Acoustic communication: sound advice from piranhas

An elegant new study has correlated the generation of sound patterns in the red-bellied piranha (Pygocentrus nattereri) with three distinct behaviours.     

Sounds and sound production in fishes

The main information on the sounds and sound production in fishes is reviewed. The present systems of sound classification and specialized sound production in fishes with different taxonomic positions and ecology are described. The anatomy of sound generating organs is analyzed, and the mechanisms of production of different types of sounds (stridulation, drumming, cavitation, and percussion, as well as hydrodynamic, pneumatic, stringed, and respiratory sounds) are discussed. A brief characterization of the acoustic parameters of different sound types is given. Recent data on the anatomy and morphology of the sonic muscles (including their innervation, physiology, sexual dimorphism, and seasonal changes) are reviewed. The dynamics of the development of sound generating organs are described, and their capacity for sound production in the ontogeny of fishes is followed.     

脂鲤目鱼类和"食人鲳"

“食人鲳”是脂鲤目锯鲑脂鲤科锯鲑脂鲤属鱼类的俗称,这类鱼原产南美洲亚马逊河流域,目前已经作为观赏鱼类被引入到包括中国在内的世界上很多国家和地区,而我们对“食人鲳”所属的脂鲤目鱼类还不甚了解。简要地介绍了有关该类群鱼类的分类学及其他一些基本情况,并以“食人鲳”作为代表动物,就锯鲑脂鲤属鱼类的系统学、形态学、生物学信息等进行了较为详细地讨论和介绍。     

Compressive nonlinearity of human hearing in sound spectra discrimination

In the psychophysical experiments reported here, cochlear compression function was derived by comparing on-frequency and off-frequency masking. The signal was rippled spectrum noise. The ripple density discrimination threshold was measured in the ripple phase reversion test. An increase in masker intensity led to a decrease in a resolvable ripple density threshold. The on-frequency masker level at threshold increased proportionally to the signal intensity. The off-frequency masker level at threshold also increased proportionally to the signal at signal intensity levels below 50 dB, whereas at signal levels above 60 dB SPL, the ratio of the masker level at threshold gradient to signal level gradient was 1 : 5 dB/dB, revealing cochlear compression.     

Acoustic communication in two freshwater gobies: the relationship between ambient noise,hearing thresholds and sound spectrum

Two freshwater gobies Padogobius martensii and Gobius nigricans live in shallow (5-70 cm) stony streams, and males of both species produce courtship sounds. A previous study demonstrated high noise levels near waterfalls, a quiet window in the noise around 100 Hz at noisy locations, and extremely short-range propagation of noise and goby signals. To investigate the relationship of this acoustic environment to communication, we determined audiograms for both species and measured parameters of courtship sounds produced in the streams. We also deflated the swimbladder in P. martensii to determine its effect on frequency utilization in sound production and hearing. Both species are maximally sensitive at 100 Hz and produce low-frequency sounds with main energy from 70 to 100-150 Hz. Swimbladder deflation does not affect auditory threshold or dominant frequency of courtship sounds and has no or minor effects on sound amplitude. Therefore, both species utilize frequencies for hearing and sound production that fall within the low-frequency quiet region, and the equivalent relationship between auditory sensitivity and maximum ambient noise levels in both species further suggests that ambient noise shapes hearing sensitivity.     

Continuing to break the sound barrier: genes in hearing

The past year has seen major advances in our understanding of the genes involved in Usher syndrome, as well as the discovery of a myriad of other genes expressed specifically in hair cells. Mouse models continue to be invaluable in illuminating our knowledge of how mutations in genes lead to deafness. The role of mitochondrial genes in the hearing process has also contributed to elucidating the workings of the auditory system.     

Phototaxis inEuglena. VI. Correlations between ATP production by light and phototactic rates

Using DCMU and CCP to specifically affect the photosynthetic system, the kinetics of inhibition of photophosphorylation and phototaxis inEuglena are shown to be the same. In the case of DCMU, measurements of oxygen evolution demonstrate that the delay observed between exposure to inhibitor and maximum effect is not due to the time required for the DCMU to reach its site of action, thus suggesting the presence of an endogenous pool of electron donors which can bypass photosystem II. Placing a culture in darkness causes a cessation of growth and an increase in ATP content per cell, during the same time period in which phototactic activity remains constant. The results are interpreted in terms of the utilization of photosynthetically generated ATP as an energy source for phototactic orientation and a control system which acts to maintain phototactic energy reserves during an extended period of little or no photosynthetic activity.A portion of this work was presented at the Conference on Phototaxis and Photokinesis in Flagellated Cells, University of California, Santa Barbara, August 21–22, 1969.     

Underwater observations of piranhas in western Brazil

Synopsis The behaviour of three piranha species,Serrasalmus marginatus, S. spilopleura, andPygocentrus nattereri, and their prey fishes was studied underwater in the Pantanal region, Mato Grosso, Brazil. General habits, predatory tactics, feeding behaviour, and social interactions while foraging, as well as defensive tactics of prey fishes were observed.S. marginatus is solitary whereas the other two species live in shoals; their agonistic behaviour varies accordingly, the simplest being displayed by the solitary species. Predatory tactics and feeding behaviour also vary:S. spilopleura shows the most varied diet and highly opportunistic feeding strategy, which includes aggressive mimicry. The solitaryS. marginatus, besides fin and scale-eating, occasionally cleans larger individuals ofP. nattereri. Several cichlid species display defensive tactics clearly related to piranha attacks: tail protecting, watching, and confronting the predator are the most commonly observed behaviours. Piranhas seem to strongly influence use of habitat, social structure, and foraging mode of the fish communities.     

Correlations between song acquisition, song production, and plasma levels of testosterone and estradiol in sparrows

Male birdsong is a sexually dimorphic behavior characterized by learned dialects. In a combined study of learning in relation to steroid levels in the plasma, changes in estradiol and testosterone levels were correlated with the timing of the sensitive period for song acquisition and with successive stages in song development. Male swamp sparrows were trained with a changing series of live singing tutors from 26 days to 1 year of age. Song acquisition was concentrated between 26 and 47 days of age (57%). By 85 days of age 71% of acquisition was completed; some occurred as late as 300 days. There were two major periods when testosterone levels were elevated. The first, from 30-80 days, encompassed most of the period of song acquisition. The second, from 260 to at least 360 days of age, coincided with song development. Estradiol levels were elevated from 18 to 170 days of age, encompassing almost all of the period of song acquisition. A marked estradiol peak between 40 and 50 days coincided with a trough in testosterone levels and a hiatus in song acquisition. The strong correlation between the second period of elevated testosterone and song motor development suggests a causal connection, with levels peaking in mid-development and declining during mature song production. Estradiol levels were elevated at the start of the study and remained so during early subsong production, from 30 to 165 days. They then fell to baseline, remaining there throughout the resumption of subsong and plastic song production at 250-326 days. Both estradiol and testosterone are candidates for possibly affecting song acquisition.     

The African cichlid fish Astatotilapia burtoni uses acoustic communication for reproduction: sound production, hearing, and behavioral significance

Sexual reproduction in all animals depends on effective communication between signalers and receivers. Many fish species, especially the African cichlids, are well known for their bright coloration and the importance of visual signaling during courtship and mate choice, but little is known about what role acoustic communication plays during mating and how it contributes to sexual selection in this phenotypically diverse group of vertebrates. Here we examined acoustic communication during reproduction in the social cichlid fish, Astatotilapia burtoni. We characterized the sounds and associated behaviors produced by dominant males during courtship, tested for differences in hearing ability associated with female reproductive state and male social status, and then tested the hypothesis that female mate preference is influenced by male sound production. We show that dominant males produce intentional courtship sounds in close proximity to females, and that sounds are spectrally similar to their hearing abilities. Females were 2-5-fold more sensitive to low frequency sounds in the spectral range of male courtship sounds when they were sexually-receptive compared to during the mouthbrooding parental phase. Hearing thresholds were also negatively correlated with circulating sex-steroid levels in females but positively correlated in males, suggesting a potential role for steroids in reproductive-state auditory plasticity. Behavioral experiments showed that receptive females preferred to affiliate with males that were associated with playback of courtship sounds compared to noise controls, indicating that acoustic information is likely important for female mate choice. These data show for the first time in a Tanganyikan cichlid that acoustic communication is important during reproduction as part of a multimodal signaling repertoire, and that perception of auditory information changes depending on the animal's internal physiological state. Our results highlight the importance of examining non-visual sensory modalities as potential substrates for sexual selection contributing to the incredible phenotypic diversity of African cichlid fishes.     

Correlations between Isonymy Parameters

Several parameters of genetic and anthropological interest are commonly estimated in the analysis of the surnames' distribution in human populations. Among these parameters, the most important for population structure is unbiased Isonymy, equivalent to 4 times the value of F_st, the random component of inbreeding in a group. Fisher's α estimates the wealth of surnames in a group, and Karlin-McGregorv is considered proportional to migration rates. Recently, other parameters like Entropy and Redundance of the surname's distribution were introduced in the analysis and estimated. In the present work, the parameters obtained through isonymy analysis of 759,500 telephone users in 379 Communes of Sicily are correlated with variables such as sample size, population size and density, and number of surnames in the Commune. In Sicily, the parameters or their logarithm are Gammadistributed. It is observed that the number of surnames is strongly correlated with most parameters or with their logarithm, and that it is in turn strongly correlated with sample size.     

Animal bells as symbols: sound and hearing in a Greek island village

This article deals with the cultural construction of sound and hearing in a mountain village in the Greek island of Naxos, in the Cyclades. The analysis is based on the ethnographic presentation and discussion of the cultural meanings and symbolism of animal bells. I further explore the relation of bells and their sound to the issues of social reproduction and the cultural constitution of social order. By focusing on the indigenous conceptualizations of sound and noise and the metaphoric language concerning the sense of hearing, I also consider some wider aspects of sound, sound symbolism, and hearing in this community.     

Correlations between relatives in small populations

Correlations between relatives in small, closed populations can be substantially smaller than predicted by the classical formulas of population genetics. This effect is especially pronounced for relatives whose most recent common ancestor is several generations removed. When the effective population size is small, correlations between even close relatives can be negative. This implies that in small populations conventional estimators of quantitative genetics parameters will be biased and that preferential treatment of close relatives will be less likely to evolve.     

Correlations between cytogenetics and morphology in myelodysplastic syndromes

In order to detect possible relationships between cytogenetic abnormalities and morphologic features in myelodysplastic syndromes (MDS), 48 patients with MDS were investigated. Clonal cytogenetic abnormalities were present in bone marrow cells from 27 patients (56%). The most frequent single anomaly was del (5 q) (10 cases), followed by monosomy 7 (3 cases), trisomy 8 (3 cases) and del (20 q) (2 cases). Complex anomalies were present in 6 patients. Morphologically, according to the French-American-British (FAB) classification: 17 cases were considered as refractory anemia (RA), 17 as RA with excess of blasts (RAEB), 2 as RAEB in transformation, 2 as acquired idiopathic sideroblastic anemia and 10 as chronic myelomonocytic leukemia. With regard to the FAB classification, del (5 q) was often associated with RA and complex cytogenetic anomalies with RAEB. When myelodysplasia was studied in individual myeloid lineages, del (5 q) was associated with hypolobulated megakaryocytes, monosomy 7 with micromegakaryocytes and complex chromosomal anomalies with the association of two or more features of dysmegakaryocytopoiesis. Del (11 q) was associated with increased iron storage and del (20 q) with marked dyserythropoiesis. No correlation was observed between cytogenetic anomalies and features of dysgranulocytopoiesis.     

Measuring the efficiency of sound production

Sound production efficiency is a complex phenotypic trait that incorporates biochemical and mechanical events beginning with substrate oxidation and ending with the radiation of sound. Its accurate measurement is significant in understanding the mechanisms and energetics underlying acoustic signaling and sexual selection. I show that in the short-tailed cricket Anurogryllus arboreus Walker, acoustic performance is apparently the same in acoustic free fields and in the reverberant conditions of a respirometry chamber. I present three methods for simultaneous and nearly simultaneous determination of calling metabolic rate and acoustic power output. The new methods yielded metabolic rates 3%-6% lower than matched controls using traditional flow-through respirometry (mean=8.1 mW); however, none of theses differences were statistically significant. I also evaluate four methods for determining the efficiency of sound production. The means of an individual's efficiencies calculated using these methods vary between 0.50% and 0.60%, with no statistically significant differences between the methods. I conclude with a critical evaluation of these techniques.     

Innate sound production in the cichlid Oreochromis niloticus

The mouthbrooding cichlid Oreochromis niloticus is one of the world's best-studied fish and is raised extensively for aquaculture. Although it is a common behavioural model, its acoustic communication has been neglected. Because of extensive parental care, the species is a good candidate for vocal learning. In male O. niloticus , we investigated for the first time sound production in agonistic interactions during nest construction. Males produce short-duration (250–400 ms), often double-pulse sounds. Most energy is below 200 Hz and includes three main low-frequency peaks although energy extends beyond 1 kHz. Males (separated as eggs and raised in isolation) produce similar sounds in the same context as parental fish, indicating that the ability to produce sounds and the basic properties of the sounds are innate.     

Correlations between Income Inequality and Antimicrobial Resistance

Objectives

The aim of this study is to investigate if correlations exist between income inequality and antimicrobial resistance. This study’s hypothesis is that income inequality at the national level is positively correlated with antimicrobial resistance within developed countries.

Data collection and analysis

Income inequality data were obtained from the Standardized World Income Inequality Database. Antimicrobial resistance data were obtained from the European antimicrobial Resistance Surveillance Network and outpatient antimicrobial consumption data, measured by Defined daily Doses per 1000 inhabitants per day, from the European Surveillance of antimicrobial Consumption group. Spearman’s correlation coefficient (r) defined strengths of correlations of: > 0.8 as strong, > 0.5 as moderate and > 0.2 as weak. Confidence intervals and p values were defined for all r values. Correlations were calculated for the time period 2003-10, for 15 European countries.

Results

Income inequality and antimicrobial resistance correlations which were moderate or strong, with 95% confidence intervals > 0, included the following. Enterococcus faecalis resistance to aminopenicillins, vancomycin and high level gentamicin was moderately associated with income inequality (r= ≥0.54 for all three antimicrobials). Escherichia coli resistance to aminoglycosides, aminopenicillins, third generation cephalosporins and fluoroquinolones was moderately-strongly associated with income inequality (r= ≥0.7 for all four antimicrobials). Klebsiella pneumoniae resistance to third generation cephalosporins, aminoglycosides and fluoroquinolones was moderately associated with income inequality (r= ≥0.5 for all three antimicrobials). Staphylococcus aureus methicillin resistance and income inequality were strongly associated (r=0.87).

Conclusion

As income inequality increases in European countries so do the rates of antimicrobial resistance for bacteria including E. faecalis, E. coli, K. pneumoniae and S. aureus. Further studies are needed to confirm these findings outside Europe and investigate the processes that could causally link income inequality and antimicrobial resistance.     

Correlations between live and stillbirth outcomes in twin pairs

A relationship has been proposed to exist between individual outcomes (live or stillbirth) of twins in the same set. Here, we analyze this association between live births and stillbirths among individuals in different twin pairs. When national birth registers are analyzed, individuals in opposite-sex twin sets can be identified and the correlation between individual outcomes estimated. However, full information about the individuals in same-sex twin sets is not, as a rule, available, and consequently, correlation coefficients cannot be estimated, but upper and lower limits of the correlation coefficients can be obtained. The methods introduced here were applied to data from Sweden (1869-1967), the Aland Islands (Finland) (1750-1949), the Kingdom of Saxony (1881-1900), and England and Wales (1940-2003). Comparisons between the correlation coefficients among opposite-sex twins and the lower bound (minimum) of correlation coefficients among same-sex twins indicate that in all populations studied a stronger association exists between twins in same-sex rather than opposite-sex twin sets or pairs. For opposite-sex twin sets no general association between the correlation coefficient and the stillbirth rate was identified.