共查询到20条相似文献,搜索用时 421 毫秒
1.
Peter W. Alderks Joseph A. Sisneros 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(4):387-398
The auditory system of the plainfin midshipman fish, Porichthys notatus, is an important sensory receiver system used to encode intraspecific social communication signals in adults, but the response
properties and function of this receiver system in pre-adult stages are less known. In this study we examined the response
properties of auditory-evoked potentials from the midshipman saccule, the main organ of hearing in this species, to determine
whether the frequency response and auditory threshold of saccular hair cells to behaviorally relevant single tone stimuli
change during ontogeny. Saccular potentials were recorded from three relative sizes of midshipman fish: small juveniles [1.9–3.1 cm
standard length (SL), large juveniles (6.8–8.0 cm SL) and non-reproductive adults (9.0–22.6 cm SL)]. The auditory evoked potentials
were recorded from the rostral, middle and caudal regions of the saccule while single tone stimuli (75–1,025 Hz) were presented
via an underwater speaker. We show that the frequency response and auditory threshold of the midshipman saccule is established
early in development and retained throughout ontogeny. We also show that saccular sensitivity to frequencies greater than
385 Hz increases with age/size and that the midshipman saccule of small and large juveniles, like that of non-reproductive
adults, is best suited to detect low frequency sounds (<105 Hz) in their natural acoustic environment. 相似文献
2.
Joseph A. Sisneros 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(4):413-424
The plainfin midshipman fish, Porichthys notatus, is a vocal species of teleost fish that generates acoustic signals for intraspecific communication during social and reproductive
behaviors. All adult morphs (females and males) produce single short duration grunts important for agonistic encounters, but
only nesting males produce trains of grunts and growls in agonistic contexts and long duration multiharmonic advertisement
calls to attract gravid females for spawning. The midshipman fish uses the saccule as the main acoustic endorgan for hearing
to detect and locate vocalizing conspecifics. Here, I examined the response properties of evoked potentials from the midshipman
saccule to determine the frequency response and auditory threshold sensitivity of saccular hair cells to behaviorally-relevant
single tone stimuli. Saccular potentials were recorded from the rostral, medial and caudal regions of the saccule while sound
was presented by an underwater speaker. Saccular potentials of the midshipman, like other teleosts, were evoked greatest at
a frequency that was twice the stimulus frequency. Results indicate that midshipman saccular hair cells of non-reproductive
adults had a peak frequency sensitivity that ranged from 75 (lowest frequency tested) to 145 Hz and were best suited to detect
the low frequency components (≤105 Hz) of midshipman vocalizations. 相似文献
3.
Background
Surveys of ontogenetic development of hearing and sound production in fish are scarce, and the ontogenetic development of acoustic communication has been investigated in only two fish species so far. Studies on the labyrinth fish Trichopsis vittata and the toadfish Halobatrachus didactylus show that the ability to detect conspecific sounds develops during growth. In otophysine fish, which are characterized by Weberian ossicles and improved hearing sensitivities, the ontogenetic development of sound communication has never been investigated. We analysed the ontogeny of the auditory sensitivity and vocalizations in the mochokid catfish Synodontis schoutedeni. Mochokid catfishes of the genus Synodontis are commonly called squeakers because they produce broadband stridulation sounds during abduction and adduction of pectoral fin spines. Fish from six different size groups - from 22 mm standard length to 126 mm - were studied. Hearing thresholds were measured between 50 Hz and 6 kHz using the auditory evoked potentials recording technique; stridulation sounds were recorded and their sound pressure levels determined. Finally, absolute sound power spectra were compared to auditory sensitivity curves within each size group. 相似文献4.
F. Ladich H. Y. Yan 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(6):737-746
Several anabantoid species produce broad-band sounds with high-pitched dominant frequencies (0.8–2.5 kHz), which contrast
with generally low-frequency hearing abilities in (perciform) fishes. Utilizing a recently developed auditory brainstem response
recording-technique, auditory sensitivities of the gouramis Trichopsis vittata, T. pumila, Colisa lalia, Macropodus opercularis and Trichogaster trichopterus were investigated and compared with the sound characteristics of the respective species. All five species exhibited enhanced
sound-detecting abilities and perceived tone bursts up to 5 kHz, which qualifies this group as hearing specialists. All fishes
possessed a high-frequency sensitivity maximum between 800 Hz and 1500 Hz. Lowest hearing thresholds were found in T. trichopterus (76 dB re 1 μPa at 800 Hz). Dominant frequencies of sounds correspond with the best hearing bandwidth in T. vittata (1–2 kHz) and C. lalia (0.8–1 kHz). In the smallest species, T. pumila, dominant frequencies of acoustic signals (1.5–2.5 kHz) do not match lowest thresholds, which were below 1.5 kHz. However,
of all species studied, T. pumila had best hearing sensitivity at frequencies above 2 kHz. The association between high-pitched sounds and hearing may be caused
by the suprabranchial air-breathing chamber, which, lying close to the hearing and sonic organs, enhances both sound perception
and emission at its resonant frequency.
Accepted: 26 November 1997 相似文献
5.
Marco Lugli 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2010,196(6):439-451
The habitat ambient noise may exert an important selective pressure on frequencies used in acoustic communication by animals.
A previous study demonstrated the presence of a match between the low-frequency quiet region of the stream ambient noise (termed
‘quiet window’) and the main frequencies used for sound production and hearing by two stream gobies (Padogobius bonelli, Gobius nigricans). The present study examines the spectral features of ambient noise in very shallow freshwater, brackish and marine habitats
and correlates them to the range of dominant frequencies of sounds used by nine species of Mediterranean gobies reproducing
in these environments. Ambient noise spectra of these habitats featured a low-frequency quiet window centered at 100 Hz (stream,
sandy/rocky sea shore), or at 200 Hz (spring, brackish lagoon). The analysis of the ambient noise/sound spectrum relationships
showed the sound frequencies matched the frequency band of the quiet window in the ambient noise typical of their own habitat.
Analogous ambient noise/sound frequency relationships were observed in other shallow-water teleosts living in similar underwater
environments. Conclusions may be relevant to the understanding of evolution of fish acoustic communication and hearing. 相似文献
6.
Andrea Megela Simmons Victoria Flores 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2012,198(4):253-266
In their shallow-water habitats, bullfrog (Rana catesbeiana) tadpoles are exposed to both underwater and airborne sources of acoustic stimulation. We probed the representation of underwater
particle motion throughout the tadpole’s dorsal medulla to determine its spatial extent over larval life. Using neurobiotin-filled
micropipettes, we recorded neural activity to z-axis particle motion (frequencies of 40–200 Hz) in the medial vestibular nucleus, lateral vestibular nucleus, dorsal medullary
nucleus (DMN), and along the dorsal arcuate pathway. Sensitivity was comparable in the medial and lateral vestibular nuclei,
with estimated thresholds between 0.016 and 12.5 μm displacement. Neither best responding frequency nor estimated threshold
varied significantly over larval stage. Transport of neurobiotin from active recording sites was also stable over development.
The DMN responded poorly to z-axis particle motion, but did respond to low-frequency pressure stimulation. These data suggest that particle motion is represented
widely and stably in the tadpole’s vestibular medulla. This is in marked contrast to the representation of pressure stimulation
in the auditory midbrain, where a transient “deaf period” of non-responsiveness and decreased connectivity occurs immediately
prior to metamorphic climax. We suggest that, in bullfrogs, sensitivity to particle motion and to pressure follows different
developmental trajectories. 相似文献
7.
G. Kämper V. Y. Vedenina 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(6):715-724
Interneurons in the cercal sensory system of crickets respond in a cell-specific manner if the cercal hair sensilla are stimulated
by air-particle oscillations at frequencies below about 2000 Hz. We investigated the filter properties of several of these
interneurons, and tested the effect of stimulus intensity (typically 0.3–50 mm s−1 peak-to-peak air-particle velocity) on the frequency response in the range 5–600 Hz. We focus on three interneurons (the
lateral and medial giant interneurons and interneuron 9-3a) of Acheta domesticus which are characterized by a relatively high sensitivity above ca. 50–200 Hz. The responses of the medial giant interneuron
usually increase monotonically with frequency and intensity. Interneuron 9-3a and the lateral giant interneuron exhibit saturation
or response decrement at high frequencies and intensities. The lateral giant interneuron has an additional peak of sensitivity
below about 40 Hz. Small individual variations in the relative locations of the two response areas of this interneuron within
the frequency-intensity field are responsible for a large variability obtained if frequency-response curves are determined
for particular intensities. Stimulus frequency does not affect the principal directional preferences of the three interneurons.
Nevertheless, if tested individually, the lateral giant interneuron and interneuron 9-3a exhibit small changes of directional
tuning.
Accepted: 12 November 1997 相似文献
8.
Karen P. Maruska Timothy C. Tricas 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(11):1071-1088
The fish auditory system encodes important acoustic stimuli used in social communication, but few studies have examined response
properties of central auditory neurons to natural signals. We determined the features and responses of single hindbrain and
midbrain auditory neurons to tone bursts and playbacks of conspecific sounds in the soniferous damselfish, Abudefduf abdominalis. Most auditory neurons were either silent or had slow irregular resting discharge rates <20 spikes s−1. Average best frequency for neurons to tone stimuli was ~130 Hz but ranged from 80 to 400 Hz with strong phase-locking. This
low-frequency sensitivity matches the frequency band of natural sounds. Auditory neurons were also modulated by playbacks
of conspecific sounds with thresholds similar to 100 Hz tones, but these thresholds were lower than that of tones at other
test frequencies. Thresholds of neurons to natural sounds were lower in the midbrain than the hindbrain. This is the first
study to compare response properties of auditory neurons to both simple tones and complex stimuli in the brain of a recently
derived soniferous perciform that lacks accessory auditory structures. These data demonstrate that the auditory fish brain
is most sensitive to the frequency and temporal components of natural pulsed sounds that provide important signals for conspecific
communication. 相似文献
9.
Xuguang Zhang Hongyi Guo Jia Chen Jiakun Song Kaida Xu Jun Lin Shouyu Zhang 《Zeitschrift fur angewandte Ichthyologie》2021,37(4):514-522
Environmental assessments of underwater noise on marine species must be based on species-specific hearing abilities. This study was to assess the potential impact of underwater noise from the East China Sea Bridge wind farm on the acoustic communication of the marbled rockfish. Here, the 1/3 octave frequency band of underwater noise was 125 Hz with the level range of 78–96 dB re 1 μPa, recorded at distances between 15-20m from the foundation at wind speed of 3–5 m/s. Auditory evoked potential (AEP) and passive acoustic techniques were used to determine the hearing abilities and sound production of the fish. The resultes showed the lowest auditory threshold of Sebastiscus marmoratus was 70 dB at 150 Hz matching the disturbance sound ranging 140–180 Hz, which indicating the acoustic communication used in this species. However, the frequency and level of turbine underwater noise overlapped the auditory sensitivity and vocalization of Sebastiscus marmoratus. The wind turbine noise could be detected by fish and may have a masking effect on their acoustic communication. This result can be applied for further to the assessent of fish species released into offshore wind farm marine ranch. 相似文献
10.
A. P. Purgue P. M. Narins 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(5):481-488
The frog inner ear consists of a complex of fluid-filled membranous sacs and canals containing eight distinct clusters of
sensory hair cells. In this study we attempt to delineate the potential pathways for acoustic energy flow toward two of these
clusters located within the amphibian papilla and the basilar papilla. Detailed morphological measurements of the periotic
canal based on internal casts of the inner ear in the bullfrog (Rana catesbeiana) revealed that it is divided into a wide, tapered section and a narrower section comprised of two branches – one short and
blind projecting into the endolymphatic space and another longer, terminating in the round window. Additionally, we used laser
Doppler velocimetry to record the velocity responses of the contact membranes of the amphibian papilla and basilar papilla.
We found that the acoustic energy flow through these two structures is frequency dependent such that the amphibian papilla
contact membrane displays a peak velocity amplitude at frequencies less than 500 Hz, whereas the basilar papilla contact membrane
velocity response exhibits a maximum above 1100 Hz. Our data advocate a mechanical substrate underlying the frequency segregation
in the auditory nerve fibers innervating the amphibian papilla and the basilar papilla.
Accepted: 9 March 2000 相似文献
11.
James A. Simmons Andrea Megela Simmons 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(5):585-594
Widely divergent vertebrates share a common central temporal mechanism for representing periodicities of acoustic waveform
events. In the auditory nerve, periodicities corresponding to frequencies or rates from about 10 Hz to over 1,000 Hz are extracted
from pure tones, from low-frequency complex sounds (e.g., 1st harmonic in bullfrog calls), from mid-frequency sounds with
low-frequency modulations (e.g., amplitude modulation rates in cat vocalizations), and from time intervals between high-frequency
transients (e.g., pulse-echo delay in bat sonar). Time locking of neuronal responses to periodicities from about 50 ms down
to 4 ms or less (about 20–300 Hz) is preserved in the auditory midbrain, where responses are dispersed across many neurons
with different onset latencies from 4–5 to 20–50 ms. Midbrain latency distributions are wide enough to encompass two or more
repetitions of successive acoustic events, so that responses to multiple, successive periods are ongoing simultaneously in
different midbrain neurons. These latencies have a previously unnoticed periodic temporal pattern that determines the specific
times for the dispersed on-responses. 相似文献
12.
Recent works on the response of barrel neurons to periodic deflections of the rat vibrissae have shown that the stimulus velocity
is encoded in the corti cal spike rate (Pinto et al., Journal of Neurophysiology, 83(3), 1158–1166, 2000; Arabzadeh et al., Journal of Neuroscience, 23(27), 9146–9154, 2003). Other studies have reported that repetitive pulse stimulation produces band-pass filtering of the barrel response rate
centered around 7–10 Hz (Garabedian et al., Journal of Neurophysiology, 90, 1379–1391, 2003) whereas sinusoidal stimulation gives an increasing rate up to 350 Hz (Arabzadeh et al., Journal of Neuroscience, 23(27), 9146–9154, 2003). To explore the mechanisms
underlying these results we propose a simple computational model consisting in an ensemble of cells in the ventro-posterior
medial thalamic nucleus (VPm) encoding the stimulus velocity in the temporal profile of their response, connected to a single
barrel cell through synapses showing short-term depression. With sinusoidal stimulation, encoding the velocity in VPm facilitates
the response as the stimulus frequency increases and it causes the velocity to be encoded in the cortical rate in the frequency
range 20–100 Hz. Synaptic depression does not suppress the response with sinusoidal stimulation but it produces a band-pass
behavior using repetitive pulses. We also found that the passive properties of the cell membrane eventually suppress the response
to sinusoidal stimulation at high frequencies, something not observed experimentally. We argue that network effects not included
here must be important in sustaining the response at those frequencies.
相似文献
Jaime de la RochaEmail: |
13.
Joachim Mogdans Ines E. Nauroth 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(10):959-968
We studied the role of the lateral line system for detection and discrimination of dipole stimuli in the oscar, Astronotus ocellatus (Family Cichlidae), and determined detection thresholds in still water and frequency discrimination capabilities in still
and turbulent water. Average detection threshold of six animals for a 100-Hz dipole stimulus was 0.0059 μm peak-to-peak water
displacement at the surface of the fish. After inactivation of the neuromast receptor organs of the lateral line system with
the antibiotic streptomycin, dipole detection was reduced, but recovered within 2–4 weeks. This suggests that the oscar relied
strongly on hydrodynamic information received by the lateral line system. Five oscars learned to discriminate a 100-Hz stimulus
from 70 Hz and lower frequencies. When turbulence was introduced into the experimental tank, fish were still able to discriminate
100 Hz from frequencies 70 Hz and lower indicating that frequency discrimination mediated by the lateral line system was not
reduced in turbulent water. 相似文献
14.
Lan Ding Hong-Wei Jing Tao Wang Jing Li Guo-An Liu 《Journal of Plant Growth Regulation》2010,29(4):419-427
Epinodosin, an ent-kaurane diterpenoid isolated from Isodon japonica var. galaucocalyx, had a biphasic, dose-dependent effect on root growth and a strong inhibitory effect on root hair development in Lactuca sativa L. seedlings. Lower levels of epinodosin (25–100 μM) significantly promoted root growth, but higher concentrations (150–200 μM),
by contrast, had inhibitory effects. In addition, all of the tested concentrations (20–80 μM) inhibited root hair development
of lettuce seedlings in a dose-dependent manner. Further investigations on the underlying mechanism revealed that the promotion
effect of epinodosin (25–100 μM) resulted from increasing the cell length in the mature region and enhancing the mitotic activity
of meristematic cells in lettuce seedling root tips. On the other hand, epinodosin at higher concentrations inhibited root
growth by strongly affecting both the cell length in the mature region and the division of meristematic cells. Comet assay
analysis demonstrated that the decrease of mitotic activity of root meristematic cells was due to DNA damage induced by higher
levels of epinodosin. 相似文献
15.
Auditory and vestibular functions of otolithic organs vary among vertebrate taxa. The saccule has been considered a major hearing organ in many fishes. However, little is known about the auditory role of the lagena in fishes. In this study we analyzed directional and frequency responses from single lagenar fibers of Dormitator latifrons to linear accelerations that simulate underwater acoustic particle motion. Characteristic frequencies of the lagenar fibers fell into two groups: 50 Hz and 80–125 Hz. We observed various temporal response patterns: strong phase-locking, double phase-locking, phase-locked bursting, and non-phase-locked bursting. Some bursting responses have not been previously observed in vertebrate otolithic nerve fibers. Lagenar fibers could respond to accelerations as small as 1.1 mm s–2. Like saccular fibers, lagenar fibers were directionally responsive and decreased directional selectivity with stimulus level. Best response axes of the lagenar fibers clustered around the lagenar longitudinal axis in the horizontal plane, but distributed in a diversity of axes in the mid-sagittal plane, which generally reflect morphological polarizations of hair cells in the lagena. We conclude that the lagena of D. latifrons plays a role in sound localization in elevation, particularly at high stimulus intensities where responses of most saccular fibers are saturated.Abbreviations BRA
best response axis/axes
- BS
best sensitivity
- CF
characteristic frequency
- CV
coefficient of variation
- DI
directionality index
- ISIH
inter-spike interval histogram
- PSTH
peri-stimulus time histogram
- SR
spontaneous rate 相似文献
16.
J. A. Sisneros T. C. Tricas C. A. Luer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,183(1):87-99
This study examined the response properties of skate electrosensory primary afferent neurons of pre-hatch embryo (8–11 weeks),
post-hatch juvenile (1–8 months), and adult (>2 year) clearnose skates (Raja eglanteria) to determine whether encoding of electrosensory information changes with age, and if the electro-sense is adapted to encode
natural bioelectric stimuli across life history stages. During ontogeny, electrosensory primary afferents increase resting
discharge rate, spike regularity, and sensitivity at best frequency. Best frequency was at 1–2 Hz for embryos, showed an upwards
shift to 5 Hz in juveniles, and a downward shift to 2–3 Hz in adults. Encapsulated embryos exhibit ventilatory movements that
are interrupted by a “freeze response”” when presented with weak uniform fields at 0.5 and 1 Hz. This phasic electric stimulus
contains spectral information found in potentials produced by natural fish predators, and therefore indicates that the embryo
electrosense can efficiently mediate predator detection and avoidance. In contrast, reproductively active adult clearnose
skates discharge their electric organs at rates near the peak frequency sensitivity of the adult electrosensory system, which;
facilitates electric communication during social behavior. We suggest that life-history-dependent functions such as these
may shape the evolution of the low-frequency response properties for the elasmobranch electrosensory system.
Accepted: 19 February 1998 相似文献
17.
Günter Kämper Hans-Ulrich Kleindienst 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(2):193-200
1. | Filiform hairs of various lengths on the cerci of adult crickets vibrate in a sound field. These movements were measured with a photodetector for sound frequencies from 10 Hz to 200 Hz in the species Acheta domestica, Gryllus bimaculatus and Phaeophilacris spectrum. |
2. | With low air-particle velocities, the hair shafts were deflected sinusoidally from their resting position, without bending or secondary oscillations (Figs. 2 A, 3 A). At higher velocities (from ca. 80 mm/s peak velocity, depending on the properties of the individual hairs), the shaft struck the cuticular rim of the socket in which the base of the hair is seated (Fig. 2B). This contact was made at an average angular displacement from the resting position of 5.16°±1.0°. |
3. | The best frequencies of the hairs were found to be between 40 Hz and 100 Hz (Fig. 5A). The slope of the amplitude curve for constant peak air-particle velocity at frequencies below the best frequencies was between 0 and 6 dB/octave. Long hairs had smaller slope values than short hairs (Fig. 5C). |
4. | At its best frequency the ratio of maximal tip displacement of a hair to the displacement of the air particles in the sound field was between 0.2 and 2. Only a small number of hairs (2 out of 36) showed tip displacements exceeding twice the air-particle displacement. The values of maximal angular displacement were not correlated to hair length (Fig. 5 B). |
5. | The angular displacement of the hairs was phase shifted with respect to the air-particle velocity by 0° to +45° (phase lead) at sound frequencies around 10 Hz and by -45° to -120° (phase lag) at 200 Hz (Figs. 3C, 4B). At a particular frequency long hairs tended to have larger phase lags than shorter hairs (Fig. 5D). |
18.
Effects and molecular mechanisms of the biological action of weak and extremely weak magnetic fields
V. V. Novikov V. O. Ponomarev G. V. Novikov V. V. Kuvichkin E. V. Yablokova E. E. Fesenko 《Biophysics》2010,55(4):565-572
A number of effects of weak combined (static and alternating) magnetic fields with an alternating component of tens and hundreds
nT at a collinear static field of 42 μT, which is equivalent to the geomagnetic field, have been found: activation of fission
and regeneration of planarians Dugesia tigrina, inhibition of the growth of the Ehrlich ascites carcinoma in mice, stimulation of the production of the tumor necrosis factor
by macrophages, decrease in the protection of chromatin against the action of DNase 1, and enhancement of protein hydrolysis
in systems in vivo and in vitro. The frequency and amplitude ranges for the alternating component of weak combined magnetic
fields have been determined at which it affects various biological systems. Thus, the optimal amplitude at a frequency of
4.4 Hz is 100 nT (effective value); at a frequency of 16.5 Hz, the range of effective amplitudes is broader, 150–300 nT; and
at a frequency of 1 (0.5) Hz, it is 300 nT. The sum of close frequencies (e.g., 16 and 17 Hz) produces a similar biological
effect as the product of the modulating (0.5 Hz) and carrying frequencies (16.5 Hz), which is explained by the ratio A = A
0sinω1
t + A
0sinω2
t = 2A
0sin(ω1 + ω2)t/2cos(ω1–ω2)t/2. The efficiency of magnetic signals with pulsations (the sum of close frequencies) is more pronounced than that of sinusoidal
frequencies. These data may indicate the presence of several receptors of weak magnetic fields in biological systems and,
as a consequence, a higher efficiency of the effect at the simultaneous adjustment to these frequencies by the field. Even
with consideration of these facts, the mechanism of the biological action of weak combined magnetic fields remains still poorly
understood. 相似文献
19.
Mario Penna Nelson A. Velásquez Jaime Bosch 《Biological journal of the Linnean Society. Linnean Society of London》2015,116(1):41-51
The auditory sensitivity in three species of the anuran genus Alytes (Alytidae) was examined to determine patterns of intra‐ and interspecific variation, relating these measurements to behavioural preferences measured in previous studies and to the adaptive and evolutionary significance of this sensory function. The audiograms obtained with multi‐unit recordings in the torus semicircularis of 13 Alytes cisternasii, 10 Alytes obstetricans, and eight Alytes dickhilleni show two regions of enhanced sensitivity, between approximately 100–500 and 1200–2400 Hz, with minimum thresholds at approximately 40 and 45 dB SPL, respectively. The mean and range of the high‐frequency region differed among species, although the sensitivity, measured as minimum thresholds, was similar. The region of high‐frequency sensitivity was centred at approximately the frequency of the advertisement call in A. cisternasii but, in A. obstetricans and A. dickhilleni, was centred at frequencies higher than the conspecific calls. These results contrast with preferences for lower frequencies exhibited by Alytes in female phonotactic and in male evoked vocal responses. Such loose relationships between signals and receivers suggest that the divergence of the sound communication system in Alytes has implied environmental and phylogenetic factors in addition to sexual selection processes. 相似文献
20.
Dali Kang Hongli Zhang Qingqian Zeng Xiaolu Mo Yusheng Wang Depo Yang 《Acta Physiologiae Plantarum》2011,33(3):711-716
Plants in their natural environment are usually affected by mechanical stress because of their sessile growth habit. This
work was aimed at determining the effects of mechanical vibration on the growth rate, physiological indexes, and secondary
metabolite biosynthesis of Camptotheca acuminata calli. In this study, mechanical vibrations of 1–4 Hz in frequency were applied to stimulate the C. acuminata calli; we found that a mechanical vibration of moderate frequency (2 Hz) can clearly promote the growth rate and increase
the soluble protein content and superoxide dismutase (SOD) activity. Under a mechanical vibration of a 2 Hz frequency, camptothecin
(CPT), the main secondary metabolite produced by C. acuminata, was increased by about fourfold compared to the control group, In contrast, the increased accumulation disappears at higher
frequencies. The optimal vibration time for obtaining the highest levels of biomass and CPT was 60 min. This study showed
that there are neutral frequencies and optimal periods of mechanical vibration on C. acuminata calli. 相似文献