Most amphibians have mating displays that are usually structured (i.e., a specific sequence of components in the signal) and partners can decode such sequences of signal components, which are genetically determined (i.e., they are not learned). For instance, such body movements might be a rather chaotic visual display in a vocalizing male that is trying to "scare away" the parasitic flies. However, it is not clear how much of this antiparasitic (swatting) behavior has become a component of the mating display. These alleged visual cues capture the attention of females and effectively enhance the sensory components of this mating display. This study provides an intriguing hypothesis - namely, that mating displays might become more attractive if males are engaged in antiparasitic movements. Interestingly, such body movements, including foot-flagging and leg-stretching, if combined with mating calls, seem to make males more attractive to females. Then, the authors showed evidence that, when males call, these animals tend to attract more midge parasites and such interaction increased the frequency of limb movements as males try to swat away these midges. For this purpose, the researchers filmed frogs in the field and classified their limb displays. The authors hypothesize that limb movement has been adopted as part of a multimodal mating display where limb movements and vocalizations further entice female preference. By studying such displays, the authors show that body movements in males might increase female preference for them in addition of the acoustic signal. Such interaction seems to incite the males to move their limbs as if they are trying to swat away the parasites. The authors show that the acoustic signals might also attract unintended parasites in this case, midges (small flies) that locate vocalizing males and try to get a blood-meal. Males of this species are active during day and night and their displays include acoustic and visual cues that attract females.
Predators evolution torrent torrent#
In the present study, the authors focused on the evolution of mating signals in torrent frogs (Amolops torrentis) from noisy mountain streams of the Hainan Island (China). In anurans (frogs and toads), the dominant mating signals are acoustic, but visual cues can be combined in the courtship display if the signalers are active during the day and combine those with their vocalizations. However, most signalers avoid being detected by predators in their habitat, thus there is generally a conflict between signal detectability by partners and predation avoidance by signalers. Such complex signals might allow receivers to better decode information about the signaler (e.g., genetic quality, health, resources). Depending on the context, some signals might include more than one information channel and become multimodal (e.g., visual + acoustic). Natural selection (and sexual selection) usually can shape how exclusive such signals become for their intended receivers. Such signals transfer information about the signaler to an intended receiver that decodes such cues. Organisms communicate using different sets of signals, ranging from visual, acoustic, chemical, to tactile cues. Our results thus help to understand the relationship between ecological and sexual selection pressure operating on signalers and how in turn this may influence multimodal signal evolution. Females may play an important role in incorporating these multiple components because they prefer signals which combine multiple programs. Our data suggest that midge-induced movements may be incorporated into a sexual display, targeting both hearing and vision in the intended receiver.
Through mate choice tests we show that some of these midge-evoked movements influence female preference for acoustic signals. Calling males of this species often display limb movements in order to defend against blood-sucking parasites such as frog-biting midges that eavesdrop on their acoustic signal.
Here we assess whether the physical movements of parasite defense behavior increase the complexity and attractiveness of an acoustic sexual signal in the little torrent frog (
Despite being taxonomically widespread, we often lack insight into how multimodal signals evolve from unimodal signals and in particular what roles unintended eavesdroppers play.
Predators evolution torrent driver#
These multimodal mating displays can however also attract unintended receivers, which can be an important driver of signal complexity. Many animals rely on complex sexual signals that target multiple senses to attract mates and repel rivals.
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