City frogs are sexier: evolutionary or courtship?

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 City frogs are sexier: evolutionary or courtship?

Output | Five Wangs in Netease Scientists Section

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Photo Source: SMITHSONIAN Tropical Research Institute and WOUTERHALFWERK

Tungara frogs live on the edge of tropical forests from Mexico to northern South America. With the development of cities, they eventually enter urban areas. A report in Nature Ecology and Evolution shows that when they live in urban environments, their mating habits change.

According to United Nations statistics, by 2050, nearly 70% of the worlds population will live in urban environments. But with the spread of cities, wildlife has to adapt. A report by the Smithsonian Tropical Research Institute (STRI) shows that male Tungara frogs in Panama City exhibit sexier mating behavior than frogs living in nearby tropical forests.

Tungara frog sounds like a pinball machine, said Wouter Halfwerk, an assistant professor at Free University in Amsterdam and a visiting scientist with STRI. In addition to simpletunsounds, they can add additional elements, such asgara sounds, to carry out complex calls: Tun Gara Gara - which is why they are named.

Some people call the tiny Tungara frog an acoustic equivalent of a peacock. They have nothing else to pay attention to, but just as male peacocks attract females with their fancy tails, Tungara frogs add extra sounds to their calls to attract females.

But female frogs arent the only creatures that pay attention to male Tungara frogslove songs. Predatory bats and parasitic flies use the same sound to locate their food. So when frogs know that predators exist, they dont add extra gara sounds.

In Panama City, Tungara frogs live in a variety of urban environments: from ditches and puddles near tropical forests to drains between skyscrapers in the city centre. When City frogs call to attract females, how do they compare with forest frogs?

In their first experiment, Halfwerks team played voice recordings of male Tungara frogs in 22 urban and forest locations, and used remote infrared cameras to record the number of approaching female frogs, predators and parasites.

In cities, fewer females respond to calls than males do. Maybe there are only a few females in cities to choose from, or males need to work harder to attract femalesattention. In addition, the recording of the calls did not attract any bats, but only a few flies. This suggests that predators pose less threat to frogs in cities.

To confirm that male frogs in cities adjusted their calls, researchers recorded the calls of up to 100 male frogs at the same location and found that male frogs in cities emitted higher frequencies, more complex and more obvious calls than frogs in forests.

Finally, they began to wonder how long it would take frogs to adjust their calls. When they took frogs from the forest to the city and from the city to the forest, they found that the urban male frog in the forest immediately became a simple, consistent cry with the forest frog. Male forest frogs entering the city do not immediately make complex calls. Therefore, the drivers of male vocal changes seem to be more intense competition for females and fewer predators and parasites in cities.

Humans have caused tremendous changes in biological communities worldwide, and just as we have changed social relationships in cities, animals are also changing relationships and behaviors in biological communities, said Rachel Page, a scientist and co-author of STRI.

Source: Liable Editor of Netease Scientist: Qiao Junyi_NBJ11279