8 Matching Results

Results open in a new window/tab.

Nesting Ecology and Reproductive Correlates in the Desert-nesting Gray Gull Larus Modestus (open access)

Nesting Ecology and Reproductive Correlates in the Desert-nesting Gray Gull Larus Modestus

General objectives of my study were to describe the reproductive ecology of gray gulls in the large Lealtad colony, with emphasis on demographic parameters and physiological adaptations of eggs and chicks, which would complete some original objectives established in the early 1980's by Guerra and Fitzpatrick. Specifically, my study focused on describing, then comparing with other desert and non-desert nesting larids, interactive effects of ambient physical conditions and nest-site predation on eggs and chicks.
Date: May 1993
Creator: Aguilar Pulido, Roberto E. (Roberto Eric)
System: The UNT Digital Library
Life History Biology of the Desert Nesting Seagull Larus modestus (open access)

Life History Biology of the Desert Nesting Seagull Larus modestus

Gray gulls Larus modestus are unique among birds of northern Chile as the only species nesting in the interior Atacama Desert, and the only seagull nesting far (30 - 100 km) from surface water. During breeding-nesting (August - February) gray gulls congregate on the coast of northern Chile where they feed and initiate courtship. As early as August, breeding pairs commute daily to the inner desert to establish nesting territories, round-trip distances of 60-200 Km. During incubation (30 days) and brooding (7 days) adults alternate daily foraging flights to the coast. Afterwards, both adults forage daily for their chick(s) until fledging (ca. 60 days). Foraging flights and thermoregulatory costs during the period of maximal solar radiation, when ground temperatures may reach 61 C in the day and drop to 2 C at night, have selected for adaptations which minimize those costs: tolerance of hypothermia and hyperthermia; dark plumage; low egg-shell water vapor conductance; low standard metabolic rate; elaborate repertory of thermoregulatory behavior which allow adults to take advantage of microclimatic variations in the desert and minimize costs relative to a sympatric congenor, Larus belcheri scheduling foraging flights to take advantage of optimal atmospheric conditions and presence of forage fish (anchovies) …
Date: December 1987
Creator: Guerra Correa, Carlos Guillermo
System: The UNT Digital Library
Biodiversity and Genetic Structure of Benthic Macroinvertebrates Along an Altitudinal Gradient: A Comparison of the Windhond and Róbalo River Communities on Navarino Island, Chile (open access)

Biodiversity and Genetic Structure of Benthic Macroinvertebrates Along an Altitudinal Gradient: A Comparison of the Windhond and Róbalo River Communities on Navarino Island, Chile

Altitudinal gradients in Sub-Antarctic freshwater systems present unique opportunities to study the effect of distinct environmental gradients on benthic macroinvertebrate community composition and dispersal. This study investigates patterns in biodiversity, dispersal and population genetic structure of benthic macroinvertebrate fauna across an altitudinal gradient between two watersheds on Navarino Island in southern Chile. Patterns in diversity, density, evenness and functional feeding groups were not significantly different across the altitudinal gradient in both the Windhond and Róbalo Rivers. Taxa richness in both rivers generally increased from the headwaters of the river to the mouth, and functional feeding group patterns were consistent with the predictions of the River Continuum Concept. Population genetic structure and gene flow was investigated by sampling the mitochondrial cytochrome oxidase I gene in two invertebrate species with different dispersal strategies. Hyalella simplex (Amphipoda) is an obligate aquatic species, and Meridialaris chiloeense (Ephemeroptera) is an aquatic larvae and a terrestrial winged adult. Contrasting patterns of population genetic structure were observed. Results for Hyalella simplex indicate significant differentiation in genetic structure in the Amphipod populations between watersheds and lower genetic diversity in the Róbalo River samples, which may be a result of instream dispersal barriers. Meridialaris chiloeense exhibited weak population structure …
Date: May 2016
Creator: Pulliam, Lauren
System: The UNT Digital Library
Modeling State Repression in Argentina and Chile: A Time Series Analysis (open access)

Modeling State Repression in Argentina and Chile: A Time Series Analysis

This study is an attempt to contribute to the emerging theoretical literature on state repression. A time-series model was developed to test the hypothesis that state violence in Argentina and Chile is largely a function of four internal political factors and their interactions: 1) the inertial influence of past restrictive policies on the formulation of current policies, 2) the annual incidence of political protest demonstrations, 3) the perceived effectiveness of repressive measures on unrest, 4) and the institutionalization of military rule.
Date: December 1993
Creator: King, John Christopher
System: The UNT Digital Library
Political Factors in the Creation and Implementation of the Andean Foreign Investment Code (open access)

Political Factors in the Creation and Implementation of the Andean Foreign Investment Code

The purpose of this investigation is to examine the political factors which came into the creation and implementation of the Andean Foreign Investment Code. This study analyzes the political forces in the creation of the Code and examines the implementation of the Code in each of the Andean countries. This investigation concludes that although the Code has not been implemented uniformly in the Andean countries, it remains an important part of the Andean Common Market. In addition, the continual political consensus among the member countries is emphasized for the continuation of the Andean integration effort.
Date: August 1977
Creator: Gushiken, Anita M.
System: The UNT Digital Library
The Chilean Experience, 1970-1981 (open access)

The Chilean Experience, 1970-1981

The election of a coalition of socialists and communists in 1970 and three years later, the assumption of a military government have led to much controversy around the world. This study attempts to analyze the economic conditions prevailing in Chile from 1970 to 1981. It examines the gradual deterioration of the nation's economy under the Unidad Popular government and the recovery that has taken place with the Junta Militar de Gobierno. The implementation of a market system in 1973 has been effective in bringing the nation out of economic chaos. The balance of payments is under control, inflation has been reduced, and since 1977 the nation's GNP has had an average annual growth of 7.7 per cent.
Date: August 1981
Creator: Mackenna, Leslie R.
System: The UNT Digital Library
Salvador Allende: the Rise and Fall of a Chilean Marxist (open access)

Salvador Allende: the Rise and Fall of a Chilean Marxist

This study is concerned with describing and analyzing the factors that led to the election and subsequent defeat of Salvador Allende. The research information was selected from leading books, periodicals, government documents, archives, and newspapers. The thesis presents the political history of Allende's rise to power, the social structure that made his victory possible, the development of major programs that facilitated his ascension and that made his decision inevitable, and, finally, an analysis of his administration with observations as to why he failed. The importance of the lower class, the middle class, the military, and the United States are presented as factors contributing to Allende's victory and later accelerating Allende's fall from power.
Date: December 1975
Creator: Speaks, David L.
System: The UNT Digital Library
Niche Expansion of an Invasive Predator (Neovison vison), Prey Response, and Facilitative Interactions with Other Invasive Mammals at the Southern End of the Americas: Conservation Challenges and Potential Solutions (open access)

Niche Expansion of an Invasive Predator (Neovison vison), Prey Response, and Facilitative Interactions with Other Invasive Mammals at the Southern End of the Americas: Conservation Challenges and Potential Solutions

The Cape Horn Biosphere Reserve is located at the southern tip of South America. This large archipelago is considered one of the last pristine areas left on the world. Despite it being an unpopulated area with most of the native forest cover intact, it has not been exempt from biological invasions, one of the major drivers of biodiversity loss. Three species that naturally interact in their native range in North America – American beavers (Castor canadensis), muskrats (Ondatra zibethicus), and American mink (Neovison vison) – were independently introduced in this remote region. In my dissertation, I investigated (i) the hypothesis of niche expansion in the invasive mink population on Navarino Island towards terrestrial habitats; (ii) potential mink impact on breeding success of forest-bird populations; (iii) habitat selection of small-rodent species and their perception on the mink's novel predation risk; and (iv) the dynamics of multiple-species invasions under the hypothesis of an invasional meltdown. Additionally, I worked within the framework of environmental philosophy. I provide an example of combining ecological and cultural dimensions within the International Long-Term Ecological Research network to disentangle the ethical dilemmas that surround the management of invasive species. I finally proposed a management plan based on the …
Date: December 2017
Creator: Crego, Ramiro Daniel
System: The UNT Digital Library