Multiple sexual ornaments in satin bowerbirds: ultraviolet plumage and bowers signal different aspects of male quality

Much attention has been devoted to understanding the evolutionof elaborate male ornaments and how they may signal male quality.However, the evolution of multicomponent sexual signals remainspoorly understood, and past research on this type of signalinghas been largely theoretical. Satin bowerbirds, Ptilonorhynchusviolaceus, are polygynous, are sexually dichromatic, and constructsexually selected display structures (bowers): a model systemfor investigating the evolution and signal function of multiplesexual signals. We studied the interrelationship between bowerfeatures, plumage coloration, and indicators of male qualityin this species. To do this, we located the bowers of male satinbowerbirds in rainforest in Queensland, Australia, and quantifiedbower quality. We captured the male bower owners and used reflectancespectrometry to objectively measure the plumage coloration ofseveral body regions. We measured various indicators of malehealth and condition, including the intensity of infection fromectoparasites and blood parasites. Bower quality and male ultravioletplumage coloration were significantly correlated. By using multipleregression analyses, we show that bower quality predicts ectoparasiteload and body size, whereas ultraviolet plumage coloration predictsthe intensity of infection from blood parasites, feather growthrate, and body size. Our findings support the multiple messageshypothesis of multicomponent signals: Female satin bowerbirdsshould assess both male and bower features to choose the highestquality mates.     

Habitat acoustics and primate communication

The acoustic characteristics of three tropical habitats were investigated to determine how they might constrain the structure of primate signals. Ambient noise was measured, along with signal attenuation and aspects of signal degradation (reverberation, amplitude fluctuations, and pulse train modulation depth). These measures allowed estimation of the effects of habitat acoustics on the distances over which calls would be audible (the “active space”) and over which primates could reliably transmit amplitude-modulated or pulse-coded information.     

Echolocation calls in Central American emballonurid bats: signal design and call frequency alternation

In southern Central America, 10 species of emballonurid bats occur, which are all aerial insectivores: some hunt flying insects preferably away from vegetation in open space, others hunt in edge space near vegetation and one species forages mainly over water. We present a search call design of each species and link signal structure to foraging habitat. All emballonurid bats use a similar type of echolocation call that consists of a central, narrowband component and one or two short, frequency-modulated sweeps. All calls are multi-harmonic, generally with most energy concentrated in the second harmonic. The design of search calls is closely related to habitat type, in particular to distance of clutter. Emballonurid bats foraging in edge space near vegetation and over water used higher frequencies, shorter call durations and shorter pulse intervals compared with species mostly hunting in open, uncluttered habitats. Peak frequency correlated negatively with body size. Regular frequency alternation between subsequent calls was typical in the search sequences of four out of 10 species. We discuss several hypotheses regarding the possible role of this frequency alternation, including species identification and partitioning of acoustic channels. Furthermore, we propose a model of how frequency alternation could increase the maximum detection distance of obstacles by marking search calls with different frequencies.     

Snipe taxonomy based on vocal and non-vocal sound displays: the South American Snipe is two species

We analysed breeding sounds of the two subspecies of South American Snipe Gallinago paraguaiae paraguaiae and Gallinago paraguaiae magellanica to determine whether they might be different species: loud vocalizations given on the ground, and the tail-generated Winnow given in aerial display. Sounds of the two taxa differ qualitatively and quantitatively. Both taxa utter two types of ground call. In G. p. paraguaiae, the calls are bouts of identical sound elements repeated rhythmically and slowly (about five elements per second (Hz)) or rapidly (about 11 Hz). One call of G. p. magellanica is qualitatively similar to those of G. p. paraguaiae but sound elements are repeated more slowly (about 3 Hz). However, its other call type differs strikingly: it is a bout of rhythmically repeated sound couplets, each containing two kinds of sound element. The Winnow of G. p. paraguaiae is a series of sound elements that gradually increase in duration and energy; by contrast, that of G. p. magellanica has two or more kinds of sound element that roughly alternate and are repeated as sets, imparting a stuttering quality. Sounds of the related Puna Snipe (Gallinago andina) resemble but differ quantitatively from those of G. p. paraguaiae. Differences in breeding sounds of G. p. paraguaiae and G. p. magellanica are strong and hold throughout their geographical range. Therefore we suggest that the two taxa be considered different species: G. paraguaiae east of the Andes in much of South America except Patagonia, and G. magellanica in central and southern Chile, Argentina east of the Andes across Patagonia, and Falklands/Malvinas.     

Characterization and localization of D1 dopamine receptors in the sexually dimorphic vocal control nucleus,area X,and the basal ganglia of european starlings

D1 dopamine receptors were pharmacologically characterized and localized by quantitative autoradiography in the basal ganglia of male and female European starlings (Sturnus vulgaris). The D1 selective antagonist SCH 23390 was used to label this receptor subtype. Starlings are songbirds and possess a neural circuit implicated in the learning and production of song. This circuit includes a sexually dimorphic nucleus, area X, that is a subregion of the parolfactory lobe of the basal ganglia and is known from work on zebra finches to receive dopaminergic input from the area ventralis of Tsai. We focused our investigation on the D1-like receptor subtype because they are abundant in the basal ganglia. Competition studies indicate that a variety of dopaminergic ligands compete with [³H] SCH 23390 for the binding site in an order of potency characteristic of a D1-like receptor. Autoradiographic studies of the basal ganglia revealed high D1 receptor densities in the avian homologues of the caudate-putamen and relatively low-receptor densities were observed in the avian homologue of the globus pallidus. In male starlings, area X could be reliably discerned on the autoradiograms by the higher density of D1 receptors compared to the surrounding parolfactory lobe (LPO). This was also true for females, though nt as reliably as in males. When we compared the mean D1 receptor density in area X for males and females we did not find a significant sex difference. However, we also analyzed the data by comparing sex differences in the degree to which area X has a higher receptor density in comparison with the surrounding LPO. When we normalized D1 receptor density in area X relative to the LPO, we did find a significant sex difference. This sex difference in relative receptor density represents another neural sex difference in the song circuit that may mediate sex differences in the learning and production of song in starlings and other songbirds. 1994 John Wiley & Sons, Inc.     

Call degradation in diploid and tetraploid green toads

According to the 'environmental selection' hypothesis, the physical characteristics of environments influence the evolution of long-range acoustic signals by favouring those properties that decrease sound attenuation and distortion with distance. Different environments could favour different acoustic properties and therefore contribute to the intra- and interspecific variation of calls. In the present paper, we investigate whether this hypothesis could explain the differences between the advertisement calls of three taxa of central-Asian green toads: lowland diploids, highland tetraploids and lowland tetraploids. The pattern of propagation of 12 natural calls (four for each taxon) was analysed in nine localities of Kyrgyzstan and Kazakstan. We broadcast the calls and recorded them along a trasect at distances of 2, 4, 8, 16, and 32 m from the speaker, to estimate sound attenuation and propagation. Attenuation was quantified from the oscillogram (by directly calculating the SPL of calls) and from the power spectrum (by measuring the relative amplitude of the fundamental frequency) , whereas degradation was estimated by cross-correlating spectrograms of the same call at different distances. Results show that: (1) the pattern of sound propagation significantly differs among localities in relation to the different vegetation and environmental noise; (2) in most localities, call attenuation and degradation differ significantly among the three taxa ; (3) such differences are not consistent to those expected under the hypothesis of environmental selection: independent of altitude, lowland tetraploid calls fare worse than both diploid and highland tetraploid calls, whereas diploid and highland tetraploid calls show different patterns of propagation in a few localities only.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 11–26.     

The influence of age and sex on the vocal repertoire of the Antillean manatee (Trichechus manatus manatus) and their responses to call playback

Limited information is available regarding the acoustic communication of Antillean manatees, however, studies have shown that other manatee taxa produce vocalizations as a method of individual recognition and communication. Here, the acoustic signals of 15 Antillean manatees in captivity were recorded, aiming to (1) describe their acoustic repertoire, (2) investigate the influence of sex and age on vocalization, and (3) examine manatee responses to call playback. Six acoustic signals ranging in mean fundamental frequencies from 0.64 kHz to 5.23 kHz were identified: squeaks and screeches were common to adult males, adult females, and juveniles; trills were common to adult males and females; whines were specific to males; creaks were specific to females; and rubbing was specific to juveniles. The structure of squeak vocalizations was significantly different between age and sex classes and screech structure was significantly different between age classes. Squeaks and screeches produced by juveniles had higher frequencies of maximum energy when compared to those produced by adult males and females. A significant increase in the vocalization rate following vocalization playbacks was found for all three age/sex groups. Our results introduce the potential of using acoustic signals in identifying and noninvasively monitoring manatees in the wild in Brazil.     

Habitat complexity and the structure of vocalizations: a test of the acoustic adaptation hypothesis in three rail species (Rallidae)

The acoustic adaptation hypothesis is based on the assumption that senders are directionally selected to maximize transmission and minimize degradation; however, the two aims are not necessarily convergent. In complex habitats, where more effects that might potentially cause attenuation and degradation co‐occur and longer transmission must incur a higher cost, signals should attenuate faster and have shorter transmission ranges. At the same time, such signals should be more resistant to degradation in order to preserve their communicatory function. Based on a sound transmission experiment, we tested the evidence for these predictions using territorial calls of three sympatric species of rails, inhabiting habitats with increasing complexity: Corncrake Crex crex, Spotted Crake Porzana porzana and Water Rail Rallus aquaticus. In the experiment, the calls were broadcasted with similar amplitudes through a heterogeneous habitat inhabited by all three species and rerecorded at different distances up to 320 m. Despite standardized amplitudes and habitats, calls of the species living in simpler habitats had longer transmission ranges but were more susceptible to degradation than calls of the species living in more complex habitats. Our results suggest that narrow frequency bandwidth is an adaptation of species inhabiting complex habitats that helps their calls to degrade less at the cost of stronger attenuation and shorter transmission range. By contrast, wide frequency bandwidth extends the range but increases degradation and thus it is used only by species inhabiting structurally simpler habitats. This study shows that, in more complex habitats, the clarity of the message is preserved at the cost of range.     

Motion perception and visual signal design in Anolis lizards

Anolis lizards communicate with displays consisting of motion of the head and body. Early portions of long-distance displays require movements that are effective at eliciting the attention of potential receivers. We studied signal-motion efficacy using a two-dimensional visual-motion detection (2DMD) model consisting of a grid of correlation-type elementary motion detectors. This 2DMD model has been shown to accurately predict Anolis lizard behavioural response. We tested different patterns of artificially generated motion and found that an abrupt 0.3° shift of position in less than 100 ms is optimal. We quantified motion in displays of 25 individuals from five species. Four species employ near-optimal movement patterns. We tested displays of these species using the 2DMD model on scenes with and without moderate wind. Display movements can easily be detected, even in the presence of windblown vegetation. The fifth species does not typically use the most effective display movements and display movements cannot be discerned by the 2DMD model in the presence of windblown vegetation. A number of Anolis species use abrupt up-and-down head movements approximately 10 mm in amplitude in displays, and these movements appear to be extremely effective for stimulating the receiver visual system.     

Call type signals caller goal: a new take on ultimate and proximate influences in vocal production

After 40 years of debate it remains unclear whether signallers produce vocalizations in order to provide receivers with information about call context or external stimuli. This has led some researchers to propose that call production is arousal‐ or affect‐based. Although arousal influences certain acoustic parameters within a call type, we argue that it cannot explain why individuals across vertebrates produce different call types. Given emerging evidence that calls are goal‐based, we argue that call type is a signal of a caller's goal to elicit a change in receiver behaviour. Using chimpanzees (Pan troglodytes) and vervet monkeys (Cercopithecus aethiops) as case studies, we demonstrate the two benefits of viewing call production as signalling both caller goal (which determines call type) and caller arousal (which affects within‐call‐type variation). Such a framework can explain first, why a single class of calls is apparently given in multiple contexts, and, second, why some species have larger call repertoires than others. Previous studies have noted links between sociality and repertoire size, but have not specified exactly why animals living in societies that are more complex might require a greater number of differentiated signals. The caller‐goal framework potentially clarifies how social complexity might favour call diversification. As social complexity increases, callers may need to elicit a larger number of distinct behaviours from a wider range of distinct audiences.     

Habitat Use by Waterbirds in Relation to Pond Size,Water Depth,and Isolation: Lessons from a Restoration in Southern Spain

Wetland restoration is increasingly important to reverse habitat degradation, recover ecosystem services, and maintain biodiversity. To aid project design, more information is required on the influence of wetland size, depth of water, and isolation on the waterbird communities that become established. During a restoration project in Doñana, one of the Europe's most important wetland complexes, an experimental network of 96 temporary ponds with standard shape but variable size, water depth, and isolation was created. We surveyed the waterbird community in spring from 2006 to 2008 and related species abundance and richness to abiotic pond characteristics. We also performed analyses pooling species by foraging guilds or body size. Waterbird abundance and species richness were highest in 2007, the wettest year when the ponds had longer hydroperiods. Larger ponds had consistently higher abundance and species richness for the entire community and for different guilds and body sizes. Moreover, the density of birds per hectare was higher in large ponds than in the smaller ones. Pond isolation and excavated depth did not affect overall abundance and richness, although opposing effects of depth were observed on some size classes, and ducks and large birds preferred isolated ponds. Some bird groups preferred ponds at a particular location. This is the first waterbird study to address the importance of pond size, depth, and isolation independently of confounding variables such as pond shape. It illustrates the varied responses from different bird groups and demonstrates the importance of varying depth, location, and isolation to enhance community abundance and diversity .     

Multimodal signals in male European treefrog (Hyla arborea) and the influence of population isolation on signal expression

In nocturnal treefrogs, mate choice implies the use of acoustic and visual signals. Multimodality is suspected to have evolved for either information redundancy or information complementariness. It is essential to explore multimodality in a natural context to understand the selection pressures operating on the signals. In the present study, we investigated calling and coloration in relation to male biometry and condition in four populations of European treefrog (Hyla arborea) varying in size and genetic isolation. We compared the signal intensity between core and satellite populations to estimate the impact of genetic diversity on male secondary sexual traits. The results obtained show important regional variations in both traits, likely as a result of local adaptations. Call and coloration are weakly correlated within an individual, implying that these traits likely convey different information about the signaller's identity or quality, thus supporting the hypothesis of complementariness of multiple messages. By contrast to the experimental evidence, we find that call and coloration are not related to male condition (as estimated by the residual of mass over size), suggesting that the condition‐dependence of these traits may be mediated by complex mechanisms not accurately reflected by the chosen estimator. Finally, male call and colour phenotypes present no robust pattern of variation with isolation status, probably because of variation in local selective pressures and in history of population dynamics. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 633–647.     

Physiological variation in metabolic phenotyping and functional genomic studies: use of orthogonal signal correction and PLS-DA

Metabolic phenotyping, or metabotyping, is increasingly being used as a probe in functional genomics studies. However, such profiling is subject to intrinsic physiological variation found in all animal populations. Using a nuclear magnetic resonance-based metabonomic approach, we show that diurnal variations in metabolism can obscure the interpretation of strain-related metabolic differences in two phenotypically normal mouse strains (C57BL10J and Alpk:ApfCD). To overcome this problem, diurnal-related metabolic variation was removed from these spectral data by application of orthogonal signal correction (OSC), a data filtering method. Interpretation of the removed orthogonal variation indicated that diurnal-related variation had been removed and that the AM samples contained higher levels of creatine, hippurate, trimethylamine, succinate, citrate and 2-oxo-glutarate and lower levels of taurine, trimethylamine-N-oxide, spermine and 3-hydroxy-iso-valerate relative to the PM samples. We propose OSC will have great potential removing confounding variation obscuring subtle changes in metabolism in functional genomic studies and will be of benefit to optimising interpretation of proteomic and genomic datasets.     

Genetic independence of female signal form and male receiver design in the almond moth, Cadra cautella

Efficient signalling requires coordination of signal form and receiver design. To maintain signal function, parallel changes in signaller and receiver traits are required. Genetic correlation and co-evolution among signal and response traits have been proposed to preserve signal function (i.e. coordination) during the evolution of mate recognition systems. Empirical studies have provided support for both mechanisms; however, there is debate regarding the interpretation of some of these studies. Tests for a genetic correlation typically hybridize divergent signalling systems and look at hybrid signal form and receiver design, or impose artificial selection on signal form and look for an indirect response to selection in receiver design. Some of the hybridization studies did not achieve reassortment of genes from the parental types, whereas some of the artificial selection studies incorporated random mating in their designs. As a result of these limitations, the hybridization studies cannot discriminate between genetic correlation and co-evolution with primarily additive genetic effects underlying signal and response traits. Similarly, the artificial selection experiments cannot discriminate between genetic correlation because of linkage disequilibrium and co-evolution. This study examined the mating preferences of male almond moths, Cadra cautella, before and after female moths were artificially selected (using a design incorporating assortative mating) for novel pheromone blend ratios. Our results demonstrate the absence of a genetic correlation between signal and response traits in the almond moth.     

Electrical signals and their physiological significance in plants

Electrical excitability and signalling, frequently associated with rapid responses to environmental stimuli, are well known in some algae and higher plants. The presence of electrical signals, such as action potentials (AP), in both animal and plant cells suggested that plant cells, too, make use of ion channels to transmit information over long distances. In the light of rapid progress in plant biology during the past decade, the assumption that electrical signals do not only trigger rapid leaf movements in 'sensitive' plants such as Mimosa pudica or Dionaea muscipula, but also physiological processes in ordinary plants proved to be correct. Summarizing recent progress in the field of electrical signalling in plants, the present review will focus on the generation and propagation of various electrical signals, their ways of transmission within the plant body and various physiological effects.     

人类血型性状综合遗传大实验的设计与教学实践

综合大实验能够训练学生灵活应用理论知识并掌握实验技能,成为当前实验课教学改革的重要方式。本文以人类的ABO血型性状为实验对象,设计了“人类ABO血型分子基因分型与群体遗传平衡分析”大实验。实验中提取同学唾液中黏膜细胞的DNA,经过PCR扩增目的片段、酶切及电泳分离一系列分子遗传技术分析,鉴定出每位同学的基因型;然后以全班同学为一个类似孟德尔群体调查ABO血型的各种基因型频数,用Popgene软件分析各种群体遗传参数。通过开放教学不仅让学生掌握了分子遗传实验技术和群体遗传分析技术及软件应用,还让学生自主设计方案优化分子技术环节,提高学生驾驭知识的能力。通过5年的教学探索与实践,建立了稳定的分子遗传实验体系,能够清楚地检测出ABO血型的6种基因型：I^AI^A、I^Ai、I^BI^B、I^Bi、I^AI^B、ii;综合了分子遗传与群体遗传的实验教学,统计全班同学6种基因型的频数,直接计算3个复等位基因的频率,进而应用软件分析群体遗传各种参数;实现了学生自主设计并完成实验的开放式实验教学;大实验教学获得了学生的好评,取得了很好的教学效果。该大实验可直接应用于生物类专业的遗传学实验教学,其中的教学理念和方法还可推广应用于其他生物学实验教学。     

Coexpression of the type I signal peptidase gene sipM increases recombinant protein production and export in Bacillus megaterium MS941

The removal of the signal peptide from a precursor protein is a crucial step of protein secretion. In order to improve Bacillus megaterium as protein production and secretion host, the influence of homologous type I signal peptidase SipM overproduction on recombinant Leuconostoc mesenteroides dextransucrase DsrS synthesis and export was investigated. The dsrS gene was integrated as a single copy into the chromosomal bgaM locus encoding beta-galactosidase. Desired clones were identified by blue-white selection. In this strain, the expression of sipM from a multicopy plasmid using its own promoter increased the amount of secreted DsrS 3.7-fold. This increase in protein secretion by SipM overproduction was next transferred to a high level DsrS production strain using a multicopy plasmid encoding sipM with its natural promoter and dsrS under control of a strong xylose-inducible promoter. No further increase in DsrS export were observed when this vector was carrying two sipM copies. Similarly, bicistronic sipM and dsrS high level expression did not enhance DsrS secretion, indicating the natural limitation of the approach. Interestingly, SipM-enhanced DsrS secretion also resulted in an overall increase of DsrS production.