Can’t Hear You …

Grasshoppers Change Courtship Tunes to Cope With Urban Noises

Grasshoppers in urban areas are changing the tune of their courtship songs so as to be heard over the sound of traffic.  […] A team of researchers from the University of Bielefeld in Germany observed the bow-winged grasshoppers in order to understand the effect of human-made noise like traffic on their communication.

“Bow-winged grasshoppers produce songs that include low and high frequency components. We found that grasshoppers from noisy habitats boost the volume of the lower-frequency part of their song, which makes sense since road noise can mask signals in this part of the frequency spectrum,” Lampe said in a statement.

Male grasshoppers have been able to adapt to the increasing noise by changing their tune. Lampe suggests that the change is a long-term effect and “not a spontaneous behavioral adaptation to noise,” a report in National Geographic said.

The findings of the study, “Staying tuned: grasshoppers from noisy roadside habitats produce courtship signals with elevated frequency components”, are published in the journal Functional Ecology.

It’s a simple example of natural selection in action.  Those grasshoppers that had a genetic predisposition to a louder low-frequency element to their mating call suddenly had an advantage to their higher-frequency counterparts.  Over the course of time, the mating calls of the entire population gradually shifted to favor the low end of the spectrum … selected by the noise that filtered out the part that the females couldn’t hear.

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