Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references (leaves 258-287). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Among some haplorhine primates, including humans, relaxed yawns spread contagiously. Such contagious yawning has been linked to social bonds and empathy in some species. However, no studies have investigated contagious yawning in strepsirhines. We conducted an experimental study of contagious yawning in strepsirhines, testing ring-tailed and ruffed lemurs (n = 24) in a paradigm similar to one that has induced contagious yawning in haplorhines. First, in a control experiment, we investigated whether lemurs responded to projected video content in general (experiment 1). We showed them two videos to which we expected differential responses: one featured a terrestrial predator and the other a caretaker holding food. Next, to test for yawn contagion, we showed individual lemurs life-size video projections of groupmates and conspecific strangers yawning, and control footage of the same individuals at rest (experiment 2). Then, to examine whether a group context might enhance or allow for contagion, we exposed subjects to the same videos in a group setting (experiment 3). Lemurs produced alarm vocalizations and moved upward while viewing the predator, but not the caretaker, demonstrating that they do perceive video content meaningfully. However, lemurs did not yawn in response to yawning stimuli when tested alone, or with their groupmates. This study provides preliminary evidence that lemurs do not respond to yawning stimuli similarly to haplorhines, and suggests that this behavior may have evolved or become more exaggerated in haplorhines after the two major primate lineages split.

Not available / text

Thesis (Ph. D.)--University of Chicago, Committee on Evolutionary Biology, March 2003. / Includes bibliographical references (p. 223-248). Also available on the Internet.

The purpose of this study is to identify the currently supported diet and dietary niches of the Malagasy subfossil and extant lemurs. The study was conducted partially in Tsinjoarivo and Antananarivo, Madagascar in the summer of 2013. Samples were analyzed and microwear determined that the dietary niches were aligned with current literature. Grit accumulation occurs more frequently in disturbed habitats and on lower canopy levels, which suggests that human manipulation of environment can impact the dental microwear of living primates.

This dissertation investigates the relationship between Madagascar’s environment and the stress physiology of the red-bellied lemur, Eulemur rubriventer. Unique lemurid traits are proposed to have evolved in response to selection pressures unlike those in other primate habitats, and appear to be particularly suited to helping animals cope with harsh and unpredictable environments. Several hypotheses as to why lemurs evolved characteristics such as small group sizes, low basal metabolic rates, and cathemerality rest upon the untested assumption that these species are ecologically and/or reproductively stressed. This study simultaneously analyzes seasonal changes in climate, ecology, and the behavior and stress hormones (cortisol) of Eulemur rubriventer, as well as differences in these parameters across habitats with different ecological matrices. The goals of this dissertation are to: (1) evaluate the influences of seasonally varying food availability and climate upon lemur behavior and physiology, to determine whether such changes are sufficient to exert strong selective pressure; and (2) assess the additional influences of habitat composition and quality to evaluate the effects of unpredictability and habitat disturbance. Eulemur rubriventer are sensitive to seasonal environmental changes, as indicated by their time budgets, diets, and fecal cortisol levels. Overall they adopt a time minimizing strategy whereby energy is conserved by resting a majority of the time. Ripe fruit scarcity periods elicit the launch of an energy maximizing strategy whereby fecal cortisol levels and time feeding increase, and time resting decreases. Sensitivity to these influences varies across habitats. The behavioral and stress responses of groups in the undisturbed habitat (UND) were more seasonal and pronounced than those from their disturbed habitat (DIST) counterparts. Lower cortisol levels in DIST may result from a less seasonally predictable environment requiring frequent short-term responses (with possible energy deficits during critical reproductive stages yielding 3 deaths out of 5 births and out-of-season reproduction). Alternatively, the attenuated behavioral and hormonal response to environmental change in DIST may indicate a severely stressed population with insufficient energy to launch an appropriate coping response. The hypothesis that animals in DIST have adapted to frequent unpredictability due to disturbance is rejected because all animals behaviorally and hormonally respond to fruit declines, indicating that this species undergoes ecological stress. / text

Although most strepsirrhines do not exhibit apparent physical signs of sexually selected traits, researchers have suggested that olfactory communication is sexually selected. The goal of this thesis is to (1) review sexual selection theory with an emphasis on sensory communication, and (2) test whether olfactory communication is sexually selected in strepsirrhines. I examined the relationships between primate mating systems and several measures of olfactory communication in 22 species: scent marking rates, the number of scent marking methods, and the volume of the main and accessory olfactory bulbs. I also evaluated qualitative data on olfactory communication in three lemur species to determine whether they meet the criteria of a sexually selected trait. Polygynandrous and monogamous species did not significantly differ from each other in scent marking rates, scent glands, or volume of the main and accessory olfactory bulbs. Three species of strepsirrhine met all criteria of having sexually selected olfactory traits, suggesting that polygynandrous lemurs are subject to sexual selection on several levels of olfactory communication. / text

Thesis (Ph. D.)--Duke University, 2008. / Includes bibliographical references.