Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references. / Also available by subscription via World Wide Web / xi, 102 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 59-64).

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references.

How echolocation and flight evolved in modern day bats is a compelling and largely unanswered question in biology. As laryngeal echolocation in bats is typified by a bony connection between the larynx and the auditory bulla via the hyoid apparatus, we developed an evolutionary-developmental model of the hyoid to test hypotheses regarding the evolution of echolocation in bats. Using computed tomography of pre- and postnatal Jamaican fruit bats (Artibeus jamaicensis), we showed that much of the hyoid apparatus was ossified prior to parturition. This includes the stereotypical articulation of the stylohyal bone with the auditory bulla found in laryngeal echolocating bats, where the cranial end of the stylohyal is flattened and wraps around the auditory bulla. Postnatally, thyrohyal ossification coincided with the development of increased echolocation call emission rate and the development of flight. We contend that the stepwise development of the hyoid apparatus of A. jamaicensis presented here serves as a proxy for the series of transitional forms that lead to the modern day hyoid apparatus and its cranial articulation with the auditory bulla in modern day laryngeally echolocating bats.

North American bats face multiple threats, prompting an increase in bat research and conservation efforts in recent decades. Researchers often use acoustic monitoring, which entails recording bats? echolocation calls and subsequently identifying them to species, typically using automated software. Chapter 1 describes an acoustic monitoring program at eight U.S. national parks that aims to assess changes in bat populations over time. Data collected in 2016-2017 showed that activity levels of the little brown bat (Myotis lucifigus) decreased significantly while other species remained stable. Little brown bats have undergone similar population declines elsewhere due to the disease white-nose syndrome. Chapter 2 investigates whether different versions of bat call identification software are comparable to each other and how accurate they are. For the two software programs tested, agreement among versions was variable and species-dependent. Furthermore, newer versions were more conservative in assigning identifications, though not, on average, more accurate.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18846号 / 理博第4104号 / 新制||理||1590(附属図書館) / 31797 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 幸島 司郎, 教授 伊谷 原一, 教授 村山 美穂 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第19853号 / 情博第604号 / 新制||情||105(附属図書館) / 32889 / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 守屋 和幸, 教授 大手 信人, 教授 荒井 修亮 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

No description available.

Dolphins at Kolmården dolphinarium were given a set of 20 floating fish hides, in order to simulate aforaging situation. The idea was to motivate the dolphins to use echolocation, in order to differentiatebetween hides which contained fish and hides that were empty. The dolphins would access the fish hidesfor 20-minute sessions five days per week, during a total period of five weeks. The results indicated thattheir interest in the fish hides was maintained over the entire study period for all individuals, and thisinterest did not correlate with age. However, older dolphins seemed more prone to solely inspect, possiblyby using echolocation aimed towards the fish hides than to physically interact with them. Neither was theirinterest affected by the dolphins’ pre-session activities. However, not all dolphins seemed interested in fishunless given to them by care takers. Thus, some dolphins were likely less motivated in solving theecholocation task. As a pod, the dolphins’ interest in this innovative enrichment was maintained over time,and the plasticity of these fish hides would suggest a range of different setups for the future. However,when analysing the potential use of echolocation cues, theoretical calculations of the target strengthdifferences between filled and empty fish hides, together with data on the physical interactions with them,suggested that the dolphins did not use sonar cues, but resorted to more or less random manipulation of thefish hides in order to eject the fish.

We examined aspects of hearing in the red bat (Lasiurus borealis) related to its use of biosonar. Evoked potential audiograms, obtained from volume-conducted auditory brainstem responses, were obtained in two bats, and the sound pressure transformation of the pinna was measured in three specimens. Field-recorded echolocation signals were analysed for comparison. The fundamental sonar search calls sweep from 45 to 30 kHz (peak energy at 35 kHz), approach-phase calls sweep from 65 to 35 kHz (peak 40 kHz) and terminal calls sweep from 70 to 30 kHz (peak 45 kHz). The most sensitive region of the audiogram extended from 10 kHz to 45-55 kHz, with maximum sensitivity as low as 20 dB SPL occurring between 25 and 30 kHz. A relative threshold minimum occurred between 40 and 50 kHz. With increasing frequency, the acoustic axis of the pinna moves upwards and medially. The sound pressure transformation was noteworthy near 40-45 kHz; the acoustic axis was closest to the midline, the -3 dB acceptance angles showed local minima, and the pinna gain and interaural intensity difference were maximal. These results are related to the known echolocation and foraging behavior of this species and match the spectral components of approach- and final-phase calls. We conclude that coevolution with hearing prey has put a higher selective pressure on optimizing localization and tracking of prey than on improving detection performance.