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Browsing by Subject "Andes"

Now showing 1 - 4 of 4
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    A new Ecuadorian species of the rare Neotropical caddisfly genus Amphoropsyche Holzenthal (Trichoptera, Leptoceridae)
    (Pensoft Publishers, 2016) Holzenthal, Ralph W.; Rios-Touma, Blanca
    A new species of the rare long-horned caddisfly genus Amphoropsyche Holzenthal is described from Ecuador, bringing the number of species known from the genus to 15. All species are very regional in their distributions and known only from very few specimens. The new species, Amphoropsyche real, is similar to a number of previously described species from Colombia (A. ayura, A. cauca, A. flinti, A. quebrada, and A. stellata) and Ecuador (A. napo and A. tandayapa). The males can be distinguished from the others by features of segment X of the male genitalia, especially the prominent midlateral and subapicodorsal spinelike setae. An updated taxonomic key to males of the genus is provided.
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    A Republic of Lost Peoples: Race, Status, and Community in the Eastern Andes of Charcas at the Turn of the Seventeenth Century
    (2017-08) Weaver Olson, Nathan
    This dissertation explores a period between the 1570s and 1620s when the Audiencia of Charcas (Modern Bolivia) was beset with problems. During this time, the Eastern Andean frontier emerged as an idealized space where the chaotic social elements that plagued Charcas, both within and without, might be more effectively placed under royal authority. The discovery and exploitation of resources in the Viceroyalty of Peru, particularly silver mines, had set in motion new patterns of human migration and mixture that would fill Spain’s Peruvian cities with a rabble that some would parse as la gente suelta: the Empire’s loose or lost peoples. This growing throng, including ambitious immigrants and disaffected children of the conquistadores, seemed to threaten the fragile order that Spanish officials had established. Moreover, Spanish control of Peru remained incomplete and tenuous. Just east of Potosi, raids of the Chiriguano and other unconquered indigenous groups crippled the development of the region’s emerging agrarian hinterland. In the frontier, idealized cities and their jurisdictions were seen as sites where royal authorities would knit together the region’s growing Spanish and mixed-race transient population, fugitive African and indigenous slaves and servants, and unconquered peoples, into an orderly republic, a community bound together under the rule of law. Over six chapters, this dissertation explores how a diverse set of actors applied Iberian ideas about vagrancy, urban planning, racial difference, and frontier geopolitics to the specific conditions of Potosí and its eastern hinterlands. I find that royal officials and prospective city founders often weighed the social reputation of frontier settlers against the realities of recruitment, allowing for social mobility by people of African descent. Unlike previous studies, which have analyzed either tensions within Potosí itself or Spain’s often violent relationships with unconquered peoples, this dissertation redefines the Eastern Andes as a contested internal space, shaped by the localized aspirations of the many people who strove to possess the region’s land and resources. In the frontier, low-status colonists elaborated new notions of collective honor, rooted in a shared heritage of frontier service, to pursue individual rights and privileges unavailable to them in Charcas’s urban core.
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    Systematics, Biogeography, and Phylogeography of Thylamys Mouse Opossums, a Recent Radiation of Neotropical Marsupials
    (2013-08) Giarla, Thomas Christopher
    This project broadly explores the systematics, biogeography, and phylogeography of Thylamys mouse opossums, a genus of Neotropical marsupials from central and southern South America. Chapter 1 is part of a collaborative work with Robert Voss and Sharon Jansa (Chapter 1). In it, we resolve longstanding issues surrounding Thylamys taxonomy and nomenclature using mitochondrial DNA sequences and morphology, and provide the first phylogenetic hypothesis for all recognized species in this genus. We recognize nine species but also uncover numerous morphologically cryptic mitochondrial haplogroups within four species. In Chapter 2, I assess the evolutionary independence of a subset of these morphologically cryptic lineages within the montane species Thylamys pallidior, T. sponsorius, and T. venustus. I find evidence to support the existence of two lineages within each of the three species, and also conduct tests to determine the number of nuclear loci needed to confidently test species limits. In Chapter 3, I examine the biogeographic history of Thylamys and its monotypic sister-genus Lestodelphys, considering the impact of habitat type and physical barriers on range evolution and cladogenesis. In Chapter 4, I test predictions regarding the impact of late Quaternary glacial cycles on the evolutionary history of six montane cryptic lineages. I estimate divergence times and demographic shifts for each lineage, and find limited support for the core predictions. Two supplementary files are provided online as part of this dissertation: a file containing 15 phylogenetic trees for each of the loci considered in Chapter 2 (Online Supplementary File 1) and a file containing GenBank accession numbers and tissue voucher numbers for the sequences included in the supermatrix in Chapter 3 (Online Supplementary File 2).
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    Understanding Tropical South American Rainfall Response to Global Climate Dynamics: A Speleothem Multi-Proxy Approach
    (2024-05) Parmenter, Dylan
    One of the greatest challenges facing climate scientists today is predicting large scale tropical rainfall response to climate change. One of the goals of speleothem paleoclimatology has been focused on using stalagmite oxygen isotopes to reconstruct tropical rainfall response to global climate processes on millennial and orbital timescales, in the hope that proxy enabled models may improve rainfall predictability. In South America, oxygen isotope records in the Andes and Amazon Basin have helped to paint a picture of large-scale rainfall response to glacial/interglacial cycles, greenhouse gasses, and ocean circulation. These studies interpret changes in oxygen isotope composition as reflecting rainout along a give moisture trajectory. While this type of analysis is informative in terms of inferring large-scale rainfall changes, complimentary proxies may help to constrain changes to specific regions, especially in cases where the moisture reaching a given site travels a long distance, or where the moisture source changed over time. In this dissertation, we have extended existing oxygen isotope records in the Eastern Amazon and Central Peruvian Andes deeper in time, with the new Amazon record pushing another 25,000 years into the Last Glacial, and the new Peru record extending another 55,000 years, now covering the entire Last Glacial Period and part of the Last Interglacial. In order to constrain rainfall to these specific regions, we analyzed Metal to Calcium ratios, which can be used as a proxy for local aridity, for both our extended portions of the records and for multiple intervals where only oxygen isotopes were published. We also replicated previously published oxygen isotope ratios with a new sample from the Central Peruvian Andes that grew over a precessional cycle during the Penultimate Glacial, and obtained Metal/Calcium ratios to test our hypotheses further in time. Our multi-proxy findings suggest that the Eastern Amazon oxygen isotope record does in fact reflect regional rainfall, and that high-latitude forcing is the primary control for Amazon rainfall variability during the Last Glacial on millennial timescales. In the Central Peruvian Andes, however, our record indicates that the majority of high-latitude forced millennial scale variability occurred further upstream. The lack of end-member shifts in our carbon isotope records from both regions suggests that vegetation did not undergo any major changes on millennial or orbital timescales over the last glacial/interglacial cycles. On orbital timescales, our records indicate that a rainfall dipole exists between the two regions, controlled by the regional Walker Circulation. During periods of higher orbital variability such as the Holocene, Last Interglacial, and Penultimate Glacial, our results suggest that this circulation pattern is controlled by regional insolation. Over the Last Glacial period when eccentricity was low, however, the pattern appears locked and does not respond to insolation, with sustained rainout in the Peruvian Andes, and higher subsidence causing overall drier conditions in the Eastern Amazon. Possible mechanisms causing this locked regional Walker Circulation include ice volume and greenhouse forcing, the latter of which also seems to have exerted a direct control on Eastern Amazon rainfall across Termination 1 and the MIS 4/3 boundary.