Mute crickets evolve at the same time but not in the same place...

When male crickets rub their wings together to chirp and attract females, parasitic flies can pinpoint their location. A pregnant parasitic fly will spray baby maggots onto the crickets back, which burrow in, feed and emerge a week later.

fly spraying baby maggots onto cricket

Crickets on the Hawaiian Island of Kauai have evolved an inability to sing. This adaptation prevents the cricket from being pinpointed and eaten by maggots.

What is astonishing about this case of Natural Selection is that it occurred in just the blink of an eye in evolutionary time. In just 20 generations a mutation that left males unable to sing spread to over 90% of the population of Kauai. This shows the awesome power of selective pressures.

Equally interesting is the fact that two years after these mute crickets where discovered in Kauai, crickets on another Hawaiian island, Oahu, were discovered to also be silent. It seems amazing that a trait can evolve twice almost at the same time among two completely different populations, separated by over 100 km of sea. the traits are known to have evolved independently because the mutant silent wings on each island have different shapes.

mutant wings which produce no noise when rubbed together

This is known as 'convergent evolution', when the same feature evolves separately in two distinct populations. It is impressive to think that silent crickets could evolve just once, but for the mutations to have resulted in the evolution of mute crickets twice is a truly amazing coincidence.