@article {58461, title = {Acoustic radiation patterns of mating calls of the t{\'u}ngara frog (Physalaemus pustuosus): Implications for multiple receivers}, volume = {126}, year = {2009}, month = {Nov-01-2009}, pages = {2757-2767}, abstract = {

In order for a signal to be transmitted from a sender to a receiver, the receiver must be within theactive space of the signal. If patterns of sound radiation are not omnidirectional, the position as wellas the distance of the receiver relative to the sender is critical. In previous measurements of thehorizontal directivity of mating calls of frogs, the signals were analyzed using peak orroot-mean-square analysis and resulted in broadband directivities that ranged from negligible to amaximum of approximately 5 dB. Idealized laboratory measurements of the patterns of acousticradiation of the mating calls of male t\úngara frogs\ Physalaemus pustulosus, along axes relevant tothree receivers in this communication network, female frogs in the horizontal plane, and frog-eatingbats and blood-sucking flies above the ground, are reported. The highest sound pressure level wasradiated directly above the frog, with a 6 dB reduction radiated along the horizontal direction.Band-limited directivities were significantly greater than broadband directivities, with a maximumdirectivity of 20 dB in the vertical plane for harmonics near 6 kHz. The implications with regard tomating and predator-prey interactions are discussed.

}, issn = {0001-4966}, doi = {10.1121/1.3212929}, url = {http://dx.doi.org/10.1121/1.3212929}, author = {Bernal, Ximena E. and Page, Rachel A. and Ryan, Michael J. and Argo, Theodore F. and Wilson, Preston S.} } @inbook {57555, title = {Be loved, be prey, be eaten}, year = {2014}, abstract = {

Animal communication is one of the most fundamental of all social behaviors. It modulates interactions among neighbors and strangers, siblings and parents, and individuals and their prospective mates. One of the most fundamental functions of communication is to enhance the sender\’s conspicuousness, to cause the sender to stand out against the background so it can be detected by the receiver. This is a challenge for signals that function over long distances, such as those that function in territorial advertisement and mate attraction, because signal intensity and fidelity decrease with distance from the sender. At longer distances a signal is less likely to be above the receiver\’s threshold for detection and recognition, and it is also more likely to be masked by noise as the intensity of noise at the receiver is independent of its distance from the sender.

Another type of noise is generated by conspecifics signaling in the same channel. We may perceive a chorus of frogs or insects as a melodious, even co- operative unit. But to members of the chorus the calls of their neighbors are every bit as deleterious to their own call\’s ability to be detected as is environ- mental noise. There is also \“noise\” within the perceptual systems of the receiver that ameliorates signal detection. One example is habituation. Upon continual exposure to a signal, an animal will tend to ignore it, and some of the animal\’s neurons will cease to fire. Another type of perceptual noise is incremental forgetting of a signal once it is perceived. Some signals are more\ memorable than others, surviving longer in the receiver\’s memory. The importance of conspecific noise and perceptual noise is usually less appreciated in animal communication studies than is environmental noise.

Selection often will favor senders to produce communication signals that stand out against these three types of background noise. Conspicuousness is accomplished in a variety of ways. In the acoustic domain animals can use fre- quency bands that contain less noise; they can call longer, at a faster rate, or at a higher amplitude; they can call during periods when others are silent; and they can produce calls that are more complex. Visual signals can stand out more against background when their spectral properties and spatial patterns differ from those in the background, when colors are brighter and patterns are more complex, and when motion patterns associated with the signal, such as push-up displays in lizards, are different than the pattern of background movement, such as vegetation being blow in the wind (e.g., Fleishman, 1992). Increasing signal complexity in both the acoustic and visual domains can to some extent remedy the receiver habituating to and forgetting a signal. There is less known about how chemical, tactile, and electrical signals can enhance contrast with the background.

In a survey of preferences for sexual signals, Michael Ryan and Anne Keddy-Hector (1992) showed that across modalities prospective mates tended to prefer sexual signals that were greater in magnitude: longer and louder, faster and brighter, more complex and with more background contrast. Although there were numerous cases in which prospective mates preferred signals that were near the population mean, there were few cases in which there was a preference for signals of lesser magnitude. A simple rule of thumb for sexual signals is that more is better. Selection for signal efficacy, however, creates a dilemma for the sender: the curse of unintended receivers. In general, each signal has evolved under selection to communi- cate with a specific intended receiver. In the case of sexual advertisement sig- nals, the intended receivers are prospective mates, usually female conspecifics. Other receivers can also detect and respond to signals even if there was no selection on the sender to communicate with them. We refer to these receivers as eavesdroppers or unintended receivers. It is important to note that the terms intended and unintended should not imply intention- ality but instead refer to hypotheses about the selection forces that favored the evolution of these signals. With few exceptions, senders and receivers do not communicate in a private channel. The world is populated by unin- tended receivers, eavesdroppers who are attendant to the signals of senders, often to the demise of senders. In this chapter we explore the tension that exists in sexual communication systems between being conspicuous to\ potential mates and attracting eavesdroppers, between being loved, being prey, and being eaten.

}, author = {Rachel A. Page and Michael J. Ryan and Ximena E. Bernal} } @article {53584, title = {Environmental constraints on size-dependent signaling affects mating and rival interactions}, journal = {Behavioral Ecology}, year = {2019}, month = {Mar-02-2020}, abstract = {

Advertisement signals can convey information about a sender\’s characteristics, such as body size. The reliability of signals, however, can be reduced when signal production is partially dependent on the environment. Here, we assess the effect of display-site properties on the production, attractiveness and honesty of sexual signals. We recorded male t\úngara frogs (Physalaemus pustulosus) while manipulating water levels in order to constrain calling. We found that water level affected male call properties in a size-dependent manner, with call amplitude being less affected in smaller males when forced to call in shallow water. Next, we tested how size-dependent and display-site-dependent signaling affected female choice and rival competition. Both males and females showed the strongest response to the call of a large male when he was calling at the deepest water levels. However, females showed no preference for large over small males when both were recorded in shallow water levels, or, depending on the call rate and timing of calls, even preferred small males. Likewise, males responded equally to large and small rivals recorded calling during shallow water level trials. Our experiments show that display-site properties can influence signal production and attractiveness in a size-dependent manner. These results can have important consequences for the evolution of signaling, as small males may be able to use their size to their advantage when selecting appropriate display sites and thereby outcompete large males.

}, keywords = {display site, honest signaling, Physalaemus pustulosus, production constraints, sexual selection}, issn = {1045-2249}, doi = {10.1093/beheco/arz009}, url = {https://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arz009/5320523}, author = {Smit, Judith A H and Loning, Hugo and Halfwerk, Wouter} } @article {53414, title = {Behavioral and neural auditory thresholds in a frog}, journal = {Current Zoology}, year = {2018}, abstract = {

Vocalizations play a critical role in mate recognition and mate choice in a number of taxa, especially, but not limited to, orthopterans, frogs, and birds. But receivers can only recognize and prefer sounds that they can hear. Thus a fundamental question linking neurobiology and sexual selection asks\— what is the threshold for detecting acoustic sexual displays? In this study we use three methods to assess such thresholds in t\úngara frogs: behavioral responses, auditory brainstem responses, and multi-unit electrophysiological recordings from the midbrain. We show that thresholds are lowest for multi-unit recordings (ca. 45 dB SPL), and then for behavioral responses (ca. 61 dB SPL), with auditory brainstem responses exhibiting the highest thresholds (ca. 71 dB SPL). We discuss why these estimates differ and why, as with other studies, it is unlikely that they should be the same. Although all of these studies estimate thresholds they are not measuring the same thresholds; behavioral thresholds are based on signal salience while the two neural assays estimate physiological thresholds. All three estimates, however, make it clear that to have an appreciation for detection and salience of acoustic signals we must listen to those signals through the ears of the receivers.

}, keywords = {anurans, auditory brainstem responses, auditory thresholds, mate choice, Physalaemus pustulosus, sexual selection, signal recognition thresholds, t{\'u}ngara frogs, vocalizations}, author = {Ryan, C and Akre, Karin and Wilczynski, Walter and others} } @article {52575, title = {Interactions between complex multisensory signal components result in unexpected mate choice responses}, journal = {Animal Behaviour}, volume = {134}, year = {2017}, month = {Jan-12-2017}, pages = {239 - 247}, abstract = {

Multimodal (multisensory) signalling is common in many species and often facilitates communication. How receivers integrate individual signal components of multisensory displays, especially with regard to variance in signal complexity, has received relatively little attention. In nature, male t\úngara frogs, Physalaemus pustulosus, produce multisensory courtship signals by vocalizing and presenting their inflating and deflating vocal sac as a visual cue. Males can produce a simple call (whine only) or a complex call (whine \þ one or more chucks). In a series of two-choice experiments, we tested female preferences for variation in acoustic call complexity and amplitude (unimodal signals). We then tested preferences for the same calls when a dynamic robotic frog was added to one call, generating a multi- modal stimulus. Females preferred a complex call to a simple call; when both calls contained at least one chuck, additional numbers of chucks did not further increase attractiveness. When calls contained zero or one chuck, the visual stimulus of the robofrog increased call attractiveness. When calls contained multiple chucks, however, the visual component failed to enhance call attractiveness. Females also preferred higher amplitude calls and the addition of the visual component to a lower amplitude call did not alter this preference. At relatively small amplitude differences, however, the visual signal increased overall discrimination between the calls. These results indicate that the visual signal component does not provide simple enhancement of call attractiveness. Instead, females integrate multisensory components in a nonlinear fashion. The resulting perception and behavioural response to complex signals probably evolved in response to animals that communicate in noisy environments.

}, keywords = {anurans, mate choice, multimodal signalling, nonlinear interactions, sexual selection, signal weighting, t{\'u}ngara frog, vocal sac}, issn = {00033472}, doi = {10.1016/j.anbehav.2016.07.005}, url = {http://linkinghub.elsevier.com/retrieve/pii/S000334721630121X}, author = {Stange, Nicole and Rachel A. Page and Michael J. Ryan and Taylor, Ryan C.} }