John Hunt of the University of New South Wales in Australia and his colleagues observed two groups of field crickets. One group ate a restrictive, low-protein diet whereas the other dined on protein-rich foods. The researchers monitored the creatures' size, mating behavior and how long they lived. For female crickets, those fed a robust diet lived longer than did their protein-starved counterparts. This pattern did not hold for the males, however. Instead, the well-fed males used their extra energy to woo female partners by calling more extensively during early adulthood and experienced shortened life spans as a result. "They literally knocked themselves out trying to impress female crickets," says study co-author Luc F. Bussiere, also at the University of New South Wales.
The findings demonstrate that the best reproductive strategy in the animal kingdom does not always coincide with living a long life. What is more, long-lived males are not necessarily those in the best condition, which indicates that longevity is not always a reliable measure of male quality. "One thing that consistently prolongs life span in a range of species is a restricted diet," remarks co-author Rob Brooks of the University of New South Wales. "Now we know a bit more about how this occurs in male crickets--by suppressing sexual advertisement."