Behavioral Ecology Blog

I’m quite sure many of my readers are familiar with Mike Ryan’s work on the Tungara frogs and their communication. Whines, chucks, and all that cool stuff. Yes? Amongst other things, he (and his collaborators) have shown that females prefer complex mating calls. If you are a male Tungara frog, you better have a nice call, lest you get few matings. If you have not read this series of papers, I highly suggest them.

Anyway, according to their most recent paper, published in American Naturalist, female tungara frogs are not the only ones listening. In a nutshell, in addition to complex calls attracting mates, it also attracts ectoparasites…

ABSTRACT

Predators and parasites that eavesdrop on the mating signals of their prey often preferentially select individuals within a prey/host species that produce specific cues. Mechanisms driving such signal preferences are poorly understood. In the túngara frog Physalaemus pustulosus, conspecific females, frog-eating bats, and blood-sucking flies all prefer complex to simple mating calls. In this study we assess the natural signal variation in choruses in the wild and test two hypotheses for why eavesdroppers prefer complex calls: (1) prey quality: complex calls indicate better quality of prey/host, and (2) prey density: complex calls indicate higher prey/host density. Call complexity is not correlated with frog length, mass, or body condition, but it does signal higher abundance of prey/host. Thus, increased effectiveness of attack may have played a role favoring the preference for complex calls in eavesdropping heterospecifics.

Guys, this is really cool! Potential mates have a good reason to listen, as males that sing better make better babies, but the idea that parasites differentially affect individuals within a given population based on something abstract like song complexity is really novel. Their data are pretty convincing, and it does not seem to be based being more conspicuous. They suggest that aside from being better mates, males with complex calls make better hosts.. Cool.. You traditionally think of male advertisement in the context of an honest signal of quality- but here, that just isn’t the case..

There are a couple of cool videos (here and here), showing the parasitism in action. I can’t seem to embed them… The files are .avi, and relatively large…

I wonder if this is a patterns that could be observed commonly? If their idea that better mates make better hosts, I wouldn‘t be so surprised…