How the world's fastest muscle created four unique bird species

Date:  October 30, 2018

Source:  Wake Forest University

When the male bearded manakin snaps its wings at lightning speed, it's more than part of an elaborate, acrobatic mating ritual. The tiny muscle doing the heavy lifting is also the reason this exotic bird has evolved into four distinct species, according to new research published in the journal eLIFE by Wake Forest University biologist Matthew Fuxjager.

Fuxjager's previous research showed that the tiny bearded manakin, which measures a little more than four inches long and weighs about half an ounce, has one of the fastest limb muscles of any vertebrate. During an elaborate courtship dance, it uses this muscle -- the scapulohumeralis caudalis -- to make a unique "roll-snap" movement at speeds so fast it's undetectable to the human eye. The roll-snap creates a mechanical popping sound when the wings connect above the back, all to catch the female's attention.

"The ability of this muscle to develop different speeds has shaped the way these manakins have evolved -- allowed for one species to become two, and two to become four," said Matthew Fuxjager, one of the world's few experts on manakin physiology. "This is some of the first work that shows how this happens."

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