Browsing by Subject "Lemurs"
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Item Effects of the Distribution of Female Primates on the Number of Males(Public Library of Science, 2011-05-16) Carnes, Laurel Mariah; Nunn, Charles L.; Lewis, Rebecca J.The spatiotemporal distribution of females is thought to drive variation in mating systems, and hence plays a central role in understanding animal behavior, ecology and evolution. Previous research has focused on investigating the links between female spatiotemporal distribution and the number of males in haplorhine primates. However, important questions remain concerning the importance of spatial cohesion, the generality of the pattern across haplorhine and strepsirrhine primates, and the consistency of previous findings given phylogenetic uncertainty. To address these issues, we examined how the spatiotemporal distribution of females influences the number of males in primate groups using an expanded comparative dataset and recent advances in Bayesian phylogenetic and statistical methods. Specifically, we investigated the effect of female distributional factors (female number, spatial cohesion, estrous synchrony, breeding season duration and breeding seasonality) on the number of males in primate groups. Using Bayesian approaches to control for uncertainty in phylogeny and the model of trait evolution, we found that the number of females exerted a strong influence on the number of males in primate groups. In a multiple regression model that controlled for female number, we found support for temporal effects, particularly involving female estrous synchrony: the number of males increases when females are more synchronously receptive. Similarly, the number of males increases in species with shorter birth seasons, suggesting that greater breeding seasonality makes defense of females more difficult for male primates. When comparing primate suborders, we found only weak evidence for differences in traits between haplorhines and strepsirrhines, and including suborder in the statistical models did not affect our conclusions or give compelling evidence for different effects in haplorhines and strepsirrhines. Collectively, these results demonstrate that male monopolization is driven primarily by the number of females in groups, and secondarily by synchrony of female reproduction within groups.Item Olfactory communication and sexual selection in strepsirrhines(2009-12) Toborowsky, Carl Joshua; Lewis, Rebecca J., 1972-; Kirk, Edward C.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.Item The convergent evolution of mammalian reliance on a 'keystone vegetation structure' in Madagascar and Australia(2019-12) Romanello, Domenic Michael; Lewis, Rebecca J., 1972-Tree hollow inhabitance is a trait that has evolved multiple times over the course of mammalian evolution, but the selective pressures for this trait are not well-understood, especially in the tropics. In Australia, there are 35 species of tree hollow-inhabiting marsupials (75% of the continent’s arboreal marsupials). The adaptive radiation of Australian tree hollow inhabiting mammals is hypothesized to have been driven by thermoregulatory demands and constrained by tree hollow abundance and body size. Because Australia exhibits disparate temperature extremes and the highest tree hollow abundance globally, the continent can support a high diversity of tree hollow inhabiting species. However, tree hollow inhabitance has not been investigated similarly in the tropics, and there is a paucity of data on tree hollow abundance in low-latitude forests. My investigation of tree hollow inhabitance in Madagascar identified 36 species of tree hollow-inhabiting lemurs, comparable to the mammalian tree hollow inhabitant species richness of Australia. I hypothesized that tree hollow inhabitance within Madagascar was driven by thermoregulatory demands and constrained by tree hollow abundance and body size. I tested this hypothesis by comparing the selective pressures and constraints acting on lemuriform tree hollow inhabitants, lemuriform non-tree hollow inhabitants, and tree hollow inhabitant marsupials in Australia. Because data on tree hollow abundance are lacking in Madagascar, I used a proxy for tree hollow abundance: mean yearly rainfall, which positively correlates with global tree hollow abundance. Within Madagascar, tree hollow inhabitant sites did not differ in thermoregulatory demands or tree hollow abundance, but non-tree hollow inhabiting lemuriformes were significantly larger than tree hollow inhabiting lemuriformes. Furthermore, tree hollow inhabitant sites in Madagascar had significantly higher rainfall levels (suggesting high tree hollow abundance) than Australian tree hollow inhabitant sites, but Australian tree hollow inhabitant sites had significantly higher temperature variability (suggesting higher thermoregulatory demands) than tree hollow inhabitant sites in Madagascar. Therefore, the species richness of mammalian tree hollow inhabitants in both regions may be due to different selective pressures. Because nearly 80% of tree hollow inhabiting lemuriformes are critically endangered, endangered, or vulnerable, understanding the selective pressures and constraints for inhabitance of this keystone vegetation structure is critical to conserving tree hollow inhabitant species threatened with extinction.