The source level of echolocation pulses is an essential parameter because it has an impact on the range at which bats perceive their environment and, most importantly, at which they detect prey. Echolocation pulse source level is under the control of the echolocator and its operational range is likely to vary with body size and foraging habitat because these determine the operational range needed by the bat. This study thus attempted to answer the following questions; (1) is the source levels of animal acoustic signals different in different situations? (2) Does body size and foraging habitat affect the source levels of animal acoustic signals? There are only a few studies that report on the source levels of echolocation pulses of free-ranging bats because of the difficulty of measuring the distance of the bat from the recording microphone. This distance is essential in calculating source levels of echolocation pulses. I used multiple microphone array system to investigate the echolocation sound signals, three-dimensional (3-D) acoustic flight paths and source levels of echolocation pulses at 10 cm standard reference distance from the mouth of a free-flying frequency-modulated (FM) bat, Neoromicia capensis and quasi-constant frequency (QCF) bat, Tadarida aegyptiaca. The two bat species differ in body size and foraging habitat. I found as predicted, that T. aegyptiaca, the larger of the two species and an open-air aerial hawker, emitted echolocation pulses of higher source levels and therefore had greater maximum detection distances than the smaller, clutter-edge aerial hawker, N. capensis. Tadarida aegyptiaca emitted echolocation pulses with an average of 146.9±4.6 (range 137.7 - 154.8) dB peSPL during emergence from the roost and an average of 143.0±4.9 (range 136.4 - 153.3) dB peSPL during foraging, extending the known range of free-flying bats. Neoromicia capensis emitted echolocation pulses with an average of 129.3±4.0 (range 119.3 - 138.7) dB peSPL during emergence from the roost and average of 132.8±5.0 (range 117.8 - 142.9) dB peSPL during foraging. As anticipated, I found N. capensis to be emitting echolocation pulses of higher source levels during foraging than when it emerged from the roost. However, there was no significant difference in the source levels of T. aegyptiaca between emergence from the roost and foraging habitat. The estimated maximum detection distances for the three insect size categories i.e. small, medium and large was greater for T. aegyptiaca than N. capensis. My data therefore suggests that bats might adjust their echolocation pulse source levels to suit their foraging habitat and situation.

Sexual conflict can occur whenever the evolutionary interests of males and females differ, and when sexually antagonistic selection acts upon traits shared between the sexes, one or both sexes can be constrained from reaching their phenotypic optima. This intralocus sexual conflict can be characterised by a tug-of-war of allelic replacement until it is resolved, but examples of well-characterised sexually antagonistic loci are rare. This thesis investigates the basis and dynamics of intralocus sexual conflict over insecticide resistance at the Cyp6g1 locus in Drosophila melanogaster, and wing colouration in Drosophila simulans. In D. melanogaster, the Cyp6g1 locus is the site of a series of insecticide resistance alleles, one of which is sexually antagonistic when back-crossed to the old isogenic lab strain Canton-S. I investigated the presence of sexual conflict over this same allele in a recently collected and genetically heterogeneous population. I found evidence of balancing selection on resistance (Ch. 2) that could not be explained by overdominance or sex-specific dominance (Ch. 3). However, balancing selection could be explained by resistance conferring increased fecundity to females (Ch. 2-4), and decreased reproductive success to males (Ch. 4). This male cost can in turn be explained by a negative genetic correlation between reproductive success and Cyp6g1 expression (Ch. 4), possibly influencing levels of reproductive investment (Ch. 2). Additionally, I explored the dynamics of the sex-specific fitness effects of resistance across three Cyp6g1 alleles back-crossed to a single genetic background. I found no evidence of sexual antagonism, but revealed that the cost of resistance increased with more derived alleles, and that all alleles were more costly to females (Ch. 5). After decades of strong selection imposed by insecticide use an unresolved sexual conflict persists at the Cyp6g1 locus despite sexual dimorphism in resistance, and it does not appear that more derived Cyp6g1 alleles are necessarily involved in mediating this conflict. Wing interference patterns (WIPs) are a newly discovered trait subject to female mate choice in Drosophila. I explored the potential for intralocus sexual conflict over WIPs by measuring WIP traits from males and females from populations of D. simulans evolved under relaxed or elevated sexual selection. In response to sexual selection male WIPs evolved to be brighter, higher contrast, and shifted to longer wavelengths of light, but there was no associated response to selection in females (Ch. 6). While WIPs did not appear to be constrained from detectably responding to selection by acute intralocus sexual conflict, male WIPs from the relaxed selection regime were similar to female WIPs, suggesting a cost to sexually selected WIPs that may be indicative of sexually antagonistic selection. IASC is pervasive and can influence a wide range of fundamental evolutionary processes including sexual selection, speciation, and extinction. The research presented in this thesis adds to a body of evidence that sexual dimorphism does not necessarily resolve IASC, and documents the first evidence that WIPs do not appear to be subject to acute IASC and can evolve in response to sexual selection.

PhD (Zoology) / Department of Zoology / The order Rodentia is the most speciose group of mammals with muroids being the most diverse superfamily. Since they are represented in arboreal, semiaquatic, subterranean and terrestrial niches, rodents may exhibit morphological traits reflecting their adaptations to such diverse environments. This thesis focuses on the morphology of the endocranium, auditory bulla and cochlea in three tribes (Otomyini, Taterillini and Gerbillini) representing 10 species of African rodents, concentrating on their variability, function and adaptability, using micro-CT imaging and 3D shape comparative methods. Additionally, variations in cranial size were also studied in respective of global warming and climatic variables. Morphological changes/variations are a result of environmental change, therefore each chapter in this study details the effect of environmental change (in space and time) on different morphological traits i.e. general cranial size (chapter 2), cochlea and auditory bulla (chapter 3) and endocranial size and shape (chapter 4). With chapter 2 dealing specifically with climate change in its strict sense and the remaining two chapters looking at different environmental gradients. Chapter 2 tests the applicability of the “third universal response to warming” (i.e. declining body size) and the Resource Rule in two murid subfamilies, Murinae and Gerbillinae. The study shows that the third response is not as universal as only one species conformed to this response. Further, food availability (Resource Rule) was shown to be the more important factor correlated with body size variations in rodent species than Bergmann’s Rule. Chapter 3 looks at the auditory bulla and cochlea, the morphological traits that play a role in hearing capabilities of rodents. I found, with some exceptions, that bulla and cochlea modifications between species could be explained by environment, phylogeny and/or allometry. In addition, I concluded that true desert adapted laminate-toothed rats and gerbils use both bulla and associated cochlea hypertrophy. Chapter 4 shows larger brain size in Taterillini and two species of Otomyini, with life histories and environment being the most probably factors responsible for xiv this. Using a novel method of diffeomorphism (deformation models), there was more variation in endocranial morphology between the gerbils and laminate-toothed rats than within them with olfactory bulb, paraflocculi, and posterior ventral cortex showing the most variability. Overall, this thesis shows that variations in the morphological traits studied are strongly influenced by the environment and function. / NRF

Sensory pollution from artificial night-lighting and anthropogenic noise have increased at a dramatic rate over the last several decades. Alterations to the sensory environment have been found to affect wildlife in a wide variety of ways including behavioral changes, physiological responses, changes in species interactions, and altered community structure. Increased levels of light and noise pollution can originate from many sources including roads, energy development and infrastructure, and urbanization. Even remote or protected areas are not immune to the effects of increased sensory disturbances with 63 percent of protected areas within the United States found to have been exposed to a doubling of background noise levels due to anthropogenic activity and skyglow, the scattering of artificial light by the atmosphere, extending hundreds of kilometers from the source. Despite a large body of work investigating the effects of light or noise pollution acting alone, relatively few studies have examined the effects of both stimuli acting together even though they frequently co-occur. Better understanding how these stressors, especially when present simultaneously, are affecting ecosystems is critical to ongoing mitigation and conservation efforts. In Chapter 1, we investigated the effects of increased levels of light and noise pollution, both singularly and in tandem, on pinyon mouse (Peromyscus truei) activity and body condition. Using a full factorial study design allowed us to isolate the effects of both stimuli when acting alone as well as any potential interactions between the two when both were present. We used standard trapping methods across a gradient of light, noise, and both combined while also accounting for variations in moonlight, vegetative structure, and weather. We found that an increased level of artificial night-lighting resulted in lower trap success of pinyon mice while there was no effect of noise on trap success. There was no effect of elevated light levels on body condition but there was a negative effect of noise on body condition early in the season. Later in the season, neither light nor noise influenced body condition. No interactive effects between light and noise were found. In Chapter 2, we studied the effects of anthropogenic light and noise, singularly and in tandem, on species richness and community structure using camera traps in a manipulative field experiment. We investigated these effects at both the species level and the taxonomic level (nocturnal mammals, diurnal mammals, lagomorphs, birds, mesocarnivores, and ungulates). We showed that both light and noise pollution did alter species richness and that these effects can differ depending on the scale of observation. Increased levels of night-lighting had a scale-dependent effect on species richness such that increases in light levels had a negative effect on richness at the camera level, but light-treated sites had the highest estimated cumulative richness. In contrast, noise was found to have a negative effect on richness for birds. When both stimuli were present, the addition of night-lighting mitigated the effects of noise for birds. For community structure, noise-treated sites were the most dissimilar from other treatments, indicating that increased levels of anthropogenic noise likely have the largest effect on community structure in this study. We also found evidence of a possible rescue effect of light that counteracts the negative effect of noise. That is, combined treatment sites were significantly dissimilar from both light and noise sites but not from the control sites. Together, our results provide evidence that alterations to the sensory environment from anthropogenic activity can affect wild animal populations in multiple ways. As human development increases to meet the demands of growing human populations, more ecosystems will be exposed to increased levels of sensory disturbance, making the understanding of how these changes affect wildlife critical to ongoing conservation efforts.

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<p>An understanding of sensory ecology, how animals receive and respond to their environment, can be a powerful tool for the conservation of endangered species because it can allow us to assess the potential success of actions designed to mitigate particular threats. We have a general understanding of how sea turtles perceive and respond to certain visual, magnetic, and chemical cues, but we understand very little about how they perceive and respond to acoustic cues. This dissertation explores the acoustic ecology of sea turtles, focusing on their auditory capabilities, responses to acoustic stimuli and the implications of this knowledge for their conservation. I measured the underwater and aerial hearing sensitivities of juvenile green (Chelonia mydas), hatchling leatherback (Dermochelys coriacea), and hatchling hawksbill (Eretmochelys imbricata) sea turtles by recording auditory evoked potential responses to tonal stimuli. Green turtles detected tonal stimuli between 50 and 1,600 Hz underwater (maximum sensitivity: 200-400 Hz) and 50 and 800 Hz in air (maximum sensitivity: 300-400 Hz), leatherbacks detected tonal stimuli between 50 and 1,200 Hz underwater (maximum sensitivity: 100-400 Hz) and 50 and 1,600 Hz in air (maximum sensitivity: 50-400Hz), and hawksbills detected tonal stimuli between 50 and 1,600 Hz in both media (maximum sensitivity: 200-400 Hz). Sea turtles were more sensitive to aerial than underwater stimuli when audiograms were compared in terms of sound pressure, but they were more sensitive to underwater stimuli when audiograms were compared in terms of sound intensity. I also examined the behavioral responses of loggerhead sea turtle (Caretta caretta) to simulated low frequency acoustic deterrent devices (ADDs) and found that these turtles exhibited a mild, aversive response to these sounds. This finding indicates that low frequency tonal ADDs have the potential to warn sea turtles of the presence of fishing gear and suggest that field tests of ADDs are warranted. Finally, I conducted a comprehensive review of our knowledge of the acoustic ecology of sea turtles, examined the sources of marine anthropogenic sound sea turtles are able to detect, evaluated the potential physiological and behavioral effects of anthropogenic sound, identified data gaps, and made recommendations for future research.</p> / Dissertation

abstract: Why do many animals possess multiple classes of photoreceptors that vary in the wavelengths of light to which they are sensitive? Multiple spectral photoreceptor classes are a requirement for true color vision. However, animals may have unconventional vision, in which multiple spectral channels broaden the range of wavelengths that can be detected, or in which they use only a subset of receptors for specific behaviors. Branchiopod crustaceans are of interest for the study of unconventional color vision because they express multiple visual pigments in their compound eyes, have a simple repertoire of visually guided behavior, inhabit unique and highly variable light environments, and possess secondary neural simplifications. I first tested the behavioral responses of two representative species of branchiopods from separate orders, Streptocephalus mackini Anostracans (fairy shrimp), and Triops longicaudatus Notostracans (tadpole shrimp). I found that they maintain vertical position in the water column over a broad range of intensities and wavelengths, and respond behaviorally even at intensities below those of starlight. Accordingly, light intensities of their habitats at shallow depths tend to be dimmer than terrestrial habitats under starlight. Using models of how their compound eyes and the first neuropil of their optic lobe process visual cues, I infer that both orders of branchiopods use spatial summation from multiple compound eye ommatidia to respond at low intensities. Then, to understand if branchiopods use unconventional vision to guide these behaviors, I took electroretinographic recordings (ERGs) from their compound eyes and used models of spectral absorptance for a multimodel selection approach to make inferences about the number of photoreceptor classes in their eyes. I infer that both species have four spectral classes of photoreceptors that contribute to their ERGs, suggesting unconventional vision guides the described behavior. I extended the same modeling approach to other organisms, finding that the model inferences align with the empirically determined number of photoreceptor classes for this diverse set of organisms. This dissertation expands the conceptual framework of color vision research, indicating unconventional vision is more widespread than previously considered, and explains why some organisms have more spectral classes than would be expected from their behavioral repertoire. / Dissertation/Thesis / Doctoral Dissertation Biology 2016

Endocranial morphology provides evidence of sensory ecology and sociality of extinct vertebrates. The Earliest Pliocene Gray Fossil Site (GFS) of NE Tennessee features a conspicuous dominance of skeletal elements belonging to the dwarf tapir, Tapirus polkensis. Numerous individuals in one fossil locality often suggests gregarious behavior, but sociality in T. polkensis contradicts behavior documented for extant Tapirus species. I test T. polkensis for variation in sensory and social ecology using computed tomography and 3D digital endocasts from an ontogenetic sequence. I compare the T. polkensis endocasts with extant Tapirus species using Encephalization Quotients (EQs) and 3D geometric morphometrics. Results show conserved endocast morphology for Tapirus, and thus, conserved sensory and social ecology. Tapirus behavior is likely consistent for ~5 Ma, and extant Tapirus behavior can be inferred for T. polkensis. The large number of individuals from the GFS is likely the result of a preservation bias unrelated to gregariousness.