Antarctic marine biology

David K.A. Barnes and Andrew Clarke Primer interfering with the ability of a second species to locate mates. This could be the result of the one species’ calls simply masking those of the other, or it could be that the calls confuse individuals of the second species and cause them to approach heterospecific callers rather than those of their own species. Such signal jamming can also occur within a sex. For instance, among two species of Amazonian frog, there is selection for decreased sensitivity in male Allobates femoralis to calls that fall within the range of Epipedobates trivittatus calls in areas where the two species overlap (Figure 1). That way A. femoralis might avoid interference resulting from the overlapping frequency range of E. trivittatus calls. As these calls form the basis of male–male communication in these territorial frogs, responses to E. trivittatus calls by A. femoralis males could represent both signal jamming and heterospecific rivalry.