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Interactions between species can affect the evolution of their sexual signals, receiver selectivity, or both. One commonly expected outcome is reproductive character displacement, whereby adverse consequences of mismating select for greater differentiation of communication systems in areas of sympatry than in areas of allopatry. We found evidence of reproductive character displacement in the acoustic communication system of green tree frogs (Hyla cinerea). The strength of female preferences for the spectral properties of calls that distinguish conspecific calls from those of a closely related congener, H. gratiosa, was greater in areas of sympatry with H. gratiosa than in areas of allopatry. We also found subtle differences in advertisement calls and in the heights of male calling perches when we restricted our comparisons to localities in which H. gratiosa was also breeding (syntopy) with localities where this species was absent. Hyla cinerea and H. gratiosa show only weak genetic incompatibility, but the calls representative of interspecific hybrids were unattractive to females of both parental species. Hybrids might also be at an ecological disadvantage because of different habitat preferences of the two taxa. Thus, selection against production of less fit or less attractive hybrid or backcross offspring are probably the main causes responsible for the differences documented in this paper.

Mimicry is a widespread phenomenon whereby predatory or parasitic individuals can access unsuspecting prey or hosts for the former’s benefit. For example, brood parasitic common cuckoos (Cuculus canorus) evolved several adaptations to trick hosts, including host-mimetic eggs, a barred chest plumage resembling the predatory Eurasian sparrowhawk (Accipiter nisus), and the female cuckoos’ bubbling calls considered as highly similar to this raptor’s calls. The sparrowhawk-like call mimicry is thought to threaten hosts while female cuckoos lay their eggs, although the similarity is restricted to the call’s fundamental frequency and not to its harmonics. However, these calls are also used in conspecific contexts, for example for mate attraction. If vocal mimicry is highly adapted toward the heterospecific function, it might cause reduced effectiveness in conspecific communication. We played cuckoo bubbling and sparrowhawk calls to territorial male cuckoos to test whether conspecific receivers process the mimetic calls accurately. All male cuckoos approached the speaker when female cuckoo calls were played, but rarely (7%) approached it when sparrowhawk or green woodpecker (Picus viridis; control) calls were played. When we excised the harmonic overtones from the sparrowhawk stimulus files, making these calls structurally more similar to the pure-tone female cuckoo calls, nearly half (43%) of the cuckoo males approached the speaker. Consequently, the difference in calls’ harmonic structure may explain one component of the inaccurate state of this acoustic mimicry. This imperfect mimicry by female cuckoos’ bubbling call to sparrowhawk call may ensure the multipurpose functions of this vocalization, including both intra- and interspecific contexts.Significance statementCommon cuckoos are obligate brood parasites, laying their eggs into other species’ nests. During laying, female cuckoos utter sparrowhawk-like vocalizations (bubbling calls), to threaten hosts and to evade their defenses. However, they also use this same call to communicate with other female and male cuckoos. If the bubbling call mimics closely sparrowhawks’ calls, cuckoos may also recognize and respond to the sparrowhawk call, the call of a predator, as a cuckoo call. We used playback experiments to show that cuckoos distinguished between bubbling and sparrowhawk calls in nearly all cases. When we manipulated sparrowhawk calls to be more similar acoustically to bubbling calls by deleting overtones, recognition errors increased from 7 to 43%. We conclude that mimicry of sparrowhawk calls by female cuckoo calls is imperfect, which allows it to function in cuckoo-cuckoo communication effectively.

Acoustic communication in obligate brood parasitic common cuckoos ( Cuculus canorus ) plays an important role both in social contacts within its own and with other species (including its many hosts). For example, the female cuckoo’s bubbling call putatively mimics the call of the Eurasian sparrowhawk ( Accipiter nisus ) to serve as defence from host songbirds mobbing the parasitic female. However, several other, both raptorial and harmless, sympatric bird species also have similar vocalizations to the bubbling call (including the Eurasian kestrel, Falco tinnunculus , and the Eurasian green woodpecker, Picus viridis ). Bubbling calls are also used by female cuckoos for conspecific communication with male conspecifics and so the discrimination of acoustically similar con- vs. heterospecific calls should be functionally relevant for cuckoos. We expanded upon a published playback study with all the above species’ calls presented to male cuckoos. The subjects approached the speaker in 100% when conspecific females’ bubbling calls were played back, but rarely (6–12%) did so when either acoustically similar natural calls of sympatric species were used. However, as structurally the bubbling call has no harmonic overtones, but the calls of the other species contain them, we also conducted playbacks with manipulated sound files where the harmonics were removed. Harmonic-free heterospecific calls attracted male cuckoos more often (40–50%) than natural heterospecific calls but still less so than the natural conspecific call. These results reveal the functional importance of the presence of harmonical overtones in heterospecific calls as they can serve to reduce perceptual auditory errors in male cuckoos.

Advertisement calls play a crucial role in anuran species recognition and mate selection, yet acoustic characteristics of remain undescribed. This study presents the first detailed acoustic analysis of advertisement calls in from Lishui, Zhejiang Province, China. Based on recordings from 13 males collected in the field during the breeding season, we documented a hierarchical call structure consisting of three note types (Initial Note, Middle Note, and Short Note) organized into two note groups (Note Group 1 (NG1) and Note Group 2). Four structural variants of NG1 were identified, revealing intra-individual acoustic diversity within the population. Compared to the closely related from the Dabie Mountains population, male produced calls with significantly longer temporal parameters but lower dominant frequency, despite overall structural similarity, indicating acoustic divergence between these taxa. Comparative analysis across eleven species revealed substantial variation in call durationand dominant frequency. These findings enrich the bioacoustic characterization of and establish a foundation for acoustic-based species identification, monitoring, and taxonomic studies in this genus.

Cloud computing is a well-known architecture that provides Computing and data Storage services remotely over Internet on a pay per usage model which results in better utilization of resources with reduced cost for individuals to access it. As Cloud Computing is a shared facility and is accessed remotely, it is vulnerable to various attacks including hosts and network based attacks that require immediate attention. This paper focuses on attacks that are due to malicious Syscall executions from subverted programs, Rootkits, Worms and Trojans on Hosts in a Cloud Computing environment. The paper critically describes and discusses the present techniques for malicious System Call detection and proposes a new Immediate Syscall signature structure based technique to determine malicious program executions in Cloud. The proposed technique is efficient in terms of complexity involved and resources utilized by it, so as to justify its feasible deployment is low cost and platform independent in Cloud environment. The proposed technique has also been validated on all available UNM (University of New Mexico) datasets and with a 98% accuracy in program wide detection for detecting intrusive processes. The functional prototype is deployed on a private Cloud environment using open nebula and virtual box for analysis and results.

Stabilizing selection is a fundamental concept in evolutionary biology. In the presence of a single intermediate optimum phenotype (fitness peak) on the fitness surface, stabilizing selection should cause the population to evolve toward such a peak. This prediction has seldom been tested, particularly for suites of correlated traits. The lack of tests for an evolutionary match between population means and adaptive peaks may be due, at least in part, to problems associated with empirically detecting multivariate stabilizing selection and with testing whether population means are at the peak of multivariate fitness surfaces. Here we show how canonical analysis of the fitness surface, combined with the estimation of confidence regions for stationary points on quadratic response surfaces, may be used to define multivariate stabilizing selection on a suite of traits and to establish whether natural populations reside on the multivariate peak. We manufactured artificial advertisement calls of the male cricket Teleogryllus commodus and played them back to females in laboratory phonotaxis trials to estimate the linear and nonlinear sexual selection that female phonotactic choice imposes on male call structure. Significant nonlinear selection on the major axes of the fitness surface was convex in nature and displayed an intermediate optimum, indicating multivariate stabilizing selection. The mean phenotypes of four independent samples of males, from the same population as the females used in phonotaxis trials, were within the 95% confidence region for the fitness peak. These experiments indicate that stabilizing sexual selection may play an important role in the evolution of male call properties in natural populations of T. commodus.

Bats rely heavily on echolocation for orientation and prey detection, hence acoustic signals that interfere with echo reception are problematic. When flying in the presence of other bats, some species adjust their echolocation to avoid frequency overlap with the calls of nearby conspecifics, known as a jamming avoidance response (JAR). One aspect of JAR that has not been thoroughly examined is how the spectral structure of the jamming signal impacts the jamming response. Our objective was to examine how the structural characteristics of an echolocation broadcast impact JAR in free-flying Brazilian free-tailed bats, Tadarida brasiliensis. We created 4 echolocation playbacks that differed only in call shape and frequency modulation. We examined the response of bats when flying in the presence of an unchanging broadcast (static stimulus) and when the playback signal was abruptly switched as the bat approached the speaker (dynamic stimulus). Results revealed that the bandwidth of the interfering signal impacted the strength of the observed JAR, while the presence and/or length of a terminal quasi-constant frequency section in the interfering signal did not. Our results agree with laboratory studies documenting JAR in the presence of white noise, as well as field studies demonstrating extensive variability in the echolocation calls of Brazilian free-tailed bats. We relate these results to previous findings on JAR, including a recent study documenting no JAR in a bat species and suggest further experiments to tease apart the physiological limitations of JAR. Overall, this study provides additional insight into the signal processing capabilities of bats and improves our understanding of how bats are able to orient using sound in a noisy world.

Auditory callback is the standard method for monitoring rails and other secretive marsh birds that live in concealing habitats. Due to recent population declines, monitoring the King Rail (Rallus elegans) has become a conservation priority. Analysis of field recordings (n = 542 calls or notes) and behavioral observations were combined to provide an account of the structure and function of the King Rail's vocal repertoire, which included 10 different vocalizations. King Rails produced an array of pulsed sounds by altering frequency, note length, pulse rate, and amplitude of each call. The most commonly heard call, the grunt (61 calls recorded; 37 individuals), had multiple functions including mate communication, duetting, and interaction with neighbors in a ‘roll call’ context. The kek (208 calls; 46 individuals) was the primary mate advertisement call. Most of King Rail's calls, including alarms (165 notes; 7 individuals), screeches (47 calls; 7 individuals), churrs (43 calls; 10 individuals), and the poorly documented boom (5 calls; 5 individuals), were used and sometimes combined in defense and distress situations. Although previously described as a signal of receptivity by females, the kek-burr may also be used in the context of defense. This synthesis is intended to assist researchers and managers in interpreting behavioral observations and improving effectiveness of audio lures for detecting or trapping King Rails.

BACKGROUND: To understand the evolution of acoustic communication in animals, it is important to distinguish between the structure and the usage of vocal signals, since both aspects are subject to different constraints. In terrestrial mammals, the structure of calls is largely innate, while individuals have a greater ability to actively initiate or withhold calls. In closely related taxa, one would therefore predict a higher flexibility in call usage compared to call structure. In the present study, we investigated the vocal repertoire of free living Guinea baboons (Papio papio) and examined the structure and usage of the animals’ vocal signals. Guinea baboons live in a complex multi-level social organization and exhibit a largely tolerant and affiliative social style, contrary to most other baboon taxa. To classify the vocal repertoire of male and female Guinea baboons, cluster analyses were used and focal observations were conducted to assess the usage of vocal signals in the particular contexts. RESULTS: In general, the vocal repertoire of Guinea baboons largely corresponded to the vocal repertoire other baboon taxa. The usage of calls, however, differed considerably from other baboon taxa and corresponded with the specific characteristics of the Guinea baboons’ social behaviour. While Guinea baboons showed a diminished usage of contest and display vocalizations (a common pattern observed in chacma baboons), they frequently used vocal signals during affiliative and greeting interactions. CONCLUSIONS: Our study shows that the call structure of primates is largely unaffected by the species’ social system (including grouping patterns and social interactions), while the usage of calls can be more flexibly adjusted, reflecting the quality of social interactions of the individuals. Our results support the view that the primary function of social signals is to regulate social interactions, and therefore the degree of competition and cooperation may be more important to explain variation in call usage than grouping patterns or group size.

Interactions between species can affect the evolution of their sexual signals, receiver selectivity, or both. One commonly expected outcome is reproductive character displacement, whereby adverse consequences of mismating select for greater differentiation of communication systems in areas of sympatry than in areas of allopatry. We found evidence of reproductive character displacement in the acoustic communication system of green tree frogs (Hyla cinerea). The strength of female preferences for the spectral properties of calls that distinguish conspecific calls from those of a closely related congener, H. gratiosa, was greater in areas of sympatry with H. gratiosa than in areas of allopatry. We also found subtle differences in advertisement calls and in the heights of male calling perches when we restricted our comparisons to localities in which H. gratiosa was also breeding (syntopy) with localities where this species was absent. Hyla cinerea and H. gratiosa show only weak genetic incompatibility, but the calls representative of interspecific hybrids were unattractive to females of both parental species. Hybrids might also be at an ecological disadvantage because of different habitat preferences of the two taxa. Thus, selection against production of less fit or less attractive hybrid or backcross offspring are probably the main causes responsible for the differences documented in this paper.