Wing shape and echolocation are two novel adaptations in the Chiroptera and are strongly influenced by environmental conditions. Wing shape is influenced by environmental clutter. Shorter, broader wings allow for more maneuverable flight, and are advantageous for bats living in highly cluttered environments. Longer, narrower wings help bats to increase flight speed, and are best suited for bats living in more open environments. It is likely that wing shape is also influenced by temperature, given the potential for wings to act as thermoregulatory appendages. Wings provide a thermal gradient across their surfaces, dissipating excess heat from the body. However, the importance in thermoregulation in determining wing size is unknown. If thermoregulation is a strong selective pressure, bats in hotter, more arid regions should have larger wings. Environmental conditions also influence echolocation pulse design. Echolocation pulses must successfully reach a target and generate an audible echo despite atmospheric attenuation. High-duty cycle (HDC) pulses, calls with longer durations than the interval between them, are particularly useful in environments with high amount of environmental clutter. HDC echolocators use an acoustic fovea and Doppler shift compensation to detect the fluttering wings of insect prey in dense vegetation. However, the flexibility of these pulses is limited by the bat's acoustic fovea. Wing shape and echolocation combined form an adaptive complex, providing bats with a highly specialized system of foraging. Climate change poses an enormous risk to a bat's foraging success, because rising ambient temperatures are likely to change the selective pressures on wing size (due to the potential thermoregulatory benefits) as well as prey detection volumes of the bat's echolocation (because sound propagation is influenced by temperature). As an adaptive complex any selection on either wings or echolocation is likely to influence changes in the other, with consequences for the foraging efficiency of bats. The potential impact of climate change on the foraging efficiency of bats can be gauged by the bats' adaptive responses to different climatic conditions over their geographic range. I examined these two traits in different localities across the geographic range of the Cape horseshoe bat, R. capensis to determine if wing and echolocation parameters are adapted to current climatic conditions. I measured wing area and echolocation parameters at sites within the distribution of R. capensis that were representative of the different climates across its range. I measured wing areas using digital image analysis software, and I measured echolocation parameters using a microphone array system. Temperature was a predictor in the top fitting linear mixed effects models for both wing area and prey detection volume. For differences in wing area, body mass was the only significant explanatory variable. However, body mass may itself be influenced by environmental conditions. NDVI, latitude, and average winter minimum temperature significantly related to differences in prey detection volume. My results indicate geographic variation in both wing area and prey detection volume, an indication that these traits are adapted to local climate conditions. Geographic variation in wing area is a consequence of body mass, which may or may not be a function of climate. However, geographic variation in prey detection volume is directly influenced by the environment. Therefore, increases in ambient temperature due to human-induced climate change are likely to have an effect on the foraging efficiency of R. capensis.

Doctor of Philosophy / Department of Animal Sciences and Industry / Michael E. Dikeman / The objectives were to determine the effects of packaging and injection-enhancement on beef sensory attributes, postmortem proteolysis, and color. Muscles from USDA Select, A-maturity carcasses were fabricated into 2.54-cm steaks on d 7 postmortem. In Experiment 1, longissimus lumborum (n=14 pairs) muscles were used. Packaging treatments were: vacuum packaging (VP); 80% O2/20% CO2 (HiO2); 0.4% CO/35% CO2/64.6%N2 (ULO2CO); 0.4% CO/99.6% CO2; 0.4% CO/99.6% N2; or 0.4% CO/99.6% Ar. In Experiment 2, longissimus lumborum (n=12 pairs); semitendinosus (n=12 pairs); and triceps brachii (n=24 pairs) muscles from one carcass side were injection-enhanced or non-enhanced. Steaks were packaged into VP, HiO2, or ULO2CO MAP. Steaks packaged in HiO2 MAP were in dark storage (2°C) for 4 d and all other steaks for 14 d. Steaks were displayed under fluorescent lighting for 7 d. Trained color panelists assigned color scores. Steaks for tenderness, cooked color, and sensory were cooked to 70°C. Steaks packaged in VP or ULO2 with CO MAP had little or no discoloration. Steaks packaged in HiO2 MAP discolored faster (P < 0.05) and more (P < 0.05) than steaks in other packaging treatments. Steaks packaged in HiO2 MAP were less tender (P < 0.05) than other treatments at the end of display, but had 10 d less aging due to shorter dark storage. Steaks packaged in HiO2 had the lowest (P < 0.05) a* values for internal cooked color of all treatments and exhibited premature browning. Enhanced steaks were more tender (P < 0.05) than non-enhanced steaks. Sensory panelists found that non-enhanced steaks packaged in ULO2CO MAP or VP were more tender (P < 0.05), had more (P < 0.05) beef flavor, and had less (P < 0.05) off-flavors than steaks packaged in HiO2 MAP. Off-flavors for steaks packaged in HiO2 MAP often were described as oxidative and rancid. Enhanced steaks had more (P < 0.05) off-flavors than non-enhanced steaks. Postmortem proteolysis measured by desmin degradation was not affected (P > 0.05) by packaging. Steaks packaged in ULO2 plus CO MAP had superior color stability, tenderness, and sensory attributes compared to steaks in HiO2 MAP.