Islands are natural laboratories for evolutionary studies due to their small areas, structural complexity (compared to continents), and their different degrees of isolation. The present study involved four distinct areas, one continental and three insular, on the southern coast of the State of Rio de Janeiro, Brazil. These islands were formed by coastal flooding at the end of the last glacial maximum, approximately 10 thousand years ago. We investigated acoustic parameters in the advertisement call of the green tree frog, Aplastodiscus eugenioi (Hylidae), looking for variations that could be associated with geographic isolation in the insular populations. We measured six acoustic parameters of the advertisement calls of 59 males, 15 specimens from the continent and 44 from the islands. We found significant variation in acoustic parameters within the population from ***Ilha de Itacuruçá, suggesting that isolation, despite the relatively short period, favored differentiation of acoustical parameters. In fact, call evolution may involve a series of changes in both females and males in a synchronous way, so that the signal producer and receiver can behave accordingly for successful reproduction.