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Biomedical subjects

M B Fenton

Publications and source records attributed to M B Fenton.

12 recordsLinked to original sources
PubMed2006

A tale of two siblings: multiple paternity in big brown bats (Eptesicus fuscus) demonstrated using microsatellite markers.

In many bat species, the opportunity for sperm competition or other mechanisms of post-copulatory paternity biasing is thought to be great, due to the long delay between copulation and fertilization, demonstrated sperm storage capabilities, and observed promiscuity. We present the results of the first study to assess whether litters of big brown bats (Eptesicus fuscus) containing dizygotic twins share the same father. We sampled 26 mother-offspring triads from three colonies in Indiana and Illinois, as well as 299 additional adults (237 females and 62 males) from these colonies and six other maternity colonies in the same area in 1997-1998. All individuals were genotyped at nine highly variable autosomal microsatellite loci and one X-linked locus. We assessed multiple paternity using autosomal and X-linked locus exclusions, and using maximum-likelihood methods. All methods confirmed multiple paternity within litters, and the maximum-likelihood analyses indicated that almost half of the sampled litters were composed of maternal half-siblings rather than full-siblings. Our results highlight the potential importance of post-copulatory mechanisms of paternity determination in the mating system of big brown bats, and have important implications for gene flow and population structuring in this species.

Animals↗
PubMed1995

DNA fingerprinting provides evidence of discriminate suckling and non-random mating in little brown bats Myotis lucifugus.

Recent advances in DNA extraction and fingerprinting techniques allowed examination of genetic similarity of groups of Myotis lucifugus at maternity roosts. Mean percentage band-sharing between young was significantly higher than between mothers, suggesting fertilization success skewed for individual males or male lineages. Mean percentage band-sharing between presumed mothers and young was significantly higher than band-sharing between all other groups, suggesting that Myotis lucifugus preferentially suckle their own young.

Analysis of Variance↗
PubMed1993

What ears do for bats: a comparative study of pinna sound pressure transformation in chiroptera.

Using a moveable loudspeaker and an implanted microphone, we studied the sound pressure transformation of the external ears of 47 species of bats from 13 families. We compared pinna gain, directionality of hearing and interaural intensity differences (IID) in echolocating and non-echolocating bats, in species using different echolocation strategies and in species that depend upon prey-generated sounds to locate their targets. In the Pteropodidae, two echolocating species had slightly higher directionality than a non-echolocating species. The ears of phyllostomid and vespertilionid species showed moderate directionality. In the Mormoopidae, the ear directionality of Pteronotus parnellii clearly matched the dominant spectral component of its echolocation calls, unlike the situation in three other species. Species in the Emballonuridae, Molossidae, Rhinopomatidae and two vespertilionids that use narrow-band search-phase echolocation calls showed increasingly sharp tuning of the pinna to the main frequency of their signals. Similar tuning was most evident in Hipposideridae and Rhinolophidae, species specialized for flutter detection via Doppler-shifted echoes of high-duty-cycle narrow-band signals. The large pinnae of bats that use prey-generated sounds to find their targets supply high sound pressure gain at lower frequencies. Increasing domination of a narrow spectral band in echolocation is reflected in the passive acoustic properties of the external ears (sharper directionality). The importance of IIDs for lateralization and horizontal localization is discussed by comparing the behavioural directional performance of bats with their bioacoustical features.

Animals↗
PubMed1990

Histochemical and biochemical plasticity of muscle fibers in the little brown bat (Myotis lucifugus).

Fiber composition, and glycolytic and oxidative capacities of the pectoralis, gastrocnemius, and cardiac muscles from active and hibernating little brown bats (Myotis lucifugus) was studied. The data were used to test two hypotheses: First, since hibernating bats maintain the capability of flight and make use of leg muscles to maintain a roosting position all winter, the fiber composition of the pectoralis and gastrocnemius muscles should not change with season. Second, we tested the hypothesis of Ianuzzo et al. (in press), who propose that the oxidative potential of mammalian cardiac muscle should increase with increasing heart rate while glycolytic potential should not. Our results indicate that the fiber composition of the pectoralis muscle was uniformly fast-twitch oxidative (FO) regardless of the time of year, as predicted. However, the gastrocnemius muscle exhibited a change in FO composition from 83% in active to 61% in hibernating animals. Contrary to the variable change in histochemical properties with metabolic state, a trend of reduced maximal oxidative (CS) and glycolytic (PFK) potential during hibernation in both flight and leg muscles was apparent. The oxidative potential of flight and leg muscles decreased by 15.2% and 56.5%, respectively, while the glycolytic potential of the same muscles decreased by 23.5% and 60.5%, respectively. As predicted, the glycolytic potential of cardiac muscle remained constant between active and hibernating bats, although there was a significant decrease (22.0%) in oxidative potential during hibernation.

Animals↗
PubMed1990

Ultrasound-triggered, flight-gated evasive maneuvers in the praying mantis Parasphendale agrionina. I. Free flight.

Free-flying male praying mantises Parasphendale agrionina (Gerst.) perform evasive maneuvers when stimulated by ultrasound and when attacked by hunting, echolocating bats. They do not, however, respond in any way when standing on a substratum. The maneuvers are graded in intensity with distance from the sound source: far from the source they are simple turns, whereas close to the source they are steep diving turns or spirals. The maneuvers are made under power, and the male's velocity doubles to almost 4 m s-1 by the end of a steep dive. The mantis does not show any directional preference. The behavioral threshold of 64 dB SPL and minimum latency to course change of 125 ms indicate that these mantises should have adequate time to evade bats using calls of greater than 85-90 dB SPL (at 10 cm). In field experiments with wild, hunting bats, P. agrionina successfully evaded capture in all five attacks to which they responded with evasive maneuvers. Out of three attacks on P. aeruginosa and three on a normally non-responding mantis, Miomantis paykullii Stål, in which there were no evasive maneuvers, the mantis was captured in five cases.

Animals↗
PubMed1987

Sperm-epithelium relationships in relation to the time of insemination in little brown bats (Myotis lucifugus).

Copulation lasted for up to 46 min in little brown bats. Spermatozoa were stored in both the uterus and the utero-tubal junction, although intimate relationships between spermatozoa and the epithelium were particularly evident in the utero-tubal junction, and were established at the beginning of the period of sperm storage. Polymorphonuclear leucocytes were present in all uteri irrespective of whether or not they had been inseminated but were not generally present in the utero-tubal junction or oviduct. Engulfment of spermatozoa by the epithelial cells of the utero-tubal junction and by polymorphonuclear leucocytes in the uterine glands was evident soon after copulation. It is suggested that this may effect the removal of defective spermatozoa and allow luminal spermatozoa access to the spatially restricted storage sites. Uninseminated female bats attempted to elicit copulation from torpid males, and were also observed adjacent to copulating pairs. Female bats also uttered copulation calls.

Animals↗
PubMed1979

Echolocation and pursuit of prey by bats.

Echolocating bats use different information-gathering strategies for hunting prey in open, uncluttered environments, in relatively open environments with some obstacles, and in densely cluttered environments. These situations differ in the extent to which individual targets such as flying insects can be detected as isolated objects or must be separated perceptually from backgrounds. Echolocating bats also differ in whether they use high-resolution, multidimensional images of targets or concentrate specifically on one particular target dimension, such as movement, to detect prey.

Animals↗