To understand just how serious the cheating was, muscle physiologist Rob James from Coventry University, UK, measured how much force crayfish muscles produce. He found that the muscles of female crayfish are actually more powerful than those of males. 'So males are not only cheating by creating large chelae with little muscle inside, but the muscle they do put in there is actually weaker,' Wilson concludes.
But these findings still didn't explain how males get away with cheating. Wilson wondered if there might be a disadvantage to growing large claws if growing intimidating weapons is costly, this would ensure that males' unwieldy claws are actually a reliable signal of their prowess. To test whether large claws might be a handicap when it comes to escaping danger, Wilson and Bywater measured how quickly crayfish sped off when startled. Sure enough, while females' swimming performance was unaffected, 'the large claws of the cheating males reduced their swimming speed,' Wilson says. This suggests a potentially serious fitness cost to growing large claws; males encumbered by big claws may end up as a predator's lunch.
According to Wilson, the importance of dishonesty in weapon signalling is underappreciated, and may play a larger role than previously suspected. The next step, he says, is to 'find out how frequently cheating occurs in nature.'
|Contact: Kathryn Knight|
The Company of Biologists