be used as models for understanding reproductive diversity among teleost fish, as well as the evolution of body plan development, fertilization strategies, and parental care. I conclude with a discussion about how the results from this work provide new species-specific information and exemplify the ways in which these systems can be used within a comparative framework to contribute to biomedicine, conservation, and other broader biological topics. Advancements in the ability to link genes to behavior suggest that focusing on more diverse nontraditional model systems is an increasingly feasible way to expand comprehensive knowledge of adaptive behavior. This dissertation proposes that embracing exemplary species, such as grasshopper mice and Osteoglossiformes, is the next step for developing new investigations inspired from work using model species, and for capturing the complexity of natural variation within experimental research.
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