Bat predation and the evolution of frog vocalizations in the neotropics

Bat predation has probably had an important influence on the evolution of frog vocalizations in the Neotropics. The rate at which fringe-lipped bats capture frogs is significantly higher when the frogs are calling. These bats respond to a wide variety of calls from edible frogs, and, when simultaneously presented with a choice, choose the recorded call of a palatable species over that of a poisonous species and the call of a small species over that of one too large to capture. Thus the selective advantages of loud, rapid mating calls in anurans are balanced by an increased risk of predation.     

Signal perception in frogs and bats and the evolution of mating signals

Psychophysics measures the relationship between a stimulus's physical magnitude and its perceived magnitude. Because decisions are based on perception of stimuli, this relationship is critical to understanding decision-making. We tested whether psychophysical laws explain how female túngara frogs (Physalaemus pustulosus) and frog-eating bats (Trachops cirrhosus) compare male frog calls, and how this imposes selection on call evolution. Although both frogs and bats prefer more elaborate calls, they are less selective as call elaboration increases, because preference is based on stimulus ratios. Thus, as call elaboration increases, both relative attractiveness and relative predation risk decrease because of how receivers perceive and compare stimuli. Our data show that female cognition can limit the evolution of sexual signal elaboration.     

Initiation of behavior by single neurons: the role of behavioral context

Flying crickets avoid sources of ultrasound, possibly echolocating bats, by making rapid steering movements that turn them away from the stimulus. Electrical stimulation of a single, identified sensory interneuron (Int-1) elicits avoidance steering; depressing its response to ultrasound abolishes avoidance steering. Int-1 is necessary and sufficient for this behavior but only while the cricket is in flight. Thus, the sufficiency of Int-1 for eliciting this behavior is contingent on behavioral context.     

Bat predation and its influence on calling behavior in neotropical katydids

Insectivorous bats have influenced the development of antipredator behavior in moths, green lacewings, crickets, and mantids; until recently, such adaptations were unknown in katydids. Foliage-gleaning bats in Panama can use the female-attracting, airborne calling songs of nocturnal katydids to locate prey. They also feed heavily on these insects. Katydid species sympatric with these bats exhibit markedly reduced calling song duty cycles. Males supplement shortened songs with complex, species-specific tremulations that generate vibrations that are inaudible to bats but reach conspecific females through a shared plant substrate. Female katydids do not call audibly but are also preyed on in large numbers, perhaps as a result of moving toward calling males.     

Sonar tracking of horizontally moving targets by the big brown bat Eptesicus fuscus

When following a moving target, echolocating bats (Eptesicus fuscus) keep their heads aimed at the target's position.This tracking behavior seems not to involve predicting the target's trajectory, but is achieved by the bat's pointing its head at the target's last known position. The bat obtains frequent position updates by emitting sonar signals at a high rate. After the lag between head and target positions and the nonunity tracking gain were corrected for, bats' tracking accuracy in the horizontal plane was +/- 1.6 degree.     

Distinctive cranial and cervical innervation of wing muscles: new evidence for bat monophyly

The traditional view that Old World fruit bats (Megachiroptera) and insect bats (Microchiroptera) are closely related has been challenged by claims that Megachiroptera are the sister group to flying lemurs (Dermoptera) or Primates. We found that the specialized muscles of the rostral part of the wing in Microchiroptera and Megachiroptera receive double innervation by both the facial nerve and cervical spinal nerves, suggesting that bats are monophyletic. Innervation by the facial nerve also occurs in Dermoptera and suggests that bats and Dermoptera share a common ancestor that had wings.     

Floral acoustics: conspicuous echoes of a dish-shaped leaf attract bat pollinators

The visual splendor of many diurnal flowers serves to attract visually guided pollinators such as bees and birds, but it remains to be seen whether bat-pollinated flowers have evolved analogous echo-acoustic signals to lure their echolocating pollinators. Here, we demonstrate how an unusual dish-shaped leaf displayed above the inflorescences of the vine Marcgravia evenia attracts bat pollinators. Specifically, this leaf's echoes fulfilled requirements for an effective beacon, that is, they were strong, multidirectional, and had a recognizable invariant echo signature. In behavioral experiments, presence of the leaves halved foraging time for flower-visiting bats.     

Auditory pathways to the frontal cortex of the mustache bat, Pteronotus parnellii

In primates, certain areas of the frontal cortex play a role in guiding movements toward visual or auditory objects in space. The projections from auditory centers to the frontal cortex of the bat Pteronotus parnellii were examined because echolocating bats utilize auditory cues to guide their movements in space. An area in the frontal cortex receives a direct projection from a division of the auditory thalamus, the suprageniculate nucleus, which in turn receives input from the anterolateral peri-olivary nucleus, an auditory center in the medulla. This pathway to the frontal cortex bypasses the main auditory centers in the midbrain and cortex and could involve as few as four neurons between the cochlea and the frontal cortex. The auditory cortex is also a major source of input to the frontal cortex. This area of the frontal cortex may link the auditory and motor systems by its projections to the superior colliculus.     

Bats use echo harmonic structure to distinguish their targets from background clutter

When echolocating big brown bats fly in complex surroundings, echoes arriving from irrelevant objects (clutter) located to the sides of their sonar beam can mask perception of relevant objects located to the front (targets), causing "blind spots." Because the second harmonic is beamed more weakly to the sides than the first harmonic, these clutter echoes have a weaker second harmonic. In psychophysical experiments, we found that electronically misaligning first and second harmonics in echoes (to mimic the misalignment of corresponding neural responses to harmonics in clutter echoes) disrupts the bat's echo-delay perception but also prevents clutter masking. Electronically offsetting harmonics to realign their neural responses restores delay perception but also clutter interference. Thus, bats exploit harmonics to distinguish clutter echoes from target echoes, sacrificing delay acuity to suppress masking.     

Rapid changes in throughput from single motor cortex neurons to muscle activity

Motor cortex output is capable of considerable reorganization, which involves modulation of excitability within the cortex. Does such reorganization also involve changes beyond the cortex, at the level of throughput from single motor cortex neurons to muscle activity? We examined such throughput during a paradigm that provided incentive for enhancing functional connectivity from motor cortex neurons to muscles. Short-latency throughput from a recorded neuron to muscle activity not present during some behavioral epochs often appeared during others. Such changes in throughput could not always be attributed to a higher neuron firing rate, to more ongoing muscle activity, or to neuronal synchronization, indicating that reorganization of motor cortex output may involve rapid changes in functional connectivity from single motor cortex neurons to alpha-motoneuron pools.     

Calcium-sensitive cross-bridge transitions in mammalian fast and slow skeletal muscle fibers

The fundamental mechanism underlying the differing rates of tension development in fast and slow mammalian skeletal muscle is still unknown. Now, in skinned (membrane-permeabilized) single fibers it has been shown that the rate of formation of the strongly bound, force-producing cross-bridge between actin and myosin is calcium-sensitive in both fast and slow fibers and that the rate is markedly greater in fast fibers. The transition rates obtained at high calcium concentrations correlated with myosin isoform content, whereas at low calcium concentrations the thin filament regulatory proteins appeared to modulate the rate of tension development, especially in fast fibers. Fiber type-dependent differences in rates of cross-bridge transitions may account for the characteristic rates of tension development in mammalian fast and slow skeletal muscles.     

Retrograde viral delivery of IGF-1 prolongs survival in a mouse ALS model

Amyotrophic lateral sclerosis (ALS) is a progressive, lethal neuromuscular disease that is associated with the degeneration of spinal and brainstem motor neurons, leading to atrophy of limb, axial, and respiratory muscles. The cause of ALS is unknown, and there is no effective therapy. Neurotrophic factors are candidates for therapeutic evaluation in ALS. Although chronic delivery of molecules to the central nervous system has proven difficult, we recently discovered that adeno-associated virus can be retrogradely transported efficiently from muscle to motor neurons of the spinal cord. We report that insulin-like growth factor 1 prolongs life and delays disease progression, even when delivered at the time of overt disease symptoms.     

Dialects in elephatn seals

Threat vocalizations of male elephant seals Mirounga angustirostris vary among four populations on islands off the coast of California and Baja California, Mexico. Males at San Nicolas Island in Southern California emit sound pulses at more than double the rate of males at A?o Nuevo Island, 528 kilometers north. Mean pulse rates at San Miguel Island and Isla de Guadalupe (408 and 944 kilometers south of A?o Nuevo, respectively) are intermediate to these two. Pulse rate is homogeneous within each population and consistent in the same individual. Other properties of the calls which separate populations are pulse duration and embellishment of the initial or terminal pulse in a series. These geographical differences in vocal behavior resemble local dialects in birds and humans.     

Drilling to gabbro in intact ocean crust

Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.     

Thermoregulation in endothermic insects

On the basis of body weight, most flying insects have higher rates of metabolism, and hence heat production, than other animals. However, rapid rates of cooling because of small body size in most cases precludes appreciable endothermy. The body temperature of small flies in flight is probably close to ambient temperature, and that of flying butterflies and locusts is 5 degrees to 10 degrees C above ambient temperature. Many moths and bumblebees are insulated with scales and hair, and their metabolism during flight can cause the temperature of the flight muscles to increase 20 degrees to 30 degrees C above ambient temperature. Curiously, those insects which (because of size, insulation) retain the most heat in the thorax during flight, also require the highest muscle temperature in order to maintain sufficient power output to continue flight. The minimum muscle temperature for flight varies widely between different species, while the maximum temperature varies over the relatively narrow range of 40 degrees to 45 degrees C. As a consequence, those insects that necessarily generate high muscle temperatures during flight must maintain their thoracic temperature within a relatively narrow range during flight. Active heat loss from the thorax to the abdomen prevents overheating of the flight motor and allows some large moths to be active over a wide range of ambient temperatures. Bumblebees similarly transfer heat from the flight musculature into the abdomen while incubating their brood by abdominal contact. Many of the larger insects would remain grounded if they did not actively increase the temperature of their flight muscles prior to flight. Male tettigoniid grasshoppers elevate their thoracic temperature prior to singing. In addition, some of the social Hymenoptera activate the "flight" muscles specifically to produce heat not only prior to flight but also during nest temperature regulation. During this "shivering" the "flight" muscles are often activated in patterns different from those during flight. The muscles contract primarily against each other rather than on the wings. However, the rate of heat production during shivering and flight is primarily a function of the action potential frequency rather than of the patterns of activation. Thermoregulation is a key factor in the energetics of foraging of some of the flower-visiting insects. The higher their muscle temperature the more flowers they can visit per unit time. When food supplies are ample, bees may invest relatively large amounts of energy for thermoregulation. While shivering to maintain high body temperatures during the short intervals they are perched on flowers (as well as while in the nest), bumblebees often expend energy at rates similar to the rates of energy expenditure in flight. Unlike vertebrates, which usually regulate their body temperature at specific set points, the body temperature of insects is labile. It often appears to be maintained near the lower temperature at which the muscles are able to perform the function at hand. The insects' thermal adaptations may not differ as much from those of vertebrates as previously supposed when size, anatomy, and energy requirements are taken into account.     

Female responses to ancestral advertisement calls in tungara frogs

Phylogenetic techniques were used to estimate and reconstruct advertisement calls at ancestral nodes. These calls were used to investigate the degree of preference of female túngara frogs (Physalaemus pustulosus) for both extant and ancestral calls. Females did not discriminate between calls of males of their own species and calls at their most recent ancestral node. They also recognized calls of three extant species and at four ancestral nodes as the signals of appropriate mates. Both shared ancestral history, and call convergence might differentially influence call preferences.     

基于AT89C51单片机分诊叫号系统的设计

介绍一套分诊叫号系统的设计方法。分诊叫号控制主机由PC代替，呼叫终端由AT89C51单片机系统组成，呼叫终端带有液晶显示屏和呼叫按键，通过RXD和TXD引脚与控制主机的RS232口相连构成一套完整的系统。     

广东省蝙蝠体内汉城型汉坦病毒的检测初报

汉坦病毒是一种人兽共患病病原,通过RT-PCR 扩增汉坦病毒M 片段基因序列检测我国广东蝙蝠,首 次在广东地区健康蝙蝠样品中扩增出长度约170 bp 的汉坦病毒cDNA 片段,测序证实为汉坦病毒的M 片段序列, 同源性达到99%以上。共检测了5 个蝙蝠种类的74 只蝙蝠的咽、肛拭子样品,阳性率为12.16%。说明蝙蝠也携带和 传播汉坦病毒,是汉坦病毒的宿主动物。鉴于蝙蝠与人类关系越来越密切,提醒我们在畜牧业和种植业工作中要加 强防范蝙蝠传播病毒给家养动物和人类。     

丹顶鹤与白枕鹤语图结构分析及比较

采用Avisoft SAS-Lab软件对采自哈尔滨北方森林动物园和扎龙自然保护区的笼养丹顶鹤(Grusjaponensis)和白枕鹤(Grus vipio)的鸣声,即繁殖期对鸣、日常短鸣及幼鸟鸣声进行了语图结构分析,对丹顶鹤和白枕鹤的同源声音进行比较发现,它们的对鸣、日常短鸣及幼鸟的鸣声都具有显著的差异:白枕鹤对鸣的单音节持续时间较丹顶鹤短;丹顶鹤日常短鸣的持续时间较长,频率较高。对于幼鸟鸣声,则是白枕鹤幼鸟鸣声持续的时间更长,频率更高。     

Beyond electronic feeding: The implementation of call feeding for pregnant sows

Call feeding for pregnant sows is a novel modular extension of a conventional electronic feeder (PigTek INTEC MAC) communicating via ISOagriNET. The call feeding module (CFM) assigns individual calls to each animal of a group supplied by one feeder and trains them to associate that call with feed access. Afterwards it actively calls sows to the feeder in a variable sequence in order to minimize queuing and thereby reducing aggression, stress and injuries associated with feeding. In this paper, we describe the automatic training procedures, the principal technical design and implementation details that make call feeding applicable in practice. The automatic training consists of an initial Pavlovian conditioning during standard electronic feeding and a subsequent operant conditioning. During Pavlovian conditioning the sows may enter the feeder whenever they have remaining feed allowance. An individual acoustic signal is then played immediately before the feed is dispensed. In the operant training the sow learns by experience that she can enter the feeder only after the individual acoustic signal has been presented. The training modes and their durations are individual to each sow’s learning success. Undersupply with feed due to incomplete learning is prevented by the training routines without manual intervention by controlling automatically the proportion of operant and Pavlovian conditioning. Thus, introducing call feeding in an existing herd is possible. The implementation is further able to estimate roughly the social hierarchy and incorporates this in the calculation of the call sequence in order to attenuate feeding associated aggressions. It helps to provide the animals with a positive anticipation of safe feeding and thereby offers a suitable way to improve welfare and health of pregnant sows. Being automatically controlled, it is easy to apply and has the potential to become a promising future element of precision livestock farming.