Do male poison frogs respond to modified calls of a Müllerian mimic?

It was a question asked by a group of scientists who were studying frogs in the Amazon (Peru). In that region there are two different species of frog that look similar. They are Ranitomeya imitator and Ranitomeya variabilis. This interesting question is based on the hypothesis that as they are similar so perhaps they could be confused with the call of the mimetic species.  

Ranitomeya imitator

Ranitomeya variabilis

Ranitomeya imitator is a small poison frog from Amazonian Peru. Males show strong territoriality and often fight with conspecific male intruders, especially when intruders are producing advertisement calls. This species is a Müllerian mimic with various species in the same genus. In the study the scientists used Ranitomeya variabilis to find the answer. Both types of frogs use vibrant colors to advice their predators that they are dangerous. 

R. imitator is more aggressive. Also, the males call to claim territories and to attract females while R. variabilis males call during courtship only. The calls of both frogs were recorded and played in four different frequencies, two were identical to the real frogs and two were with different temporal properties. The scientists used playbacks and they analysed reactions that the frogs could do. One expected reaction is the frog approach the sound when played.  

As expected the R. imitator frogs approached when was played their own song, even when the song was modified. However, the frogs do not demonstrate reaction when was played the song from R. variabilis frog even when was played the modified song from R. variabilis frog that was more similar with R. imitator call. 

The scientists concluded that R. imitator differentiate calls from R. variabilis through more complex factors because they could realise the difference even when was changed the frequencies. The researchers believe that the frogs have this precise perception because they have big energetic cost to make the call. So, they cannot waste this precious energy in the competitive wildlife.

Although mimicry is a great evolutionary characteristic, there is some aspects where this process cannot be seen. We can conclude that even animals are very similar, they have some aspect that will make they unique.

You can find more details: 

Text Reference

Mayer, M. et al (2013) Do male poison frogs respond to modified calls of a Müllerian mimic? Animal Behaviour, vol.89,pp.45-51.

Retrieved from: Animal Behaviour  

Pictures References

Click here: Ranitomeya variabilis

                    Ranitomeya imitator