LITORIA-EWINGI COMPLEX (ANURA-HYLIDAE) IN SOUTHEASTERN AUSTRALIA .4. VARIATION IN MATING-CALL STRUCTURE ACROSS A NARROW HYBRID ZONE BETWEEN LITORIA-EWINGI AND LITORIA-PARAEWINGI

The presence of mating calls characteristic of both parental species, and of intermediate calls, within the zone of contact between L. ewingi and L. paraewingi supports the earlier interpretation that the interaction is an overlap with hybridization. Pulse repetition rates are similar throughout the transect, and there are no clear indications of reproductive character displacement within the hybrid zone, even though marked one-way genetic incompatibility is present. Calls from close allopatry are more distinctive than those from distant allopatry, mainly in pulses per repeated note (a meristic character reflecting differences in note duration), suggesting that the effects of reinforcing selection may be accumulating in the proximity of the zone of interaction.