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.     

Disaptation and recovery in the evolution of Antarctic fishes

The radiation of notothenioid fishes provides an excellent system to explore issues of evolution and adaptation. Most studies emphasize adaptation to the extreme Antarctic environment; however, recent work provides cogent examples of disaptation or evolutionary loss of function. The nature and extent of regressive change is revealed by subsequent adaptive recovery. Ancestral notothenioids were benthic but some became secondarily pelagic through the retention of larval characters. Paedomorphosis has produced detrimental changes in lateral-line sensory systems that have been made good by compensatory adaptation. In the icefish family, compensatory adaptation has followed the loss of the oxygen-binding pigments haemoglobin and myoglobin.     

Acoustic communication in spring peepers

Summary In the previous study (Wilczynski et al. 1984) we found that neurons in the auditory nerve of female spring peepers (Hyla crucifer) are tuned to frequencies in the male advertisement call, whereas auditory units in male peepers are mismatched in spectral sensitivity to their call. We investigated, in the present report, behavioral consequences of this sexual dimorphism in auditory sensitivity. Call amplitude, rate of call attenuation with environmental transmission, and the amplitude of ambient noise were measured and used to compute the active space of this signal for males and females. The effect of calling height upon active space was considered. Measurements of active space were compared with intermale distances within breeding choruses.Results indicate that active space of the advertisement call for females is as much as 6 times greater than that for males, and varies directly with the height above ground from which males call. Observed maximum intermale distances correspond closely to the active space of the call for this sex. This suggests that males space themselves so that the amplitude of a neighbor's calls approximates their auditory neural threshold to call frequencies. By this proximal mechanism, peepers maximize intermale distance but ensure that they remain within a chorus.Abbreviation dB SPL decibels sound pressure levelre: 20 Pa     

The evolution of sex-change mechanisms in fishes

Synopsis Five distinct sex-change mechanisms are identified among sequentially hermaphroditic fishes based on socio-ecological characteristics. The primary determinants of the sex-change mechanisms appear to be social organization and mating system, which in turn depend on resource distribution in space and time. The ability of a single individual to control all mating in the social unit, which is related to the size of the social unit, differentiates three suppression mechanisms from two induction mechanisms. Sex-change suppression, which is characteristic of species with small group size and rigid dominance hierarchies, refers to inevitable sex change in the absence of group dominance. Ability to migrate between resource patches differentiates protogynous suppression (e.g. inLabroides dimidiatus) from protandrous suppression (e.g. inAmphiprion spp.). Early sex change appears to have evolved from protogynous suppression under special conditions involving the loss of mating control by a single dominant individual in certain species (e.g.Centropyge spp. ). Sex-change induction, which is characteristic of species with large social groups lacking rigid dominance hierarchies, refers to the requirement that sex change must be induced by specific characteristics of (or changes in) the social group, regardless of dominance status. Ability to distinguish sex, or its importance, differentiates sex-ratio induction (e.g.Anthias squamipinnis) from size-ratio induction (e.g.Thalassoma spp.). Alternative models account for the possibility that all cases of sex change require stimulation from smaller conspecifics (universal induction-inhibition model) or that all fish have the genetic capacity to switch mechanisms, depending on changing ecological conditions and resulting changes in mating system (behavioral-scaling model). Neurophysiological models suggest that induction mechanisms, which require at least two categories of environmental stimuli, may have evolved from the simpler suppression mechanisms, which require only one kind of input from the environment.     

Social drive and the evolution of primate hearing

The structure and function of primate communication have attracted much attention, and vocal signals, in particular, have been studied in detail. As a general rule, larger social groups emit more types of vocal signals, including those conveying the presence of specific types of predators. The adaptive advantages of receiving and responding to alarm calls are expected to exert a selective pressure on the auditory system. Yet, the comparative biology of primate hearing is limited to select species, and little attention has been paid to the effects of social and vocal complexity on hearing. Here, we use the auditory brainstem response method to generate the largest number of standardized audiograms available for any primate radiation. We compared the auditory sensitivities of 11 strepsirrhine species with and without independent contrasts and show that social complexity explains a significant amount of variation in two audiometric parameters-overall sensitivity and high-frequency limit. We verified the generality of this latter result by augmenting our analysis with published data from nine species spanning the primate order. To account for these findings, we develop and test a model of social drive. We hypothesize that social complexity has favoured enhanced hearing sensitivities, especially at higher frequencies.     

Thermal energy and the rate of genetic evolution in marine fishes

Slower genetic evolution in microbial thermophiles has been attributed to internal mutation control mechanisms in very high temperatures, whereas the tempo of plant microevolution has been positively correlated to ambient thermal conditions. Here, using a global dataset of 136 teleost fish species, contrasting warm and cool water species, and controlling for any differences between species in mutation control mechanisms, we found mitochondrial genetic evolution was 1.61 times faster in warm water species. These results suggest that temperature-mediated reduction in mutation rate is only important in extreme thermal regimes.     

Life-history correlates of the evolution of live bearing in fishes

Selection for live bearing is thought to occur when the benefits of increasing offspring survival exceed the costs of reduced fecundity, mobility and the increased metabolic demands of carrying offspring throughout development. We present evidence that live bearing has evolved from egg laying 12 times in teleost (bony) fishes, bringing the total number of transitions to 21 to 22 times in all fishes, including elasmobranchs (sharks and rays). Live bearers produce larger offspring than egg layers in all of 13 independent comparisons for which data were available. However, contrary to our expectation there has not been a consistent reduction in fecundity; live bearers have fewer offspring in seven out of the 11 available comparisons. It was predicted that live bearers would have a larger body size, as this facilitates accommodation of developing offspring. This prediction was upheld in 14 out of 20 comparisons. However, this trend was driven by elasmobranchs, with large live bearers in seven out of eight comparisons. Thus, while the evolution of live bearing in elasmobranchs is correlated with predicted increases in offspring size and adult size, teleost live bearers do not have such a consistent suite of life-history correlates. This suggests that constraints or selection pressures on associated life histories may differ in live-bearing elasmobranchs and teleost fishes.     

Acoustic detection and communication by decapod crustaceans

This paper reviews behavioral, physiological, anatomical, and ecological aspects of sound and vibration detection by decapod crustaceans. Our intent is to demonstrate that despite very limited work in this area in the past 20 years, evidence suggests that at least some decapod crustaceans are able to detect and use sounds in ways that parallel detection and processing mechanisms in aquatic and terrestrial vertebrates. Some aquatic decapod crustaceans produce sounds, and many are able to detect substrate vibration at sensitivities sufficient to tell of the proximity of mates, competitors, or predators. Some semi-terrestrial crabs produce and use sounds for communication. These species detect acoustic stimuli as either air- or substrate-borne energies, socially interact in acoustic "choruses," and probably use "calls" to attract mates.     

The evolution of microsatellite loci in salmonid fishes

In ten species of salmonid fishes, sequences of five microsatellite loci were determined. Considerable differences in the structure of the same microsatellites in different species were found. It was demonstrated that the evolution of microsatellites was a complex process, including changes in the copy number, point mutations, and extended deletions and insertions, leading either to the formation of microsatellites or to their loss.     

Complex evolution of vitellogenin genes in salmonid fishes

Vitellogenins (Vtg) are usually encoded by small multigene families containing up to six genes. With 20 tandemly arranged genes, the rainbow trout ( Oncorhynchus mykiss) is an exception to this rule. PCR amplification, cloning and sequence analysis of Vtg genes in other salmonid species revealed the existence of two paralogous gene clusters, designated Vtg-A and Vtg-B. Southern hybridization showed that the number of genes varies from 2 to 30 copies from one species to another, as well as between the two gene clusters. All Coregonus, Thymallus, Salmo and Salvelinus species studied have both gene clusters, while Oncorhynchus species possess only the Vtg-A locus. Phylogenetic trees constructed from Vtg sequences revealed conflicting nodes with the consensus tree based on morphological and anatomical data. Vtg sequences support the grouping ( Salmo, ( Salvelinus, Oncorhynchus)) instead of the accepted consensus ( Salvelinus, ( Salmo, Oncorhynchus)). Structural data on gene organization also support the contention that Salvelinus and Oncorhynchus are sister taxa. Evolutionary implications for the Vtg gene clusters in salmonids are discussed.     

Color and communication in the dreams of hearing and deaf persons.

Research suggests that the experiences recollected from the dreams of persons who are deaf or who have hearing loss reflect their personal background and circumstances. However, this literature also indicated that few studies have surveyed the occurrence of color and communication styles. Individual differences in the perception of color and affect were especially noted. These differences appeared dependent upon whether the impairment was congenital or acquired. In this study, 24 deaf persons and a person with hearing loss who use American Sign Language (ASL) were compared to a sample of hearing persons regarding colors and communication occurring in their dreams. Both groups were found to communicate in dreams as they do in life, deaf persons and person with hearing loss by signing, and hearing persons by speech. The deaf persons and a person with hearing loss experienced more color and more vividness, and the time of onset for a hearing impairment showed differences among persons with hearing loss. The findings also suggest that utilizing dreams as therapeutic material when treating persons with hearing loss and nonimpaired persons may have clinical utility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular evolution of haemoglobins of polar fishes

The Arctic and the Antarctic differ by age and isolation of the respective marine faunas. Antarctic fish are highly stenothermal, in response to stable water temperatures, whereas the Arctic ones are exposed to seasonal and latitudinal temperature variations. The knowledge of the mechanisms of phenotypic response to cold exposure in species of both polar habitats offers fundamental insights into the nature of environmental adaptation. In the process of cold adaptation, the evolutionary trend of Antarctic fish has led to unique specialisations, including modification of haematological characteristics, e.g. decreased amounts and multiplicity of haemoglobins.Unlike Antarctic Notothenioidei, Arctic teleosts have high haemoglobin multiplicity. Although the presence of functionally and structurally distinct haemoglobins is a plesiomorphic condition for many perciform-like fishes, it seems that the oxygen-transport system of teleost fish in the Arctic region has been adjusted to temperature differences and fluctuations of Arctic waters, much larger than in the Antarctic. The amino-acid sequences used to gain insight into the evolution history of α and β globins of polar fish have clearly shown that Antarctic and Arctic globins have different phylogenies, leading to the hypothesis that the selective pressure of environment stability allows the phylogenetic signal to be maintained in the Antarctic sequences, whereas environmental variability would tend to disrupt this signal in Arctic sequences.     

Functional design and evolution of the pharyngeal jaw apparatus in euteleostean fishes

Functional and structural patterns in the pharyngeal jaw apparatus of euteleostean fishes are described and analysed as a case study of the transformation of a complex biological design. The sequential acquisition of structural novelties in the pharyngeal apparatus is considered in relation to both current hypotheses of euteleostean phylogeny and patterns of pharyngeal jaw function. Several euteleostean clades are corroborated as being monophyletic, and morphologically conservative features of the pharyngeal jaw apparatus are recognized. Functional analysis, using cinematography and electromyography, reveals four distinct patterns of muscle activity during feeding in primitive euteleosts (Esox) and in derived euteleostean fishes(Perca, Micropterus, Ambloplites, Pomoxis). The initial strike, buccal manipulation, pharyngeal manipulation, and the pharyngeal transport of prey into the oesophagus all involve unique muscle activity patterns that must be distinguished in analyses of pharyngeal jaw function. During pharyngeal transport, the upper and lower pharyngeal jaws are simultaneously protracted and retracted by the action of dorsal and ventral musculoskeletal gill arch couplings. The levator externus four and retractor dorsalis muscles, anatomical antagonists, overlap for 70–90°of their activity period. Levatores externi one and two are the main protractors of the upper pharyngeal jaws in the acanthopterygian fishes studied. The major features of pharyngeal jaw movement in primitive euteleosts are retained in many derived clades in spite of a dramatic structural reorganization of the pharyngeal region. Homologous muscles have radically changed their relative activity periods while pharyngeal jaw kinematics have been modified relatively little. Patterns of transformation of activity may thus bear little direct relationship to the sequence of structural modification in the evolution of complex designs. Overall function of a structural system may be maintained, however, through co-ordinated modifications of the timing of muscle activity and anatomical reorientation of the musculoskeletal system. Deeper understanding of the principles underlying the origin and transformation of functional design in vertebrates awaits further information on the acquisition of both structural and functional novelties at successive hierarchical levels within monophyietic clades. This is suggested as a key goal of future research in functional and evolutionary morphology.     

Gonad development in Midas cichlids and the evolution of sex change in fishes

Some fishes mature and function as one sex and later transform to the other sex in response to social interactions. Previous evidence suggested that a change in developmental timing may be involved in the evolution of adult sex change in fishes. The most recent support for this idea came from reports that sex in the Midas cichlid, Amphilophus citrinellus, was determined by social conditions experienced at the juvenile stage. Differentiation as a male was reported to be dependent on large body size relative to group-mates, and thought to be mediated through aggressive interactions. Here I demonstrate that socially controlled sex determination does not occur as was originally reported. Previously, I found that sex was not associated with body size in juveniles either in nature or in captivity. Similarly, I found no association between aggressive behavior and sex in juveniles. I later demonstrated that socially controlled sex determination does not typically occur in the Midas cichlid and closely related species and supported an alternative mechanism to explain large body size in adult males. Finally, in the current study I analyze gonad histology of fish from the same population used by the original authors and lay to rest the idea of socially controlled sex determination in this species. Recent observations of socially controlled sex determination in juveniles of species that typically change sex at the adult stage are examples of phenotypic plasticity, not genetic variation. Therefore, juvenile socially controlled sex determination does not support a theory that a change in developmental timing is involved in the evolution of adult sex change in fishes.