Costs of mating with males possessing long tails in the female guppy

Abstract

Males of the guppy Poecilia reticulata have longer tails (caudal fins) than females, and the tail lengths of males show a high individual variation. Female guppies in a population exhibit mate preference on the basis of the total length of the males, and not their tail lengths. Therefore, the occurrence of long tails in male guppies has been suggested as a deceptive tactic to attract females with fewer growth costs. If males possessing long tails would be cheater males, it is predicted that females would incur costs through mating with the males having long tails. In the present study, the costs incurred by females as a result of mating with males possessing proportionally long tails were examined. Females that had mated with males possessing long tails delivered fewer numbers of offspring than those that had mated with males possessing short tails. After maturation, daughters of males with long tails exhibited smaller body sizes and lower reproductive output than daughters of males having short tails. On the other hand, sons of the long-tailed males had greater total lengths on account of their longer tails as compared with sons of the short-tailed males. These results suggest that, by mating with males possessing long tails, females not only incur costs with respect to the decrease in growth and reproduction in their daughters but also obtain benefits in terms of sexual attractiveness of their sons. It is also conceivable that females might develop some counter-adaptations to minimize the costs of mating with males having long tails.