Tue Feb 13, 7:08 PM ET
Scientists at the Universities of Exeter and Glasgow have found that female green swordtail fish mature more rapidly if they spot a male with a big tail.
Likewise young males retard their sexual development for several months if they spot a better-endowed male, waiting for there to be less competition in the mating game.
"This is the first evidence that a species adjusts its rate of sexual maturation in response to visual clues," Craig Walling of Exeter University's school of biosciences said.
"While our study focused on green swordtail fish, it seems unlikely that this attribute is limited to this one species," he added.
Green swordtail fish, a native of North and Central America, are named after the striking growth of the male's tail-fin which makes them look bigger and therefore more attractive to females which do not develop the sword-shaped tail fin.
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