Life Sciences Commons^™

Flexible Phenotypes, Energetics, And Whole-Animal Performance Of Migratory Songbirds, Michael Griego

Doctoral Dissertations

Animal life has evolved innumerable strategies to adapt to a great range of environmental conditions present on earth. The physiology of free-living animals has thus been shaped to allow for maximal performance under challenging conditions and has given rise to traits that enable animals to overcome daunting ecological pressures. Few life history stages in the animal kingdom rival the intensity of annual avian migration: the extreme metabolic requirements of long-distance flight coupled with navigating vast and hostile ecological barriers results in enormously high mortality for young birds. It is therefore the main focus of this thesis to identify physiological traits …

Burrowing And Walking Mechanisms Of North American Moles, Yi-Fen Lin

Doctoral Dissertations

Moles (Family Talpidae) are a classic example of extreme specialization, in their case highly derived forelimb morphologies associated with burrowing. Despite many observations of mole burrows and behaviors gathered in the field, we know very little about how and how well moles use their forelimbs to dig tunnels and to walk within the built tunnels to collect and transport food. The first chapter investigates the effect of soil compactness on two sympatric mole species under controlled laboratory conditions. My results demonstrate that increasing soil compactness impedes tunneling performance as evidenced by reduced burrowing speed, increased soil transport, shorter tunnels, shorter …

An Integrative, Cost-Benefit Analysis On Animal Perturbations: Autotomy And Life-History Related Weight Gain, Chi-Yun Kuo

Doctoral Dissertations

The variation in behavioral traits and the adaptive significance behind such variation has been a classic question in behavioral ecology. Traits that enhance while simultaneously impose high fitness costs are particularly suitable for addressing this fundamental question, as their expressions are likely under strong selection. In this dissertation, I investigate the variation in a costly antipredator behavior and the underlying cost-benefit mechanisms. The trait of interest is the voluntary shedding of the tail, or tail autotomy, in lizards. Tail autotomy allows lizards to survive close-range encounters with predators but also has severe fitness consequences, including increased energetic demand for regeneration …

Kinetic Asymmetries During Submaximal And Maximal Speed Running, Devon H. Frayne

Masters Theses

An important issue for sports scientists, coaches and athletes is an understanding of the factors within a running stride that can enhance or limit maximal running speed. Previous research has identified many sprint-related parameters as potential kinetic limiters of maximal Center of Mass velocity (Chapman and Caldwell, 1983b; Weyand et al., 2001). Bilateral asymmetry is present for many of these parameters during running; however the degree to which such asymmetries change as running speed increases is unknown. It was hypothesized that asymmetries in key sprinting parameters would be larger at maximal speed than all other tested speeds. Kinematics and kinetics …

Performance And Signaling In The Green Anole Lizard, Justin P. Henningsen

Open Access Dissertations

Green anoles are small lizards of the Southeastern United States. They possess an extensible throat-fan called a dewlap. Males have larger dewlaps and display them more often than females. Displays occur during courtship, during agonistic interaction, and during encounters with potential predators. The size of the dewlap of male green anoles is positively correlated with maximum bite force capacity. Bite force capacity, in turn, is predictive of the winner during agonistic interactions. The correlation between these traits suggests that dewlap size may be used as a reliable signal of maximum bite force capacity. In this dissertation, I address three components …

The Contributions Of Evolutionary Divergence And Phenotypic Plasticity To Geographic Variation In The Western Fence Lizard, Sceloporus Occidentalis, Christine R. Buckley, Duncan J. Irschick, Stephen C. Adolph

Biology Department Faculty Publication Series

Local genetic adaptation and phenotypic plasticity are two mechanisms that can have marked effects on the morphology, performance, and behaviour of animals, producing geographic variation among populations. However, few studies have examined how these mechanisms interact during ontogeny to shape organismal phenotypes. We incubated eggs of the western fence lizard, Sceloporus occidentalis, from four populations (representing two latitudes and altitudes) in either a warm or cool environment in the laboratory. We then raised the hatchlings under common laboratory conditions, measured morphological and performance traits until 5 weeks of age, and compared juvenile morphology with that of field-caught adults from …

A Performance Based Approach To Distinguish Indices From Handicaps In Sexual Selection Studies, B Vanhooydonck, R Van Damme, A Herrel, Dj Irschick

Biology Department Faculty Publication Series

1. Central to theories of the evolution of conspicuous secondary sexual traits is that sexual traits honestly reflect at least one aspect of an individual's quality. In general, the reliability of sexual traits can be explained in two ways. Either sexual traits are reliable indicators of individual quality because they are costly and the costs in terms of survival are higher for an individual of low quality as compared to an individual of high quality (i.e. handicap principle) or sexual traits are reliable because of physical constraints and thus cost-free (reliability by design).
2. The distinction between indices and handicaps thus centres …

A Functional Approach To Sexual Selection, Duncan J. Irschick, Anthony Herrel, Bieke Vanhooydonck, Raoul Van Damme

Biology Department Faculty Publication Series

1. Sexual selection theory is a robust and dynamic field within evolutionary biology, yet despite decades of research, remarkably little is known of the mechanistic bases of mate choice and male competition.
2. Because many aspects of sexual selection involve dynamic movements, and are physically challenging, the limits of sexual selection may be defined by key functional and physiological variables (i.e. the ‘functional approach’).
3. We advocate the functional approach for providing mechanistic resolution on the adaptive basis of sexual structures and signals, the nature of mate choice and how males compete, among other issues.
4. An overview of recent work, highlighted in this …

Effects Of Temperature And Sex On Jump Performance And Biomechanics In The Lizard Anolis Carolinensis, Sp Lailvaux, Dj Irschick

Biology Department Faculty Publication Series

1. Temperature is known to affect whole-organism performance capacities significantly in ectotherms, but may potentially alter performance kinematics as well. Locomotor performance is a multivariate phenomenon, hence changes in temperature are probably reflected in multiple aspects of locomotion.
2. We studied the thermal sensitivity of several kinetic and kinematic jump variables, including acceleration and power output, in male and female green anole lizards, Anolis carolinensis Voigt 1832. We hypothesized that temperature would have similar effects on kinetic and kinematic variables.
3. We also tested the hypotheses that males and females would differ in jump performance, but only because of sexual dimorphism for body …

The Quick And The Fast: The Evolution Of Acceleration Capacity In Anolis Lizards, Bieke Vanhooydonck, Anthony Herrel, Raoul Van Damme, Duncan J. Irschick

Biology Department Faculty Publication Series

Although of prime ecological relevance, acceleration capacity is a poorly understood locomotor performance trait in terrestrial vertebrates. No empirical data exist on which design characteristics determine acceleration capacity among species and whether these design traits influence other aspects of locomotor performance. In this study we explore how acceleration capacity and sprint speed have evolved in Anolis lizards. We investigate whether the same or different morphological traits (i.e., limb dimensions and muscle mass) correlate with both locomotor traits. Within our sample of Anolis lizards, relative sprint speed and acceleration capacity coevolved. However, whereas the variation in relative acceleration capacity is primarily …

The Effects Of Gape Angle And Bite Point On Bite Force In Bats, Elizabeth R. Dumont, Anthony Herrel

Biology Department Faculty Publication Series

Models of mammalian mastication predict that bite force is affected by both the degree of mouth opening (gape angle) and the point along the tooth row at which force is transferred to a food item (bite point). Despite the widespread use of these models in comparative analyses, experimental data documenting bite force in non-human mammals are extremely limited. The goal of this study is to document variation in non-stimulated bite force associated with change in gape angle and bite point in a broad range of species. We focus on plant-visiting bats because they exhibit a relatively primitive cranial morphology and …