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PubMed2005

Molecular phylogeny of North American long-eared bats (Vespertilionidae: Corynorhinus); inter- and intraspecific relationships inferred from mitochondrial and nuclear DNA sequences.

The taxonomy of the North American big-eared bats, genus Corynorhinus, was revised by Handley [Handley, C.O., 1959. A revision of the American bats of the genera Euderma and Plecotus. Proc. U.S. Nat. Mus. 110, 95-246] using a morphological systematics approach. Handley employed 17 morphological characters and identified only four characters that reliably differentiated the three species he recognized, C. townsendii, C. rafinesquii, and C. mexicanus. All three species have been shown to lead relatively sedentary lives and have a wing morphology that limits long-distance dispersal. Further, populations of two species, C. townsendii and C. rafinesquii, are considered to be declining. Handley [Handley, C.O., 1959. A revision of the American bats of the genera Euderma and Plecotus. Proc. U.S. Nat. Mus. 110, 95-246] recognized five subspecies of C. townsendii (C. t. australis, C. t. ingens, C. t. pallescens, C. t. townsendii, and C. t. virginianus) and two of C. rafinesquii (C. r. rafinesquii and C. r. macrotis). Two C. townsendii subspecies, C. t. ingens and C. t. virginianus, are listed as endangered under the Endangered Species Act. These facts and the lack of a thorough molecular systematic examination of this genus were the impetus for this study. Using mitochondrial and nuclear intron DNA sequences, a molecular phylogeny was inferred. The combined DNA phylogeny supports Handley's [Handley, C.O., 1959. A revision of the American bats of the genera Euderma and Plecotus. Proc. U. S. Nat. Mus. 110, 95-246] designation of three species. Further the endangered subspecies, C. t. ingens and C. t. virginianus are corroborated, as were the monophyly of the other subspecies. However, the geographical ranges of two of these subspecies, C. t. pallescens and C. t. townsendii, are revised based on biogeographic distributions as understood from our results. Estimates of timing of divergences indicate that the three species, C. townsendii, C. rafinesquii, and C. mexicanus may have diverged before Pleistocene climatic oscillations began, and therefore their cladogenesis was not the result of those processes. However, subspecific divergences within C. townsendii appear to have occurred during and been driven largely by the climatic processes of the Pleistocene Epoch. We propose new hypotheses of dispersal scenarios that may have led to the current biogeography of these lineages.

Animals↗

PubMed2003

Vitamin D metabolism in a frugivorous nocturnal mammal, the Egyptian fruit bat (Rousettus aegyptiacus).

The nocturnal, frugivorous Egyptian fruit bat (Rousettus aegyptiacus) has no obvious access to either endogenous or dietary sources of vitamin D. We hypothesized that this species under natural conditions would be vitamin D deficient and that both serum mineral concentrations and vitamin D metabolite concentrations would be low. Both wild populations and captive populations appear to have an impoverished vitamin D status, as concentrations of the principle circulating metabolite, 25-hydroxyvitamin D [25(OH)D] are undetectable (<4 ng/mL) and those of the active metabolite, 1,25-dihydroxyvitamin D [1,25(OH)(2)D] are low. Intraperitoneal administration of labelled 25(OH)D revealed enhanced 1 alpha-hydroxylase activity confirming a natural state of vitamin D deficiency. This may account for the undetectable levels of 25(OH)D; for limited amounts of the prohormone substrate are rapidly converted to the active hormone. Both vitamin D(2) and D(3) metabolites were detected in bat serum, albeit in very small amounts, inferring that in their natural habitat fruit bats may have limited access to both exogenous dietary sources and endogenous sources. Despite the low levels of vitamin D metabolites in wild-caught and captive D-unsupplemented individuals, serum mineral concentrations were well regulated and similar to those of bats receiving D-supplements, with no pathological problems associated with vitamin D deficiency evident.

Alkaline Phosphatase↗

PubMed1997

Gastric Na+K+ATPase activity and intestinal urea hydrolysis of the common vampire bat, Desmodus rotundus.

The blood diet of the vampire bat represents an extraordinarily high ratio of protein to other nutrients and the highest water consumption per body weight of any other mammal. This bat has a unique gastrointestinal morphology that is characterized by a reduced small intestine, absence of a large intestine and intestinal cecum and the presence of a water-absorptive gastric fundus. The present study demonstrates that the gastric fundus has a greater Na+K+ATPase activity for active ion transport compared with other equally sized mammals. This activity is believed to be necessary to establish a gradient favoring water absorption across what would otherwise be an osmotic disequilibrium. The absence of a large intestine and intestinal cecum may reflect a reduced urea hydrolysis by the vampire bat. The present study demonstrated that the vampire bat does not hydrolyze urea as does an equally sized non-sanguinivorous mammal. These data suggest that the blood diet and the relocation of water-absorptive tissue from the lower intestinal tract to the stomach is associated with an active ion transport mechanism in the gastric tissue and a reduced capacity for ureolytic microbes to hydrolyze urea in the intestine. Both processes are specializations for a diet high in protein and water.

Animals↗

PubMed2002

Excitatory and facilitatory frequency response areas in the inferior colliculus of the mustached bat.

In the mustached bat's central nucleus of the inferior colliculus (ICC), many neurons display facilitatory or inhibitory responses when presented with two tones of distinctly different frequencies. Our previous studies have focused on spectral interactions between specific frequency bands contained in the bat's sonar vocalization. In this study, we describe excitatory and facilitatory frequency response areas across all frequencies in the mustached bat's audible range. We show that many neurons in the ICC have more extensive frequency interactions than previously documented. We recorded responses of 96 single units to single tones and combinations of two tones. Best frequencies of the units ranged from 59-15 kHz. Forty-one units had a single, excitatory frequency response area. The rest of the units had more complex frequency tuning that included multiple excitatory frequency response areas and facilitatory frequency response areas. Some of the facilitatory frequency interactions were between one sound with energy in a sonar frequency band and a second sound with energy in a non-sonar frequency band. We also found that neurons could be facilitated by more than one additional frequency band. Our findings of extensive frequency interactions in the ICC of the mustached bat suggest that some neurons may be well suited for the analysis of complex sounds, possibly including social communication sounds.

Acoustic Stimulation↗

PubMed2003

Hearing in American leaf-nosed bats. III: Artibeus jamaicensis.

We determined the audiogram of the Jamaican fruit-eating bat (Phyllostomidae: Artibeus jamaicensis), a relatively large (40-50 g) species that, like other phyllostomids, uses low-intensity echolocation calls. A conditioned suppression/avoidance procedure with a fruit juice reward was used for testing. At 60 dB SPL the hearing range of A. jamaicensis extends from 2.8 to 131 kHz, with an average best sensitivity of 8.5 dB SPL at 16 kHz. Although their echolocation calls are low-intensity, the absolute sensitivity of A. jamaicensis and other 'whispering' bats does not differ from that of other mammals, including other bats. The high-frequency hearing of A. jamaicensis and other Microchiroptera is slightly higher than expected on the basis of selective pressure for passive sound localization. Analysis suggests that the evolution of echolocation may have been accompanied by the extension of their high-frequency hearing by an average of one-half octave. With respect to low-frequency hearing, all bats tested so far belong to the group of mammals with poor low-frequency hearing, i.e., those unable to hear below 500 Hz.

Animals↗

PubMed1997

Audiogram of the big brown bat (Eptesicus fuscus).

The audiograms of three big brown bats (Eptesicus fuscus) were determined using a conditioned avoidance procedure. The average audiogram ranged from 0.850 kHz at 106 dB to 120 kHz at 83 dB SPL, with a best threshold of 7 dB at 20 kHz and a distinct decrease in sensitivity at 45 kHz. The results confirm those of a previous study by Dalland (1965a) that the big brown bat has good high-frequency hearing coupled with poor low-frequency hearing. Comparative analysis suggests that the bat's good high-frequency hearing initially evolved for passive sound localization and that it was later coopted for use in echolocation. In addition, the restricted low-frequency hearing of the big brown bat is typical of mammals with good high-frequency hearing.

Acoustic Stimulation↗

PubMed2003

The status of the Japanese and East Asian bats of the genus Myotis (Vespertilionidae) based on mitochondrial sequences.

The genus Myotis includes the largest number of species in the family Vespertilionidae (Chiroptera), and its members are distributed throughout most of the world. To re-evaluate the phylogenetic position of East Asian Myotis species with respect to Myotis species worldwide, we analyzed mitochondrial gene sequences of NADH dehydrogenase subunit 1 and cytochrome b from 24 East Asian individuals as well as 42 vespertilionid bats determined previously. The results suggest that: (1) some individuals having the same species name in Europe and Japan do not form a monophyletic clade, indicating that some bat species exhibit morphological convergence, (2) Japanese Myotis mystacinus forms a sister relationship with Myotis brandtii (Palaearctic), and both species are included in the American clade implying that an ancestor of these species originated in North America, and (3) the Black whiskered bat, Myotis pruinosus, is endemic to Japan and forms sister relationships with Myotis yanbarensis and Myotis montivagus collected from Okinawa (Japan) and Selangor (Malaysia), respectively, implying that M. pruinosus originated from the south. The systematics of Japanese and East Asian Myotis bats were revisited by considering their phylogenetic relationships. Our study provides the first extensive phylogenetic hypothesis of the genus Myotis that includes East Asian and Japanese species.

Adaptation, Biological↗

PubMed1999

Ultrasound detection in fish--a parallel to the sonar-mediated detection of bats by ultrasound-sensitive insects?

Most bats use ultrasonic sonar signals, or cries, to locate prey. Many of their insect prey species have evolved an ability to hear and respond to these signals, and studies clearly demonstrate the survival value associated with this ability. Like bats, toothed whales locate prey by emitting ultrasonic sonar signals, or clicks. As a parallel to the insect prey of bats, it would seem obvious to assume that some fish species likewise are capable of sensing the ultrasonic clicks of their odontocete predators. As judged from classical fish audiometry literature, this seems not to be the case, however, and although in recent years some fishes have been proven responsive to ultrasound, examination of ecological and acoustic differences reveals that conclusions on ultrasound-mediated insect escape behavior are not immediately applicable to fish. This has the consequence that future experiments on fish ultrasound detection should not be looking for observations directly parallel to those observed in the bat-insect interactions.

Animals↗

PubMed1999

Anatomical and functional imaging of the auditory cortex in awake mustached bats using magnetic resonance technology.

The auditory cortex of mustached bats, Pteronotus parnellii, has been studied extensively using neuroanatomical tract-tracing and electrophysiological techniques to elucidate the functional organization and neural mechanisms important for auditory processing. While these techniques have identified several cortical maps involved in processing auditory information, there has been no direct observation of the dynamics of simultaneous activation of several discrete areas. We applied magnetic resonance (MR) imaging techniques for visualizing brain structures in awake bats using a 7-Tesla magnet system; we also investigated functional MR imaging by measuring changes in stimulus-correlated blood oxygenation levels to detect cortical areas exhibiting evoked neural activity. High resolution (100 microm) anatomical images were successfully acquired without any motion artifacts. It was possible to reconstruct the whole brain image and analyze brain surface structures with three dimensional (3D) MR imaging data. These data provide detailed morphometric measurements that will allow localization of stimulus specific neural activity patterns using modified functional magnetic-resonance-imaging (fMRI) protocols. Motion artifacts is the primary disadvantage of using awake bats; our study shows that fMRI of a bat's brain is feasible and may prove to be an important advancement for a further understanding of auditory processing in this species.Themes: Sensory systems, Neural basis of behavior.

Acoustic Stimulation↗

PubMed2002

Detection of Australian bat lyssavirus using a fluorogenic probe.

BACKGROUND: Australian bat lyssavirus (ABLV) has been transmitted to humans following a scratch or bite from an infected bat in two cases. Following a scratch or bite to a person, the bat is usually submitted for testing and diagnosis is made using a direct fluorescent antibody test on a brain smear. A nested RT-PCR assay has also been utilised to confirm diagnosis. If positive for lyssavirus, post-exposure prophylaxis is administered. OBJECTIVES: The TaqMan assay was developed to improve the diagnosis of ABLV infection, following problems encountered with the generation of spurious PCR products in the nested RT-PCR and also to reduce the high risk of contamination inherent with nested PCRs. STUDY DESIGN: RNA was extracted from 161 bat brains and the samples were compared using a conventional RT-PCR and the TaqMan based assay. Samples from a patient with an ABLV infection collected antemortem and postmortem were also tested. RESULTS: The sensitivity of the new TaqMan based PCR assay compared favourably with the nested PCR previously in use in our laboratory. This assay was able to detect RNA in samples collected antemortem and postmortem for the diagnosis of a human case of ABLV. CONCLUSIONS: The major advantage of the TaqMan based assay was the speed of diagnosis with a result within minutes of completing the PCR (a result within 4 h of receiving the specimen). This test greatly reduces the chance of false positives through the elimination of second-round PCR and the requirement for agarose gels. The assay is sensitive and specific and should be invaluable for future antemortem and postmortem diagnosis of ABLV infection in humans.

Animals↗

PubMed2000

Molecular and morphological differentiation between species of the Plagiorchis vespertilionis group (Digenea, Plagiorchiidae) occurring in European bats, with a re-description of P. vespertilionis (Müller, 1780).

The taxonomic history of the species of Plagiorchis Lühe, 1899 occurring in European bats has been very confused because of high morphological similarity between different forms/species and the inadequate initial description of P. vespertilionis (Müller, 1780). As morphological data alone have not provided enough convincing arguments to solve the problem, the sequences from the nuclear rDNA ITS region (ITS1, 5.8S and ITS2) of three species of the P. vespertilionis group (P. vespertilionis, P. muelleri Tkach & Sharpilo, 1990 and P. koreanus Ogata, 1938) occurring in European bats were used to test the validity of these species and evaluate some of the morphological characters used for the species differentiation within this group. P. elegans from birds was used as the outgroup in the analysis. All three ingroup species were clearly distinguishable using ITS sequences. Among them, P. koreanus occupied a basal position, while P. vespertilionis and P. muelleri appeared as a cluster of two closely related, derived species. ITS sequences of the specimens obtained from different hosts and/or geographical areas did not exhibit any intraspecific variability. Morphological study of the material in collections revealed characters which enable the species of Plagiorchis from bats in Europe to be distinguished. Taking into account that the type-material of P. vespertilionis. described during the 18th Century, has been lost, for nomenclatural stability, a neotype is established and described. An amended description of the type-material of P. muelleri and keys for the determination of Plagiorchis spp. from European bats are presented.

Animals↗

PubMed2000

Molecular evidence regarding the origin of echolocation and flight in bats.

Bats (order Chiroptera) are one of the few orders of mammals that echolocate and the only group with the capacity for powered flight. The order is subdivided into Microchiroptera and Megachiroptera, with an array of characteristics defining each group, including complex laryngeal echolocation systems in microbats and enhanced visual acuity in megabats. The respective monophylies of the two suborders have been tacitly assumed, although microbat monophyly is uncorroborated by molecular data. Here we present a phylogenetic analysis of bat relationships using DNA sequence data from four nuclear genes and three mitochondrial genes (total of 8,230 base pairs), indicating that microbat families in the superfamily Rhinolophoidea are more closely related to megabats than they are to other microbats. This implies that echolocation systems either evolved independently in rhinolophoids and other microbats or were lost in the evolution of megabats. Our data also reject flying lemur (order Dermoptera) as the bat sister group, indicating that presumed shared derived characters for flying lemurs and bats are convergent features that evolved in association with gliding and flight, respectively.

Animals↗

PubMed2001

Effect of acoustic clutter on prey detection by bats.

Bats that capture animal prey from substrates often emit characteristic echolocation calls that are short-duration, frequency-modulated (FM) and broadband. Such calls seem to be suited to locating prey in uncluttered habitats, including flying prey, but may be less effective for finding prey among cluttered backgrounds because echoes reflecting from the substrate mask the acoustic signature of prey. Perhaps these call designs serve primarily for spatial orientation. Furthermore, it has been unclear whether the acoustic image conveyed by FM echoes enables fine texture discrimination, or whether gleaning bats that forage in echo-cluttering environments must locate prey by using other cues, such as prey-generated sounds. Here we show that two species of insectivorous gleaning bats perform badly when compelled to detect silent and immobile prey in clutter, but are very efficient at capturing noisy prey items among highly cluttered backgrounds, and both dead or live prey in uncluttered habitats. These findings suggest that the short, broadband FM echolocation calls associated with gleaning bats are not adapted to detecting prey in clutter.

Acoustics↗

PubMed2005

Biomechanics: independent evolution of running in vampire bats.

Most tetrapods have retained terrestrial locomotion since it evolved in the Palaeozoic era, but bats have become so specialized for flight that they have almost lost the ability to manoeuvre on land at all. Vampire bats, which sneak up on their prey along the ground, are an important exception. Here we show that common vampire bats can also run by using a unique bounding gait, in which the forelimbs instead of the hindlimbs are recruited for force production as the wings are much more powerful than the legs. This ability to run seems to have evolved independently within the bat lineage.

Animals↗

PubMed2007

Hippocampal cellular and network activity in freely moving echolocating bats.

The hippocampus is crucial for episodic and spatial memory. In freely moving rodents, hippocampal pyramidal neurons show spatially selective firing when the animal passes through a neuron's 'place-field', and theta-band oscillation is continuously present during locomotion. Here we report the first hippocampal recordings from echolocating bats, mammals phylogenetically distant from rodents, which showed place cells very similar to those of rodents. High-frequency 'ripple' oscillations were also rodent-like. Theta oscillation, however, differed from rodents in two important ways: (i) theta occurred when bats explored the environment without locomoting, using distal sensing through echolocation, and (ii) theta was not continuous, but occurred in short intermittent bouts. The intermittence of theta suggests that models of hippocampal function that rely on continuous theta may not apply to bats. Our data support the hypothesis that theta oscillation in the mammalian hippocampus is involved in sequence learning and hence, theta power should increase with sensory-input rate-which explains why theta power correlates with running speed in rodents and with echolocation call rate in bats.

Action Potentials↗

PubMed2000

Mitochondrial DNA (mtDNA) reveals that female Bechstein's bats live in closed societies.

We present a microgeographic analysis of mitochondrial DNA (mtDNA) in Bechstein's bats using three sources of control region sequence variability, including a novel mtDNA microsatellite, to assess individual relatedness both within and among 10 maternity colonies. Comparison of marker variability among 268 adult females revealed little genetic variability within each colony. However, most colonies were clearly distinguished by colony-specific mitochondrial haplotypes (total n = 28). Low intracolony variability and strong haplotype segregation among colonies, was reflected by an extraordinary high FST of 0.68, indicating a very low intercolony dispersal rate of approximately one female in five generations. Haplotype distribution among 18 solitary males showed that males frequently disperse between colony locations, indicating the absence of dispersal barriers. Bechstein's bat maternity colonies are thus closed groups that comprise 20-40 females probably belonging to only one or, at most, two matrilines. The genetic population structure of Bechstein's bats is in agreement with the hypothesis that females seek familiar and, at least, partially related cooperation partners for raising their young. Alternatively strong philopatry might reflect the importance of profound roost or habitat knowledge for successful reproduction in female Bechstein's bats.

Animals↗

PubMed2000

Is the Gibraltar strait a barrier to gene flow for the bat Myotis myotis (Chiroptera: Vespertilionidae)?

Because of their role in limiting gene flow, geographical barriers like mountains or seas often coincide with intraspecific genetic discontinuities. Although the Strait of Gibraltar represents such a potential barrier for both plants and animals, few studies have been conducted on its impact on gene flow. Here we test this effect on a bat species (Myotis myotis) which is apparently distributed on both sides of the strait. Six colonies of 20 Myotis myotis each were sampled in southern Spain and northern Morocco along a linear transect of 1350 km. Results based on six nuclear microsatellite loci reveal no significant population structure within regions, but a complete isolation between bats sampled on each side of the strait. Variability at 600 bp of a mitochondrial gene (cytochrome b) confirms the existence of two genetically distinct and perfectly segregating clades, which diverged several million years ago. Despite the narrowness of the Gibraltar Strait (14 km), these molecular data suggest that neither males, nor females from either region have ever reproduced on the opposite side of the strait. Comparisons of molecular divergence with bats from a closely related species (M. blythii) suggest that the North African clade is possibly a distinct taxon warranting full species rank. We provisionally refer to it as Myotis cf punicus Felten 1977, but a definitive systematic understanding of the whole Mouse-eared bat species complex awaits further genetic sampling, especially in the Eastern Mediterranean areas.

Animals↗

PubMed2003

Litomosoides yutajensis n. sp., first record of this filarial genus in a mormoopid bat.

Twenty-five bats were trapped in Yutaje (Amazonas, Venezuela) and examined for Litomosoides (Filarioidea: Onchocercidae). Of the nine recovered bat species, only Pteronotus parnelli was infected; it is a cave-dwelling species belonging to a family, Mormoopidae, which has not previously been included in the host range of the genus. The new species, L. yutajensis n. sp., has two median cephalic bosses covered with rugosities and differs from the 15 recognized species and subspecies from bats in several characters. Alike L. molossi Esslinger, 1973, L. chandleri Esslinger, 1973 and L. chitwoodi Bain, Guerrero, Rodriguez 2003, the new species has cuticular lateral bosses on the body. Eight of 10 P. parnelli were microfilaraemic, but only three had adult worms, showing that microfilariae survive longer than adults, which could lengthen the period of transmission. No infective larvae were detected in the following macronyssid mites: 58 Ornithonyssus bacoti, Ornithonyssinae, experimentally fed on microfilaraemic bats and dissected 15 days later, and a few Radfordiella sp., Macronyssinae, recovered from P. parnelli.

Animals↗