The greenside darter, Etheostoma blennioides (Teleostomi: Percidae), is a wide-ranging polytypic taxon that occurs throughout Eastern North America. A prior morphological study recognized that E. blennioides was comprised of four subspecies, several morphological races, and three zones of morphological intergradation. This dissertation uses complete sequences from the mitochondrial cytochrome b gene to estimate phylogenetic relationships for 28 populations within the complex. The results from this portion of the dissertation suggest that taxonomic rearrangement is needed, as the currently recognized taxa do not conform to distinct evolutionary lineages. The taxa in the E. blennioides occupy distinctive habitats, including large rivers, upland streams, and shorelines of the Great Lakes. Ecological (microhabitat) and morphological (fin size) data were gathered from 19 populations of greenside darters from across the range of the complex. One of the four equally parsimonious phylogenies generated in Chapter II was used to examine the relationship between ecology and morphology in a phylogenetic context. Fin sizes, morphological characters considered most sensitive to environmental conditions in these fishes, were utilized in a phylogenetic comparative analysis (spatial autocorrelation). The results indicated that no significant phylogenetic constraint exists for fins. Results from a canonical correlation analysis indicated that there was a significant relationship between microhabitat and morphological phenotype for females, but not for males. Factors associated with morphological and ecological diversification of the complex are discussed. Finally, a previous study of geographic variation of the E. blennioides complex failed to address differences in body shape. Therefore, modern geometric morphometric techniques were applied to examine differences in body shape across the range of E. blennioides . Based on landmark-based methods of analysis, the results indicate that there are significant differences in body shape among the taxa in the complex. These shape differences further strengthen the conclusion of species recognition for the genetically unique taxa identified in Chapter II / acase@tulane.edu

Empirical studies in Ecology have shown that insect herbivores feeding on plants with high concentrations of secondary metabolites are more likely to be successfully parasitized. This dissertation research examined one potential mechanism by which plant secondary metabolites render herbivores vulnerable to attack by natural enemies: secondary metabolites may have a negative effect on the physiology and immune response of lepidopteran larvae (caterpillars). An experimental approach tested the novel hypothesis that herbivores feeding on plants with high concentrations of iridoid glycosides and amides/imides are more likely to be successfully parasitized because of a weakened immune response In controlled experiments when the specialist nymphalid caterpillar, Junonia coenia, sequestered high levels of iridoid glycosides it was immunocompromised compared to caterpillars sequestering at low concentrations. The immune response of the generalist arctiid caterpillar, Grammia incorrupta, was not affected by feeding on diets with high concentrations of iridoid glycosides. The effects of imides/amides on caterpillar immune responses were also tested using specialist geometrid caterpillars, Eois spp., and the generalist noctuid caterpillar, Spodoptera exigua. There was no significant effect of the imides/amides on the immune response of any of these caterpillars. Lastly, the immune response was measured across 15 species of caterpillars from 10 different families. Caterpillars with a strong immune response were less likely to be parasitized. When compared to other defenses against parasitoids, the defensive value of the immune response against parasitoids is at least an order of magnitude greater than behavioral or morphological defenses Together, these results show that both plant chemistry and natural enemies play an influential part in determining diet breadth of caterpillars. Many ecological studies have shown that caterpillars that specialize on specific host plants and evolve to sequester the host plant secondary metabolites are protected from predators due to their acquired toxicity. However, the data from this dissertation research show that this is not always the case, and that caterpillars sequestering in high concentrations are immunocompromised and may be susceptible to greater parasitism. The current paradigm of how plant-caterpillar-predator interactions are structured should take into account more specialized interactions like those shown in this dissertation / acase@tulane.edu

This study focuses on the endocrine-disrupting capabilities of paper and pulpmill effluents discharged into Elevenmile Creek, FL; specifically effects of effluents on levels of testosterone, 11-ketotestosterone, estradiol in blood, vitellogenin production, gonadosomatic index, and condition coefficients in bluegill sunfish, Lepomis macrochirus. Bluegill were captured monthly for one year from Elevenmile Creek and a reference site---Blackwater River. Standard length and weight were recorded, and blood samples were collected. All hormone and vitellogenin levels were measured by ELISA. The reproductive cycle of bluegill in the southeastern United States in a blackwater system was also determined from reference site data. The livers of formalin fixed specimens archived in Tulane's Museum of Natural History from Elevenmile Creek and from the reference site were immunohistochemically examined in an attempt to detect historical differences in vitellogenin production between fish from the two sites. The alternate hypothesis of this investigation was that female bluegill would exhibit a type of masculinization as seen in female mosquitofish captured from this site, indicating an androgenic effect of this type of contamination. Results of Chapter II show that, when compared to reference females, females from Elevenmile Creek exhibited significantly higher levels of estradiol in Spring 2001 (5.50 ng/ml vs. 2.30 ng/ml), vitellogenin in Winter 2001 (2833.70 mug/ml vs. 187.96 mug/ml). When compared to reference males, males from Elevenmile Creek exhibit higher levels of estradiol in Summer 2001 (5.96 ng/ml vs. 2.27 ng/ml), and vitellogenin in Fall 2600 (1136.20 mug/ml vs. 86.57 mug/ml). There was no evidence of masculinization of females or supermasculinization of males. The added nutrients, food supply, and species differences are all plausible explanations for the increased levels of hormones and vitellogenin in bluegill from Elevenmile Creek The reproductive cycle of bluegill found in Florida in blackwater system, displayed in Chapter II begins in spring (April) and continues through the summer (September). In Chapter III, vitellogenin was detected in formalin fixed livers. Historical evidence also shows that exposure of paper and pulpmill effluents has had no adverse effects on the reproductive physiology of bluegill sunfish in the past / acase@tulane.edu

In this dissertation, I address the distribution and conservation of the Amazonian avifauna at several different scales. In Chapter 1, I looked at how the spatial bias in ornithological collections affects our understanding of the patterns of diversity in Amazonia. I showed that Amazonia is massively under-collected, that biological collection sites cluster around points of access, and that the richness at collection localities is higher than would be expected at random. This greater richness in collected areas was associated with a higher proportion of species with small geographical ranges as compared to uncollected areas. These small range species are relevant for conservation, as they are especially prone to extinction. I concluded that the richness of the uncollected areas of Amazonia is seriously underestimated, and that current knowledge gaps preclude accurate selection of areas for conservation in Amazonia. With this in mind, I modeled the impacts of continued deforestation on the Amazonian endemic avifauna. To overcome knowledge gaps, I complemented bird range maps with a "bird-ecoregions." I identified several taxa and bird-ecoregions likely to face great threat in the near future, most of them associated with riverine habitats. To evaluate these predictions, I conducted a detailed study on two riverine species: the Rio Branco Antbird (Cercomacra carbonaria) and the Hoary-throated Spinetail (Synallaxis kollari). Both are threatened and endemic to the gallery forests of Roraima, Brazil. I predicted that both would lose critical habitat in the near future. I concluded that neither is categorized correctly in by The World Conservation Union and recommend the down-listing of the Rio-Branco-Antbird and the up-listing of the Hoary-throated Spinetail. I also explored the importance of indigenous reserves for the conservation of both species and emphasized the need for greater involvement of conservation biologists in the social issues related to their study organisms. / Dissertation

<p>Coral reef fish coexist in a state of high diversity that has not been successfully explained by niche diversification, larval supply, differential mortality, or a suite of other proposed factors. These processes are all occurring on a diverse substrate that would be expected to affect the abundance and distribution of fish by directing habitat preferences as well as affecting competitive and predatory success. I conducted correlational studies on healthy and degraded Caribbean reefs that addressed fish abundances at the levels of community, species, and age class. I also experimentally tested habitat preferences in two ways: choice experiments on adults of common species that determined preferences for live coral and rugosity in an isolated environment, and monitoring of artificial reefs differing in live coral cover that tested habitat selection of adults and juveniles in the field. These observations all show that live coral had no effect on community parameters such as abundance or diversity, but that rugosity was positively related to species richness. However, these measures of the community masked differences at the species and age class level. A handful of species exhibited positive or negative preferences for live coral, but these selections did not follow a taxonomic or trophic-level classification. Species within the genus Stegastes, for example, could either aggregate towards or avoid live coral. One species even reversed its habitat preference as it matured. Field distributions were not determined solely by these habitat preferences, but inclusion of competitive interactions into a multi-factorial model explained distribution of some species. Results suggest that changes in live coral cover, an increasingly common phenomenon, would not affect fish at a community level, but could affect a few species through changes to recruitment or alteration of competitive interactions.</p> / Dissertation

<p>Increased pressure has been placed on researchers to focus on processes at an ecosystem level. However, ecological processes operate at multiple scales from an individual predator up to ocean basin migrations, and research across these scales is extremely difficult. More accurate and detailed understanding of prey distributions relative to physical and biological features can greatly aid in understanding top predator distributions and ultimately ecosystem functioning. High resolution acoustic data is a critical tool that can be used to investigate food web linkages at many spatial scales. At a broad scale, migratory top predators are often modeled relative to oceanographic structure as a proxy for the distribution of their prey. At a fine scale, combining novel technologies including fisheries acoustics, real time oceanographic sensors, and digital tags allows examination of decisions made by an individual foraging whale. In the Gulf of Mexico, fish distributions at fine scales (both horizontal and vertical) were examined relative to hypoxic bottom waters to understand potential ecosystem effects. Forage fish distribution (sand lance, Ammodytes spp.) were measured relative to physical features and oceanographic processes up to the decision making of a top predator, the humpback whale (Megaptera novaeangliae). The effect of geostrophic currents and environmental regimes on the deep scattering layers of the central tropical pacific were examined relative to sightings of marine mammals in the area. Analyses across trophic levels and at multiple scales is an important step towards understanding community ecology and ecosystem processes in pelagic systems.</p> / Dissertation

The impacts of El Nino Southern Oscillation (ENSO) on precipitation, reference evapotranspiration, and vegetation in a three-state region of central Mexico were investigated using daily weather data from 20 weather stations for the years 1970 through 1990, which included 5 El Nino years, 5 La Nina years, and 11 Neutral years. In addition, two years, 1997 (El Nino), and 1998 (La Nina) of 10-day NDVI composites were analyzed during the growing season (May-Oct) along with precipitation and reference evapotranspiration (ETo) over central Mexico. Regional precipitation trends were analyzed using the normalized rainfall departures. The interannual variation of vegetation cover was analyzed using the NDVI on 10-day and monthly bases. The Food and Agricultural Organization (FAO) Penman-Monteith method was used to calculate ETo. The dynamics of the soil water balance in central Mexico was evaluated according to the method proposed by Thornthwaite and Mather. Analyses indicate that driest conditions occurred within the northern part of the region and during neutral ENSO years. Rainfall amounts during El Nino and Neutral years were not statistically different however, La Nina years were about 30% wetter than N and EN years (0.05 level). The correlation coefficient between NDVI and precipitation was 0.79 in 1997, and 0.52 in 1998, in June and July, respectively. Negative correlation was found between NDVI and reference evapotranspiration during the rainy months of July and August. The spatio-temporal variability of NDVI showed that there was significant statistical difference in NDVI between regions, but not between years. Regional soil water balance determinations indicated that conditions were most favorable in the Southern part of the region for crop growth during La Nina years. In general, soil water deficits were reduced by about 50% during the growing season compared to the annual soil water deficits.

Computer models used to predict the pattern and rate of spread of fire in grasslands as well as other vegetation types rely on various inputs for their calculations. Because of the direct effect they have on the quantity of fuel available to carry a fire and the effects of moisture on the potential for fuel available to carry a fire and the effects of moisture on the potential for fuel to begin burning and to sustain a fire, fuel loading measurements, which are similar to production measurements in grasslands, and estimates of fuel moisture are two important variables to be considered when modeling fire behavior. The objective of this project is to determine if there is a relationship between measured environmental variables and the fuel moisture values at the same sample points which can be modeled with GIS data and neural networks. This study was carried out using a combination of field sampled data and common GIS data layers. The results demonstrate the potential for neural network analysis in this type of environmental problem.

This study combined an intensive site-specific inventory of the spider family Salticidae with an extensive taxonomic review of a subset of the family throughout the Neotropics. This collection of over 8,000 adult salticids from lowland rainforest in Costa Rica's La Selva Biological Station yielded 103 species from 50 genera. At least one genus and ten to fifty percent of these species are new to science. Natural history and range information is presented for the sixteen most abundant species in understory and canopy fogging samples. Species richness estimators predict that quantitative understory sampling captured 88% to 98% of the species accessible to our methods during the survey period. We use this unusually comprehensive empirical dataset to evaluate performance of six parametric and seven nonparametric species richness estimators. Among parametric curve-fitting models, Soberon and Llorente's log model provides the best fit, least bias, and most accurate results at most sample sizes. Of nonparametric estimators, Chao1 and Chao2 most quickly reduce the negative bias all show at small sample sizes. Stratifying sampling by method, habitat, and site improved richness estimation by enabling us to diagnose edges of our target community and its partitions by identifying "leakage" of rare species from other partitions in which these species were common. Stratified sampling also revealed differences in subfamily-level faunal composition across partitions and exposed hints of elaborate niche partitioning among taxa, particularly within the speciose genus Corythalia. This taxonomic revision of the Neotropical genera Cobanus F. O. Pickard-Cambridge 1901 and Sidusa, Peckham and Peckham 1896 shows them to be closely related to one another and almost doubles the size of each. Twenty-four species are newly described here, twelve re-described, three synonymized, two transferred to other genera, and several recognized as being misplaced. This paper provides character matrices for specimen identification and summarizes known distribution and natural history information for all species of Cobanus and Sidusa. Phylogenetic analysis of morphological characters in these species and members of thirty other euophryine genera supports the sister relationship and mutual monophyly of Cobanus and Sidusa, and provides insight into character variation and higher-level relationships within the subfamily Euophryinae.

The conservation of marine ecosystems is at least 20 years behind terrestrial and freshwater ecosystems due to the difficulties in studying and monitoring these dynamic and complex environments. Furthermore, marine environment receive less attention because human impacts are less visible in the sea, and oceans are viewed as global commons. The purpose of the present dissertation is to contribute to the knowledge of marine conservation through the development of three components in natural resources management: inventory, monitoring, and assessment of impacts. I elaborate a multi-taxa inventory, identify key species to monitor, characterize one of the key species, and assess the impacts of the most important fishery in the community-based controlled marine area of the Seri Indians along the Sonoran desert coast of Mexico. A total 657 species of mollusks, echinoderms, sharks, rays, bony fish, sea turtles, sea snake, aquatic birds and marine mammals were recorded in the Seri territory through review of 30 scientific collections housed in museums and universities, literature, and field collections. The fish information was improved through the analysis of 151 traditional Seri names. Fifty species were identified for monitoring ecosystem health. They represent species with a legal status, rare, commercially important, taxa that dominate or characterize entire communities, common taxa, and species recognized in the Seri culture. The annual eelgrass (Zostera marina atam) was selected as a key species inside the Canal de Infiernillo in the Seri territory. Coverage of the eelgrass beds was estimated using aerial photographs, field mapping, and Seri traditional ecological knowledge. The total extent of the eelgrass beds was approximately 6687 ha, which regrew in the same areas during the three-year study, maintaining the same general shapes and sizes. Twenty-six percent of the eelgrass beds overlap with the swimming crab (Callinectes bellicosus) fishing zones. Major impact on this fishery are caused by "ghost" fishing traps, which continue to capture crabs and animals and modify the substrate as they are moved around by currents and accumulate on the sea bottom. Efforts to standardize the use of traps will reduce these impacts on this fishery in the long term.