Influence of advertisement calls on reproductive success in the male midwife toad Alytes obstetricans

Considering the advertisement call in anuran as a sexually selected trait, we investigated the effects of male call parameters on reproductive success in midwife toad Alytes obstetricans. The pattern of advertisement call was studied in 81 males. The mean fundamental frequency varied among males. Fundamental frequency, call duration and male size correlated with the male mating success. From the stepwise regression analysis, the low call frequency was found to influence significantly the number of carried eggs and the hatching success. The fact that a single male may fertilise the eggs of several females and a single female may mate with several males constitutes an original sexual system. Large males obtained more matings and showed a higher hatching success. Female choice for dominant frequency may be regarded as a related-fitness trait being correlated with male size. Anyway, the mate size and the female choice for low calls result in a same evolutionary trend favouring a best fitness.