Predation risk strongly influences the ecology and evolution of animal behaviors. However, anti-predator responses differ among species. Tradeoffs between anti-predator abilities and foraging efficiencies across habitats can promote the coexistence of ecologically similar species. In general, larger animals may better exploit riskier habitats; smaller animals, resources at low densities. I studied two montane ground squirrels Spermophilus lateralis and Tamias minimus in Colorado. Using food trays, I determined that the smaller T. minimus foraged more efficiently near meadow edges and was competitively superior to S. lateralis there. In contrast, S. lateralis had no preference for either edge or far habitat, but was competitively superior to T. minimus farther from the edge. I predicted, correctly, the exclusion of S. lateralis from meadows with primarily edge habitat. I proposed three alternatives to explain the observed patterns of habitat use: satiation, travel cost, or perceived predation risk. In a series of manipulations of energetic costs, protective cover, and predators, I eliminated all but the predation risk hypothesis. S. lateralis perceives less risk farther from the edge of the meadow than T. minimus. Faster harvesting and running speeds might decrease perceived predation risk. S. lateralis and T. minimus both experienced diminishing returns while foraging in food trays. Due to a higher encounter rate, S. lateralis harvested seeds significantly faster than T. minimus. S. lateralis also ran faster than T. minimus (3.14 m/s and 2.13 m/s, respectively). Gregarious animals may detect predators before solitary ones. I suggest that due to differences between sensory modes, this advantage occrues only to animals using vision. Thus, I predicted that gregariousness as a predator detection strategy should evolve only in diurnal animals. To test this, I mapped diurnal activity and gregarious behavior onto a phylogeny of eutherian mammals, and than calculated their degree of association. I found strong support for my prediction. This pattern may occur in other mobile animals. The data also suggest an association between larger body size and open habitat use among diurnal, gregarious organisms, paralleling a result from Colorado ground squirrels.

Orientador: Itamar Alves Martins / Coorientador: Christiane Strüssmann / Banca: Cynthia Peralta Almeida Prado / Banca: Diego Santana / Banca: Classius de Oliveira / Banca: Arif Cais / Resumo: A história taxonômica do gênero Pseudopaludicola é bastante intrigante e confusa, devido ao pequeno tamanho, semelhanças morfológicas, escassez de caracteres de diagnósticos, e a habitual ocorrência simpátrica ou mesmo sintópica das espécies. O gênero Pseudopaludicola Miranda Ribeiro, 1926 é atualmente constituído por 18 espécies válidas distribuídas em ambientes abertos que ocorrem em toda a América do Sul. A avaliação da riqueza no gênero Pseudopaludicola é particularmente difícil devido à conservada morfologia de suas espécies. Como apontado em trabalhos anteriores do gênero, precisa-se claramente de uma revisão taxonômica. Com base em observações de material depositado em museus há muitas espécies do gênero Pseudopaludicola não descritas. Estudos filogenéticos recentes propuseram alguns rearranjos taxonômicos em Pseudopaludicola. Portanto, apresento uma abordagem integrativa que reorganiza o atual agrupamento intragenérico na tentativa de esclarecer questões taxonômicas e dos padrões de distribuição das espécies pertencentes ao gênero Pseudopaludicola. Estas espécies são indicadoras de ambientes potenciais de conservação, com importantes atribuições para subsidiar políticas de gerenciamento ambiental para a conservação da diversidade biológica. O rearranjo taxonômico implica no reconhecimento de novos grupos de espécies de Pseudopaludicola, além da revalidação, sinonimização e descrição de novas espécies / Abstract: The taxonomic historic of the genus Pseudopaludicola is intriguing and confused, due to minute size, overall morphological similarities, scarcity of diagnostic characters, and usual sympatric or even syntopic occurrence of two or more species. The genus Pseudopaludicola Miranda Ribeiro, 1926 currently comprises 18 valid species distributed in open environments throughout South America. The assessment of the number of extant species in the genus Pseudopaludicola is particularly difficult due to their conservative morphology. However, based on observations of material deposited in museums, there are many species in the genus Pseudopaludicola still waiting to be described Therefore, it is clear that the genus needs a complete taxonomic review.. Recent phylogenetic studies have proposed some taxonomic rearrangements in Pseudopaludicola. Therefore, we presented an integrative approach that to taxonomic analysis (morphometric and bioacoustic) might help to rearrange current intrageneric grouping in an attempt to clarify taxonomic and distribution patterns issues of species of the genus Pseudopaludicola. These species are indicators of potential environmental conservation, with important assignments to support environmental management policies for the conservation of biological diversity. Taxonomic rearrangement implies the recognition of new groups of species Pseudopaludicola, beyond the revalidation, synonymization, and description of new species / Doutor

Thesis (Ph. D.)--Oregon State University, 1971. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (MS)--University of Montana, 2010. / Contents viewed on February 8, 2010. Title from author supplied metadata. Includes bibliographical references.

Published also as Thesis (Ph. D.)--University of Illinois, 1929. / Cover title. "Contribution from the Zoological laboratory of the University of Illinois no. 365." Reprinted from Ecology, vol. XI, no. 2, April, 1930. "Literature cited": p. 426-431.

No description available.

No description available.

Thesis (Ph.D.) -- Flinders University, School of Biological Sciences. / Typescript (bound). Includes bibliographical references. Also available online.

Published also as Thesis (Ph. D.)--University of Illinois, 1929. / Cover title. "Contribution from the Zoological laboratory of the University of Illinois no. 365." Reprinted from Ecology, vol. XI, no. 2, April, 1930. "Literature cited": p. 426-431.

Thesis (Ph. D.)--University of Michigan, 1939. / Thesis note on label mounted on t.p. "Reprinted from Ecological monographs, 11 ... January, 1941." "Literature cited": p. 18-19.