This dissertation presents a political ecological case study of a Tongan village. Political ecology includes the methodological approaches of cultural ecology, concerned with understanding human/resource relations, and political economy, concerned with the historical examination of the political and social organization of production and power. The ethnography of political ecology is primarily interested in understanding how certain people use specific environmental resources in culturally prescribed and historically derive ways. With this in mind, the research provides an historical and ethnographic account of a diversified, local economic system characterized by a highly productive but depreciating smallholder agriculture once regenerative and sustainable. The smallholders in the Kingdom of Tonga are imperfectly articulated with market systems and rely on agricultural production for a significant proportion of household consumption and ceremonialized obligations to kin, and community. The dissertation presents an historical account of the political economic changes in Tonga beginning in the nineteenth century and culminating in recent alteration of traditional farming techniques and the loss of economic self-sufficiency and agricultural sustainability.

Economic valuation techniques for environmental goods and services can contribute to decisions regarding the sustainable use and preservation of natural resources. Several valuation techniques have been developed based on neoclassical economics. However, when markets fail these techniques are not applicable. An alternative approach that is less dependent on pervasive markets comes from the school of biophysical economics. This approach is based on the energy theory. According to this theory, the embodied energy of the ecosystem is estimated and a money value is assigned to it. This thesis uses a variation of a biophysical technique for the economic valuation of the above-ground biomass of a Colombian High-Andean forest. The biomass or physical organization and the diversity component of the contributory value of the forest are considered by the biomass technique. However, this technique fails to measure the ecological services component of this kind of value.

Frankliniella occidentalis response to color hue and intensity was tested in both field bioassays and electrophysiology of the thrips eye. Results of electroretinograms demonstrated that males and females have a double peak spectral efficiency in the ultraviolet near 365nm and in the green-yellow range at 540nm. Results of field tests suggest, based on density change relative to sex ratio change between behaviors, that there was a greater change in male behavior (i.e. density) than in female behavior. Higher densities of thrips were observed on blue, violet, white and yellow hues. Interactions between the UV and green photopigments and integration of visual stimuli within the central nervous system may allow for discrimination of blue and violet colors, that are at wavelengths between the two peaks. Because the peaks of spectral sensitivity and the relative efficiency are the same between sexes, and the relative rankings of density remains the same between behavior periods, the greater change in male versus female behavior may be the result of complex behavioral responses to many possible cues as yet undetermined.

I studied 1,472 locations of desert mule deer (Odocoileus hemionus crooki) (1M, 6F) before completion of the Hayden-Rhodes Aqueduct (HRA) (pre-HRA, 1981-1984), and 2,300 locations (6M, 10F) after completion of the Hayden-Rhodes Aqueduct (post-HRA, 1989-1991) to examine habitat use. I used a Geographic Information System to measure and analyze deer locations by season, sex, and year. I compared home-range size, distance to water catchments, distance to washes, vegetation use versus availability and deer interactions ≤1 km from the canal between the periods. Home-range sizes did not change significantly (P≤0.05) as a result of completion and operation of the HRA. Deer were closer to water catchments in the warmer seasons before completion of the HRA, but farther from water in the warmer seasons after completion of the HRA. Deer locations ≤1 km from the HRA increased after completion and operation of the HRA. Deer were probably relying on areas ≤1 km from the canal for forage and thermal cover.

<p> Marine resources are characteristically patchy and concealed beneath the surface of a "featureless" ocean, which makes facilitative species interactions especially advantageous to seabirds. My research addresses how behavioral mechanisms accommodate prey availability, or more specifically, how common (<i>Sterna hirundo</i>) and roseate terns (<i>S. dougallii </i>) locate and access food when it is not easily detectable. I study their foraging behavior and ecology from pre- to post-breeding, offshore in the pelagic realm (chapter 1), around the colony (chapter 2), and in nearshore waters (chapter 3). My first chapter tests the hypothesis that, as broadly-ranging seabirds, common and roseate terns forage over habitat where marine mammals and predatory fish help to find and access prey. I quantify the spatial association among foraging terns, tunas, dolphins, and their habitat, using Bayesian hierarchical models, and tests of behavioral community interactions. Facilitation explains how terns benefit from subsurface predators through local enhancement and commensal relationships: foraging tunas improve the detection and availability of prey by signaling their presence, and driving them to the surface. Chapter 2 evaluates the link between resource utilization and foraging strategy, measured by nest provisioning and patterns among foraging routes or feeding flocks. I propose that the opportunistic generalists, common terns, depend more on social cues than the specialists, roseate terns, which rely more heavily on spatial memory to find predictable prey. The results support this and suggest that increased breeding and foraging success in roseate terns relates to higher quality and abundance in their preferred prey, sandlance (<i>Ammodytes </i> spp.); in contrast, common terns seem to endure prey limitation through their use of local enhancement. In my third chapter, I hypothesize that habitat variability and prey availability predict interspecific differences in tern foraging. Behavioral tests and density-surface models, with distance sampling, show that foraging common and roseate terns respond positively to the distribution and abundance of each other and their preferred prey. Clearly, common and roseate terns use conspecifics, heterospecifics and subsurface predators to encounter prey via facilitation: such interactions create dynamic hotspots that need to be considered in an ecosystem approach to marine spatial planning.</p>

<p> This dissertation presents a case study of ecological restoration in an urban park, using a mixed-methods methodology that included a survey instrument, open-ended interviews, behavioral and trace observations, and modified grounded theory methodology for data analysis. The purpose of the study was to identify values that users of four ecologically restored areas of Chicago's Lincoln Park associated with their use of the park areas and to determine the extent to which they experienced contact with nature while visiting the areas. The study was conducted within the framework of a post-occupancy evaluation (POE) of the restoration projects, the Lincoln Park Evaluation Study in the College of Architecture, Design and the Arts, University of Illinois at Chicago, which was commissioned by the U.S. Forest Service. The author, the principal investigator for the POE, developed a set of ten values or benefits associated with park use that were included in the survey instrument and informed the onsite, open-ended interviews with park users--beauty, solitude, tranquility, recreation, health, contact with nature, habitat preservation/restoration, community identity, public life, tourism, and other (to allow respondents to add their own values to the list). The results of the study indicate that users valued contact with nature and habitat restoration most, followed closely by tranquility, solitude, and beauty, with health and recreation next and public life and community identity trailing all others. No new values were added. Data analysis suggested that respondents fell roughly into two camps, those who valued contact with nature most and those who valued habitat restoration most. Respondents who selected tranquility, solitude, or beauty as important values viewed them as secondary to contact with nature or habitat restoration because the former would be unavailable without the latter. The study's results complicates the dichotomy between natural and built environments, as respondents praised the restored areas--arguably built environments--as refuges from the city. A theme that emerged from qualitative data analysis suggests that ecological restoration of urban parks might be related to nature-identities, emotional bonds with types of natural areas, calling for future research to determine the relationship between urban nature and urban residents' nature-identities.</p>

<p>White croaker (<i>Genyonemus lineatus</i> family: Sciaenidae) are a benthic foraging fish associated with soft sediment and wastewater outfalls in Southern California. While they are used as a sentinel species due to their high organochlorine contaminant loads, little is known of their movements in relation to contaminated habitats. Acoustic telemetry was used to characterize the site fidelity, area use, and dispersal of 97 white croaker on the Palos Verdes Shelf, California. White croaker demonstrated generally low, but highly variable residency and recurrence to the Palos Verdes Shelf and exhibit nomadic movement patterns. Although the entire monitored shelf was visited by white croaker, habitats in proximity to wastewater outfalls and between 25&ndash;35 m depth were preferentially used. Approximately half of white croaker migrated into Los Angeles Harbor. These data are vital for understanding organochlorine contaminant exposure for planning future remediation and monitoring. </p>

<p> Between August 2010 and September 2012, acoustic telemetry was used to monitor movements of 31 Yellow Snapper and 25 Leopard Grouper at Los Islotes reserve, a small rocky reef and reported spawning site for both species in the southwest Gulf of California. Overall, both species exhibited site fidelity to Los Islotes (grouper: present 64 f 30% of days; snapper: 49 &plusmn; 30%). Both species frequented rock and wall habitats; though snapper showed greater site attachment to specific portions of the reserve, grouper exhibited greater site fidelity to the entire reserve. Approximately 30% of snapper showed indications of spawning-related migrations elsewhere in the Gulf, though no clear seasonal pattern of migration was found for grouper. The limited degree of spawning-related emigration and moderate-high levels of site fidelity indicate that if properly placed, small reserves such as Los Islotes may yet adequately protect small, resident populations of snapper and grouper.</p>

<p> Many organisms live in temporally or spatially heterogeneous environments. One adaptive response to environmental heterogeneity is phenotypic plasticity, or the ability of an organism to change its phenotype in response to environmental variation. Plasticity is particularly important for plants, which cannot easily escape environmental stresses (e.g., competition, herbivory, or drought), and therefore is common in many morphological and physiological traits that allow plants to cope with stresses. Despite numerous examples of the adaptive value of plasticity in plant traits, the reaction norms of many plant traits do not evolve to their predicted optima: there is often considerable genetic variation in trait plasticities, and some populations display sub-optimal responses to environmental stresses. This mismatch may reflect a balance between the fitness benefits (adaptive value) of plasticity and evolutionary constraints, such as strong genetic correlations with other traits, a lack of genetic variation in the reaction norm, and fitness costs of plasticity. </p><p> This dissertation focuses on the evolution of plasticity in plant defense responses to insect herbivores. Plant induced defenses are well-studied ecologically, but little is known about potential constraints on their evolution or the effects of these constraints on insect herbivores. Using the andromonecious herb <i>Solanum carolinense</i>, I examined the adaptive value of plasticity and tested for several evolutionary constraints on plant induced defenses and tolerance. I found damage-induced plasticity in several defense traits, and herbivores significantly reduced plant fitness in the field. However, neither tolerance nor plasticity in induced defenses was adaptive, and most traits were selected against (i.e., costly) in both environments with and without insect herbivores. </p><p> I uncovered several genetic constraints on plasticity in the plant defense response, including a) a lack of genetic variation in some resistance traits, b) strong genetic correlations between constitutive resistance and inducibility, and c) genetic correlations among the plasticities of different defense traits. Combined, these genetic constraints structured variation in the plant-mediated interaction between the specialist folivores <i>Manduca sexta</i> and <i>Leptinotarsa juncta</i>; this is the first study to demonstrate that genetic trade-offs within a plant species can affect interactions at higher trophic levels. </p><p> Although there were no fitness costs of plasticity in induced chemical/mechanical defenses, there were fitness costs of tolerance, and I was able to detect selection acting directly on trait plasticities. Selection on plasticities was generally positive or stabilizing, indicating fitness benefits of canalization of two defense traits I measured. Fitness costs of tolerance were present both in environments with and without herbivores, meaning that tolerance of herbivory was never adaptive. My dissertation is the first to simultaneously test for both the adaptive value and a breadth of evolutionary constraints (including costs of plasticity) on the plant defense response. </p><p> Combined, my results indicate that selection should reduce both the plasticity and mean expression of <i>S. carolinense</i> defenses; however, correlated selection on plastic traits or a lack of genetic variation in plasticity may prevent this from occurring. Most importantly, these results suggest that two basic predictions of evolutionary theory - that phenotypic plasticity should be both adaptive and costly - do not always hold true for plant defense traits. This underscores the importance of measuring selection on any plastic defense trait assumed to be adaptive, and investigating other potential evolutionary constraints on defensive plasticity besides fitness costs. My study shows that genetic correlations may also be important, but correlations among defense trait plasticities have been rarely investigated and most studies do not account for the presence of these correlations when examining selection on individual defense traits.</p>

<p>Amphibian populations have been declining at higher rates than bird and mammal populations. Agriculture, urbanization, including roads, and resource extraction continue to put pressure on all species. Roads in particular, are major sources of mortality. The Santa Cruz long-toed salamander (<i> Ambystoma macrodactylum croceum</i>), one of the most critically endangered species in the US, is one amphibian that is declining as a result of anthropogenic impacts, especially habitat loss and fragmentation due to urban development. Migration across roads puts these salamanders at risk from road-related death. This thesis quantified the rate of road mortality to these salamanders and other common amphibians during two A. m. croceum breeding-migration seasons in 2011&ndash;13 in a portion of the subspecies' range. Vehicular traffic was a major source of mortality to the salamander. Through traffic doubled the overall vehicle load on roads where the <i>A. m. croceum</i> migrated to and from breeding ponds. The Pacific chorus frog was also killed on the roads. This common species can be used as an indicator of road mortality risk for rarer amphibians. This study indicated that measures to reduce road mortality to the Santa Cruz long-toed salamander could include restricting vehicular traffic on roads adjacent to salamander ponds by limiting traffic to residential use only during breeding migrations, installing structures to protect <i>A. m. croceum</i> while crossing roads, and potentially assisting animals crossing roads at nighttime during the breeding migrations. </p>