Sexual selection and communication in the African painted reed frog (Hyperolius marmoratus)

The evolution of female mate choice and male sexual displays is of continuing interest to behavioral ecologists. In this study I report on sexual selection and communication in an anuran with a lek mating system, the African painted reed frog (Hyperolius marmoratus broadleyi). Specifically, the focus of my research has been: (1) to understand the criteria used by female reed frogs in choosing a male within the complex acoustic conditions of small natural choruses, (2) to determine if females obtain any direct benefits from being choosy, and (3) to examine how male acoustic display behaviors might enhance male reproductive success. In addition, I examine male and female reproductive energetics and the physiological and energetic constraints on male mating effort.;The potential reproductive rate was higher in males than females. This is consistent with the observed male-biased operational sex ratio. Males spent a median of 1.5 nights at the chorus, or 8.3% of the observation period. This abbreviated chorus tenure is probably caused, in part, by energetic constraints experienced by males. Calling is energetically expensive. Oxygen consumption increased linearly with call rate and reached 0.91 ml/g;Male reed frogs have graded aggressive calls. Playback experiments showed that males increased the proportion of aggressive calls as well as three call characteristics as the stimulus intensity was increased. Females discriminated against aggressive calls, suggesting that aggressive calls mediate male-male interactions. Males were shown to alternate advertisement calls with neighboring males. One function of call alternation is to make calls more easily locatable to females.;Two potential direct benefits that females might gain from being choosy were investigated: assurance of fertilization and reduction of search costs. Females did not benefit by gaining higher rates of fertilization. However, costs of mate searching were high due to predation risk by water snakes. Females preferred males that were near to their release site and which called at high rates. These preferences are consistent with the notion that females should reduce search time. High sampling costs make direct selection on female preferences a plausible solution to the lek paradox.