Date of Award

Fall 12-1-2006

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Advisor

Charles J. Amlaner

Second Advisor

Steven L. Lima

Third Advisor

Diana K. Hews

Abstract

Previous comparative studies of sleep identified relationships between sleep and constitutive and ecological variables. Results from these studies helped shape early hypotheses for the function of sleep; however, all were conducted without an explicit phylogenetic or theoretic framework and focused exclusively on mammals. Hence, the validity of their results and applicability to other taxa is unclear. We ( 1) reviewed the literature on sleep in animals, (2) updated and reanalyzed the mammalian dataset using independent contrasts and (3) multivariate path analysis, and ( 4) presented the first quantitative analysis of sleep in a non-mammalian taxon: birds. Following previous mammalian analyses, we gathered data on SWS time, REMS time, body and brain mass, BMR, gestation/incubation period, and predation risk while asleep for 83 mammalian and 23 avian species. For mammals, relative BMR related negatively to SWS time, a result that opposed expectations under the energy conservation hypothesis. REMS time related weakly, but positively to relative brain mass, supporting a neurological role for REMS. Time spent in REMS was also negatively related to the degree of precociality and risk of predation. We expected similar relationships between avian and mammalian SWS/REMS and constitutive and ecological variables; however, the relationships between sleep time and all constitutive variables were markedly non-significant. We identified only a strong relationship between SWS time and predation risk index. These results have important consequences for the taxonomic applicability of hypotheses for the functions of sleep.

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