[Dietary differences and niche partitioning in three sympatric Myotis species].

The morphology and diet characteristics of three Myotis species roosting in the same cave were studied in Anlong County, Guizhou from September to November 2005. The three mouse-eared bats were the Chinese water myotis (Myotis laniger) "body mass: (4.46±0.53) g, forearm: (34.63±1.45 mm)", fringed long-footed myotis (Myotis fimbriatus) "body mass: (5.15±1.76) g, forearm: (35.20±1.07) mm" and szechwan myotis (Myotis altarium) "body mass: (10.94±0.87) g, forearm: (45.21±1.15) mm". There were significant differences in the body masses of the three species. The forearm length of M. altarium was significantly longer than the other two species. M. laniger preyed mostly on dipsters and their larvae (79.7% in volume and 100% in frequency, Diptera). M. fimbriatus preyed mostly on dipsters and small beetles (59.6% and 91.3%, Diptera; 28.8% and 80.1%, Coleoptera). The prey of M. altarium was mostly ground-dwelling beetles (80.8% and 100%, Carabidae and Silphidae, Coleoptera). These dietary examinations indicate that the three species are highly adapted to different foraging habitats. Our work suggests that the spatial differences in foraging niches and trophic resource partitioning represent the major mechanism behind the levels of co-existence seen in this particular bat community.

Immunohistochemical evidence of cone-based ultraviolet vision in divergent bat species and implications for its evolution.

We characterized Fos-like expression patterns in the primary visual cortex (V1) by binocular flicking stimulation with UV light to investigate cone-based UV vision in four bat species representing four lineages: Hipposideros armiger and Scotophilus kuhlii, insectivores using constant frequency (CF) or frequency modulation (FM) echolocation, respectively, and Rousettus leschenaultii and Cynopterus sphinx, cave-roosting and tree-roosting fruit bats, respectively. The optic centre processing the visual image, V1, appears more distinctly immunostaining in S. kuhlii and C. sphinx after 1h of UV light stimuli while in H. armiger and R. leschenaultii, staining was no more distinct than in corresponding controls. Our immunohistochemical evidence supports differences in the distribution of cone-based UV vision in the order Chiroptera and supports our earlier postulate that due to possible sensory tradeoffs and roosting ecology, defects in the short wavelength opsin genes have resulted in loss of UV vision in CF but not in FM bats. In addition, fruit bats roosting in caves have lost UV vision but not those roosting in trees. Our results thus confirm that bats are a further mammalian taxon that has retained cone-based UV sensitivity in some species.

[Dietary composition, echolocation pulses and morphological measurements of the long-fingered bat Miniopterus fuliginosus (Chiroptera: Vespertilioninae)].

We investigated food (insect) availability in foraging areas utilized by the long-fingered bat Miniopterus fuliginosus using light traps, fish netting and fecal analysis. The dominant preys of M. fuliginosus were Lepidoptera (55%, by volume percent) and Coleoptera (38%) of a relatively large body size. M. fuliginosus has relatively long, narrow wings and a wing span of 6.58+/-0.12 and high wing loading of 9.85+/-0.83 N/m2. The echolocation calls of free flying M. fuliginosus were FM signals, with a pulse duration of 1.45+/-0.06 ms, interpulse interval of 63.08+/-21.55 ms, and low dominant frequency of 44.50+/-2.26 kHz. This study shows that the morphological characteristics and echolocation calls of long-fingered bats are closely linked to their predatory behavior.

Differential changes of regional cerebral blood flow in two bat species during induced hypothermia measured by perfusion-weighted magnetic resonance imaging.

Cerebral blood flow (CBF) of a vespertilionid bat, Miniopterus fuliginosus (M. f.), and a pteropodid bat, Rousettus leschenaultii (R. l.) was measured non-invasively during induced hypothermia (37-10°C for M. f. and 37-24°C for R. l.) with perfusion-weighted magnetic resonance imaging. In both species, the average CBF was found to decrease with rectal temperature. The patterns of hypothermia-induced regional CBF changes, however, were different between the two species. In the pteropodid bat, the extent of CBF decrease at lower rectal temperature was similar in the cortex and thalamus, resulting in an unchanged thalamus/cortex CBF ratio. In contrast, the thalamus/cortex CBF ratio in the vespertilionid species increased progressively with decreasing rectal temperature (1.52 ± 0.14 at 37 ± 1°C vs. 2.28 ± 0.29 at 10 ± 1°C). These results suggest that the manner in which the two bat species cope with low body temperature may be reflected by a differential CBF regulation between thalamus and cortex.

[Characterization and comparison of the doppler compensation acoustic wave in Hipposideros armiger].

We used the pendulum device to study Doppler-shifted compensation of great leaf-nosed bat (Hipposideros armiger). The bats' echolocation calls were recorded by the Ultrasound Detector both under the rest condition and Doppler shift condition. Then we analyzed the calls with Avisoft software. Our results suggested that when H. armiger was approaching the target, it showed positive Doppler shift compensation: call frequency and the velocity (v) were positive correlated. Call frequency fell to minimum when the bats' relative velocity reached to maximum; likewise call frequency raised to the resting condition frequency when the relative velocity became zero. Negative Doppler shift compensation occurred when bats were far away from the target. Under negative Doppler shift compensation condition, we found call frequency and velocity were positive correlated as well, and moreover, call frequency raised to maximum again while the bats had their minus direction's maximal relative velocity. However, under this status, the elevated value was much lower than the depressed value under positive compensation at the same velocity. The frequency of occurrence of negative compensation was obviously less frequent than that under positive compensation condition. Therefore, we inferred that the two characteristics of the negative Doppler shift compensation mentioned above may be the coactions consequence of the bio-structural restriction and natural selection.

Brain structures of echolocating and nonecholocating bats, derived in vivo from magnetic resonance images.

Magnetic resonance images of the brain of five species of wild bats, including three species of Microchiroptera, one species of echolocating Megachiroptera and one species of nonecholocating Megachiroptera, were obtained in vivo. The relative volumes of the inferior colliculus and the superior colliculus to the brainstem were derived from the magnetic resonance images and compared among different species. In general, the relative size of the inferior colliculus was much larger in Microchiropterans than in Megachiropterans, and in echolocating Megachiropterans than in nonecholocating Megachiropterans. The relative size of the superior colliculus was similar in these two suborders. Agreeing with the previous results and consistent with the current hypothesis that Megachiropterans originated from Microchiropterans, the results suggest that the inferior colliculus of Megachiropterans tends to degenerate during the process of evolution, as these fruit bats use more vision and smell than hearing when they forage. The results also demonstrate that magnetic resonance imaging can be used to study the neuroanatomy of wild bats noninvasively.