Thesis (Ph. D.)--University of Wisconsin--Madison, 1974. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.A.)--University of Wisconsin. / Typescript (xerox copy). eContent provider-neutral record in process. Description based on print version record.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 2005. / Includes bibliographical references (p. 303-315). Also available on the Internet.

The genus Loricaria Linnaeus of the family Loricariidae is diagnosed as a monophyletic group based on two uniquely derived synapomorphies: lower lip surfaces covered with filiform papillae and absence of buccal papillae surrounding the dentary teeth. Loricaria are small to moderate-sized catfishes widely distributed throughout most of the major river drainages of cis-Andean South America, including the Amazon, Orinoco, Paraguay, Paraná, and smaller coastal rivers draining the Guyana and Brazilian Shields. Based on multivariate analyses of morphometric and meristic data in combination with qualitative assessment of external morphological characters, 15 nominal species are accepted as valid, with an additional nine described as new. Among the nominal species, L. lentiginosa is synonymized with L. prolixa. Loricaria carinata is resurrected from synonymy with L. cataphracta and L. simillima is treated as a junior synonym of L. carinata. Formal diagnoses, descriptions, and a key to all 24 species are provided. Phylogenetic analyses of Loricaria and related taxa (Spatuloricaria, Crossoloricaria, Planiloricaria, Brochiloricaria, Paraloricaria, and Ricola) based on a combined data set of 32 gap-coded quantitative (morphometric and meristic) characters and 24 qualitative characters derived from external morphology resulted in fully resolved, but poorly supported phylogenies under equal weights and implied weighting criteria. Implied weights analyses using a concavity constant (K) of 24-49 recovered Loricaria as a monophyletic group with L. piracicabae as basal and sister to six terminal clades containing all other species. Species originally described as Loricaria, but subsequently transferred to Brochiloricaria, Paraloricaria, and Ricola, were recovered as paraphyletic in each analysis and should be treated as congeneric with Loricaria. Distributions of Loricaria exhibit patterns of endemism similar to those documented for other groups of Neotropical fishes. Species diversity is highest in the Amazon basin (13 species, including 10 endemics), followed by the Paraguay region (5 species, including 4 endemics), Guianas region (5 species, including 2 endemics), Orinoco basin (3 species, including 2 endemics), and a single species occurring in both the São Francisco basin and drainages of Northeastern Brazil. Loricaria is apparently absent from coastal Atlantic drainages south of the São Francisco basin. Such shared patterns of endemism provide some insight into past geomorphological processes that have influenced diversification in Loricaria and serves as a foundation for further tests of biogeographic hypotheses based on phylogenetic and geological evidence.

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In the Mediterranean Andes region '(MA; 30 degrees-37 degrees S), the main rivers are largely fed by melting snowpack and provide freshwater to around 10 million people on both sides of the Andes Mountains. Water resources in the MA are under pressure because of the extensive development of industrial agriculture and mining activities. This pressure is increasing as the region faces one of its worst recorded droughts. Previous studies have pointed to El Nioo-Southern Oscillation '(ENSO) as the main climatic force impacting the MA. However, the role of decadal and multidecadal climate variability, their spatial patterns, and the recurrence of long-term droughts remains poorly studied. In an attempt to better understand these factors, spatial and temporal patterns of hydroclimatic variability are analyzed using an extensive database of streamflow, precipitation, and snowpack covering the period between 1910 and 2011. These analyses are based on the combination of correlation, principal components, and kernel estimation techniques. Despite a general common pattern across the MA, the results presented here identify two hydroclimatic subregions, located north and south of 34 degrees S. While the interannual variability associated with ENSO is slightly stronger north of 34 degrees S, the variability associated with the Pacific decadal oscillation '(PDO) and/or the interdecadal Pacific oscillation '(IPO) index shows similar patterns in both regions. However, variations produced by the IPO forcing seem to be greater in the southern subregion since 1975. The estimations presented here on drought recurrence reveal a generalized increase in dry extremes since the 1950s. These findings suggest that the northern MA is more vulnerable to changes in hydrology and climate than the southern MA.

Slow seismic velocity anomalies are commonly imaged beneath subducting slabs in tomographic studies, yet a unifying explanation for their distribution has not been agreed upon. In South America two such anomalies have been imaged associated with subduction of the Nazca Ridge in Peru and the Juan Fernandez Ridge in Chile. Here we present new seismic images of the subslab slow velocity anomaly beneath Chile, which give a unique view of the nature of such anomalies. Slow seismic velocities within a large hole in the subducted Nazca slab connect with a subslab slow anomaly that appears correlated with the extent of the subducted Juan Fernandez Ridge. The hole in the slab may allow the subslab material to rise into the mantle wedge, revealing the positive buoyancy of the slow material. We propose a new model for subslab slow velocity anomalies beneath the Nazca slab related to the entrainment of hot spot material.

The first record of milk teeth of South American fossil procyonids comes from the Late Miocene-Early Pliocene at "Farola Monte Hermoso," Buenos Aires Province, Argentina. Five extant genera of Procyonidae inhabit South America (Bassaricyon Allen, Nasuella Hollister, Potos Geoffroy Saint-Hilaire and Cuvier, Procyon Storr, and Nasua Storr). Of these only Procyon and Nasua are present in the fossil record (Late Pleistocene-Holocene), in several localities in Brazil, Uruguay, and Bolivia. In addition, six other fossil genera were named, but only two are considered valid: Cyonasua and Chapadmalania. Thus, Cyonasua encompasses ten formally named species and Chapadmalania two. The new specimen, MLP 09-X-5-1, is assigned to cf. Cyonasua. In addition, anatomical evidence implies a much more carnivorous diet in Late Miocene-Early Pleistocene procyonids than that of extant South American taxa. Finally, I examine and discuss the "competitive displacement" hypothesis regarding the extinction of native marsupial carnivores after the arrival of immigrant placental carnivores in South America.