Alteration of the temporal association between courtship audio and visual components affects female sexual response

Some multimodal signals-that is,occurring in more than one sensory modality-appear to carry additional information which is not present when component signals are presented separately.To understand the function of male ring dove’s(Streptopelia risoria)multimodal courtship,we used audiovisual playback of male displays to investigate female response to stimuli differing in their audiovisual timing.From natural courtship recordings,we created a shifted stimulus where audio was shifted relative to video by afixed value and a jittered stimulus,where each call was moved randomly along the visual channel.We presented 3 groups of females with the same stimulus type,that is,control,shifted,and jittered,for 7 days.We recorded their behavior and assessed pre-and post-test blood estradiol concentration.We found that playback exposure increased estradiol levels,confirming that this technique can be efficiently used to study doves’sexual communication.Additionally,chasing behavior(indicating sexual stimulation)increased over experimental days only in the control condition,suggesting a role of multimodal timing on female response.This stresses the importance of signal configuration in multimodal communication,as additional information is likely to be contained in the temporal association between modalities.

Acoustic and visual adaptations to predation risk: a predator affects communication in vocal female fish

Predation is an important ecological constraint that influences communication in animals.Fish respond to predators by adjusting their visual signaling behavior,but the responses in calling behavior in the presence of a visually detected predator are largely unknown.We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator.To test this we investigated dyadic contests in female croaking gouramis(Trichopsis vittata,Osphronemidae)in the presence and absence of a predator(Astronotus ocella-tus,Cichlidae)in an adjoining tank.Agonistic behavior in T.vittata consists of lateral(visual)displays,antiparallel circling,and production of croaking sounds and may escalate to frontal displays.We analyzed the number and duration of lateral display bouts,the number,duration,sound pressure level,and dominant frequency of croaking sounds as well as contest outcomes.The number and duration of lateral displays decreased significantly in predator when compared with nopredator trials.Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics.In the presence of a predator,dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays.The gouramis showed approaching behavior toward the predator between lateral displays.This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish.Sound properties,in contrast,did not change.Decreased signaling and the lack of escalating contests reduce the fish's conspicuousness and thus predation threat.

Telomere shortening is associated with corticosterone stress response in adult barn swallows

When vertebrates face stressful events,the hypothalamic–pituitary–adrenal(HPA)axis is activated,generating a rapid increase in circulating glucocorticoid(GC)stress hormones followed by a return to baseline levels.However,repeated activation of HPA axis may lead to increase in oxidative stress.One target of oxidative stress is telomeres,nucleoprotein complexes at the end of chromosomes that shorten at each cell division.The susceptibility of telomeres to oxidizing molecules has led to the hypothesis that increased GC levels boost telomere shortening,but studies on this link are scanty.We studied if,in barn swallows Hirundo rustica,changes in adult erythrocyte telomere length between 2 consecutive breeding seasons are related to corticosterone(CORT)(the main avian GC)stress response induced by a standard capture-restraint protocol.Within-individual telomere length did not significantly change between consecutive breeding seasons.Second-year individuals showed the highest increase in circulating CORT concentrations following restraint.Moreover,we found a decline in female stress response along the breeding season.In addition,telomere shortening covaried with the stress response:a delayed activation of the negative feedback loop terminating the stress response was associated with greater telomere attrition.Hence,among-individual variation in stress response may affect telomere dynamics.