Multimodal stimuli regulate reproductive behavior and physiology in male túngara frogs

• Published in: Hormones and behavior 2019-09, Vol.115, p.104546-104546, Article 104546
• Main Authors: Still, Meghan B., Lea, Amanda M., Hofmann, Hans A., Ryan, Michael J.
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; Amphibian; Androgen; Animals; Anura - metabolism; Anura - physiology; Behavior, Animal - physiology; Chemical cue; Complex signal; Corticosterone - metabolism; Courtship; Glucocorticoid; Male; Multimodal communication; Multisensory stimulus; Non-invasive endocrinology; Sexual Behavior, Animal - physiology; Social Behavior; Testosterone - metabolism
• ISSN: 0018-506X; 1095-6867
• DOI: 10.1016/j.yhbeh.2019.06.010

Unlike in terrestrial animals, the boundary between internal (e.g., hormones) and external (e.g., social) stimulation can be blurred for aquatic and amphibious species. When chemicals such as hormones and glandular secretions leach into the water, they can further interact with other signaling systems, creating multimodal stimuli. It is unclear, however, whether water-borne chemical secretions from courting male frogs affect the physiology and behavior of their rivals. In order to address this question we first established non-invasive, continuous sampling methods for simultaneously measuring both hormones and behavior in amphibious species. Then, we examined whether interactions between water-borne chemical secretions and conspecific calls affect reproductive behavior and physiology (testosterone and corticosterone) of courting male túngara frogs. Our results demonstrate that conspecific acoustic stimulation alone increases locomotor activity, decreases latency to call, and increases calling behavior but does not alter the amount of hormones excreted. In response to water containing chemical secretions from rivals, but in the absence of calls from other males, males excrete more testosterone. Interestingly, the combined acoustic and chemical stimulus causes a multiplicative increase in both calling behavior and hormonal excretion. Taken together, our results suggest that a multimodal chemical-acoustic stimulus physiologically primes males for aggressive behavior. •Male frogs perceive and respond to water-borne chemical secretions from rivals.•Acoustic stimulation enhances locomotor activity, motivation to call, and calling.•Chemical stimulation enhances androgen excretion.•Multimodal stimulation multiplicatively increases behavioral and hormonal responses.