The pulmonary surfactant system is a multifaceted and highly complex mixture of lipids and proteins that work to reduce the surface tension created at the air-liquid interface within the lung, and provide innate immunity to the lung. Reducing surface tension allows for lung stability, patency and functioning, a crucial task to undertake in oxygen-limiting environments, such as high altitude. The lower partial pressures of oxygen and colder ambient temperatures found at high altitude pose a functional and metabolic challenge to the lung and possibly lung surfactant as well. Therefore, we determined the effects of high altitude hypoxia on the lipids and proteins of the lung surfactant system in adult deer mice. Because deer mice are known to exhibit physiological and genetic adaptations to high altitude, we hypothesized that mice would up-regulate the amounts of lipids and proteins in order to maintain lung stability and function. Specifically, the amounts of saturated lipids will increase to aid in decreasing surface tension, thereby preventing alveolar collapse, and the proteins will have a correlated response given that lipids and proteins work in unison to lower surface tension. Furthermore, since the cholesterol component of lung surfactant is known to increase the fluidity of surfactant layer, thereby promoting proper function, we determined the changes in cholesterol amounts under hypoxia and cold temperatures. These questions were addressed by simple acclimation of mice to low (380 m) and high (3800 m) altitudes and cold (5°C) or warm (25°C) temperatures. Lung surfactant was obtained via lung lavage, lipids or proteins analyzed, blood samples taken and organs dissected.

One of the most significant evolutionary advancements in vertebrates is the evolution of homeothermic endothermy. The ability to maintain a high and constant body temperature has freed endotherms from many of the metabolic effects of fluctuating temperature and allowed endotherms to inhabit a wide range of habitats. However, endothermy is very energetically costly and not an ideal solution for many vertebrates. Despite the drawbacks, endotherms have evolved many physiological adaptations to overcome the challenges posed by challenging environmental conditions. In this dissertation I investigate several physiological adaptations endotherms have evolved to deal with the challenges imposed by these environments. Mammals living in deserts must prevent hyperthermia while maintaining proper water balance. This is problematic because the only mechanism for cooling is to evaporate water, the scarcity of which defines desert habitats. I used a phylogenetic comparative analysis to show that mammals living in arid regions have evolved mechanisms to reduce rates of total evaporative water loss. In this analysis I used many continuous variables to describe habitat in addition to classifying habitats as arid or mesic. Mammals living in cold habitats must prevent hypothermia by increasing internal heat production, which requires increased energy intake, a problem confounded by the lack of primary productivity in cold habitats. Mammals can increase heat production either by increasing their capacity for shivering or nonshivering thermogenesis. I acclimated deer mice to cold ambient temperature to show that they can increase metabolic heat production by increasing their capacity for nonshivering thermogenesis. Endotherms living at high altitudes face a two-fold problem, cold temperatures combined with limited oxygen availability. The ability to maintain body temperature and aerobic activity is dependent on oxygen. The ability to carry excess oxygen in the blood would likely be beneficial to animals living at high altitude. I tested whether or not deer mice originally from high altitude have an excess ability to carry oxygen in their blood and found that the circulatory distribution of oxygen likely sets an upper limit for aerobic performance in these animals.

My dissertation investigates the unique ways organisms put effort (energy and nutrients) towards reproduction. My research asks how, delays might allow mammals to allocate limited resources to reproduction (i.e., are delays adaptive? ) and consisted of several components aimed at understanding the causes and consequences of reproductive delays in mammals. First, using the comparative method I examined ecological predictors and evolutionary origins of delays in the Order Carnivora in over 200 species using data published data of ecological variables. In this group I evaluated what attributes of an animal's ecology (i.e. where it lives, what it eats, how seasonal its habitat is etc.) are predictors of a species exhibiting delays. My results suggest that not only are animals that live in seasonal environments, and eat seasonality abundant foods most likely to evolve delays but also species that are larger. Second, I dissected museum specimens of male bats (N = 47 species) to assess if reproductive delays facilitate sperm competition. By reviewing the literature and inspecting museum specimens of bats with different types of delays and some without delays I was able to determine that delays might facilitate postcopulatory sexual selection (competition between the sperm from different males). Using these data I addressed the hypothesis that, once delays occur, they provide an avenue for postcopulatory sexual selection. I tested the prediction that males in species with delays between mating and egg-fertilization have larger testes than males of species that do not have delays before fertilization. Third, I empirically evaluated the costs and benefits of delays in a species that has pregnancies both with and without delays, Artibeus jamaicensis. Using this system I compared energy use, milk quality and food availability between the 2 pregnancies to evaluate the hypothesis that delays allow females to time the most expensive stage of reproduction, lactation, with periods of food abundance. My dissertation contributes previously lacking data on individual and seasonal differences of how energy is divided among the different functions; body maintenance, growth or reproduction.

The importance of phenotypic plasticity during post developmental acclimation to high altitude has been recognized in the recent years. However, the relationship between morphological changes observed in the lungs resulting from this acclimation process and changes in aerobic performance at high altitude have not been sufficiently investigated. This thesis attempts to elucidate the specific morphological changes associated with changes in the lungs of adult deer mice acclimated to high altitude, and also to discern whether or not there is a relationship between aerobic performance and lung morphology at high altitude. Thus far the results show that adult deer mice have significantly greater surface area of the alveoli, and that this change seems to be the result of hypertrophy of existing alveolar tissue, as opposed to de novo alveolarization. This work also demonstrates that lung volume in deer mice is positively correlated with aerobic performance under hypoxic conditions, suggesting that the increase in lung mass of high altitude acclimated deer mice is beneficial to aerobic performance. However, this relationship is dependent on heart mass such that mice with greater heart mass receive a greater benefit from possessing larger lungs. This work highlights the importance of phenotypic changes in the lungs resulting from acclimation to high altitude.

The infectious enthusiasm of scholars speaking about their research is often perfectly complemented by the never-ending quest of academic audiences for new knowledge, making seminars one of the most forceful and efficient mechanisms for transmitting scholarly information. Indeed, seminar attendance is an integral part of the experience for University of California (UC) researchers, with an estimated 300 to 500 seminars during a typical week of the academic year across 900 departments or programs in the UC system. This translates to well over 10,000 seminars annually that are presented in diverse formats and various frequencies—weekly department, graduate group and center seminars, monthly or quarterly talks in distinguished scholar lecture series, and annual university lectures by eminent faculty.

Although the importance of sponsoring and attending research seminars is universally acknowledged by UC scholars and administrators, time and travel constraints limit the potential for maximizing transmission and exchange of the massive amount of information contained in these seminars. The schedules of researchers (particularly faculty) are often packed so tightly that they cannot accommodate the additional time needed to walk to many seminars on their own campus, let alone travel to a neighboring campus. Consequently, the number of UC researchers who attend seminars on UC campuses other than their own is negligible.

The UC Seminar Network was conceived as a way to address these time constraints and open up numerous new possibilities for information exchange by delivering scientific presentations to a researcher's office computer using webinar technology that links seminars across the 10-campus UC system. This network would increase intra-, inter-, and off-campus seminar access, encourage speaker sharing, reduce travel, augment outreach, and provide electronic feeds for on-demand streaming and archiving.