Ph.D. - Zoology (Ecology, Evolution and Conservation Biology)
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ItemA Single Trait Drives Incipient Ecological Speciation in Sympatric Color Morphs of the Arceye Hawkfish([Honolulu] : [University of Hawaii at Manoa], [May 2016], 2016-05)Coral reef fishes represent the most diverse assemblage of vertebrates on the planet, yet our understanding of the mechanisms driving this diversity remains limited. There is growing recognition that ecological adaptation shaped by natural selection may be a major driver of diversification on coral reefs. However, few examples of ecological speciation in nature currently exist. I integrate research on ecology, behavior and genetics to outline a novel case of incipient ecological speciation in sympatric color morphs of the arceye Hawkfish (Paracirrhites arcatus). First, I demonstrate that color morphs are exploiting different niches along a steep ecological gradient, likely driven by disruptive selection favoring color patterns that are better camouflaged in contrasting microhabitats. Second, mate preference experiments show that females prefer individuals of their own morph, indicating color morphs are mating assortatively. Third, I provide genetic evidence that these premating barriers have resulted in at least partial reproductive isolation between ecologically differentiated sympatric color morphs. Taken together, these results suggest that reproductive isolation between morphs may be arising as a by-product of divergent selection on ecological differences and enhanced by the isolating effects of assortative mating. I conclude that color alone is driving incipient divergence in this species, despite high gene flow and no geographic isolation. I argue that the characteristics of this system could be quite common and thus widely applicable to thousands of reef organisms. This dissertation emphasizes the role natural selection plays in initiating speciation and should help bring us one step closer to understanding the processes driving high biodiversity in tropical seas.
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ItemInvasion Ecology and Control Feasibility of the Jackson Chameleon (Trioceros jacksonii xantholophus) in Hawai‘i([Honolulu] : [University of Hawaii at Manoa], [May 2016], 2016-05)Biological invasions provide opportunities to investigate micro-evolutionary change and the relative roles of key factors that lead to differentiation. Following introduction, release from native selective pressures and exposure to novel evolutionary forces can reduce morphological and physiological constraints and impose new ones, resulting in rapid micro-evolutionary changes. Studying ecosystem and geographic variation in invasive taxa on an ecological time scale can help provide conservation relevant information for management. I investigated ecological and evolutionary questions involving adaptation and ecomorphological variation and the roles of habitat characteristics on form, function and behavior of an invasive lizard in Hawaii. In Chapters 1 and 2 I evaluate substantial variation in head-size and horn-length among and within islands, and between native and introduced ranges. Larger heads are associated with low precipitation, and consumption and higher availability of hard prey, while longer horns are exhibited by chameleons in their native range and are associated with fight success and higher precipitation in the introduced range. Results may suggest rapid ecomorphological adaption to introduced microhabitats and release from natural selective pressures influencing sexually dimorphic characters in the native range. Chapter 3 examined predatory behavior in chameleons in response to prey size and type. Instead of the well-documented lingual prehension mechanism in Chamelaeonidae, a novel feeding mechanism is described, in association with both prey/predator size and prey type. Finally, for Chapter 4, I present the first proposed control strategy for T.j. Xantholophus in Hawaii. We tested a method based on an approach using acetaminophen deployed by resource managers to control the invasive brown tree snake on Guam. We determined minimum dosage necessary to cause >95% mortality in <48 hours. Additionally, I propose methods of field delivery, including use of introduced snail shells as a vessel for ingestion. Although there is a massive and increasing body of invasion ecology research, this study provides new insights into trait adaptation of invasive predators and how this information can help develop management strategies. In addition, this study presents a framework by which biological invasions can be used to examine evolutionary questions on an ecological rather than evolutionary time-scale.
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ItemAssessing Reproductive Biology of Hawaiian Reef Fishes: The Importance of Fisher and Community Participation([Honolulu] : [University of Hawaii at Manoa], [December 2015], 2015-12)Small-scale fisheries management is moving towards a more holistic and integrated approach, that of ecosystem–based management. This management philosophy incorporates life history, biological and physical processes, and people as integral components of the ecosystem. Although ecosystem-based management is complex, significant progress can be made by incorporating people and communities into resource monitoring and management. This research used a participatory approach and incorporated fishers and community members in research on the biology of several fish of management importance in Hawaiʻi. A fish species of ecosystem-based management importance that is often overlooked is the small pygmy goby (Eviota epiphanies). This research found that E. epiphanies exhibits fast growth and high generational turnover rates, likely contributing significantly to the bioenergetics of coral reef ecosystems. By working with fishers, reproductive biology was collected for the invasive peacock grouper (Cephalopholis argus), and the herbivorous convict tang, (Acanthurus triostegus sandvicensis). Collaborative research helped increase the number of samples collected across locations and time, improving knowledge of fish reproductive biology in Hawaiʻi across multiple scales. Findings from this research show that size at maturity and temporal shifts in spawning seasons is variable by location. These findings suggest that stewardship and management is best conducted at the local level in order to understand and respond to the variability within the ecosystem. To meet these needs, I worked with fishers, communities, NGOs, and state natural resource managers to develop community-based fishery monitoring programs to assess the reproductive biology of harvested reef fishes. These monitoring programs combined traditional Hawaiian ecological knowledge and scientific assessments to better understand local spawning seasons and optimal harvest sizes for reef fishes. By directly monitoring their resources, fishers have the information needed to track changes in their resources, and therefore the ability to respond to changing resource conditions, allowing for informed decisions on the species that are targeted and times that harvest takes place. Lastly, this research demonstrates the power of participatory approaches for collecting information need for ecosystem-based management and the social and ecological benefits of empowering fishers and communities to be monitors and stewards of their resources.
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