Cosmopolitan Croakers: Túngara Frogs

Photo by Brian Gratwicke via wikimedia commons

Something about the city gives a guy a certain something that a female frog just can’t resist.

Researchers have discovered that male túngara frogs living in the city have more complex mating calls than their country cousins. Three out of four females prefer the city call. But if the city slicker moves to the country, his sophisticated ways may get him into trouble. Bubba Frog knows that out in the forest his fancy song attracts more than the ladies. It’s the same as yelling, “Here’s a tasty frog! Come and eat me!” to every hungry bat and snake within earshot.

So why does living in the city make a difference? Potential mates aren’t as numerous in the city, creating pressure for the frogs to sing a more attractive song. At the same time, predators in the city are fewer too, so there’s less pressure for a frog to avoid advertising his presence. The researchers sum it up this way: “As animals move into urban environments, they face different pressures from natural selection, resulting in rapid evolution of different behaviors.”

A better explanation is that God gave frogs—as well as other animals—the tools to “fill” the varied niches on earth as he commanded. The earth has not always been covered with cities, so animals’ abilities to display specialized behaviors in the city reflect flexibility designed into the system. Even the researchers admitted the frog population already had some variation from the start. When the frogs found themselves in the city, they didn’t evolve into something else. Frogs remain frogs, even when they put on airs and get all citified.

This article was taken from Answers magazine, May–June, 2019, 20.