Geographic variation in the advertisement calls ofGekko geckoin relation to variations in morphological features: implications for regional population differentiation

Abstract

Geographic variations in vocalizations and morphological characteristics of the tokay gecko (Gekko gecko L.) complex were identified using subjects recorded and/or collected in China and Southeast Asia. Populations in south China and northeast Vietnam (the black tokay) were compared with those in Thailand, Laos and south Vietnam (the red tokay). Red tokays possess gray- or dark green-colored skin with brick red spots interspersed on the dorsum, while black tokays possess dark-green skin with black spots or spots of other colors except brick red. Each group produces advertisement calls which consist of distinct acoustic phases. In both groups the first call phase consists of a series of pulses and the second phase consists of a series of two-note syllables. Only red tokays produce a third phase consisting of single notes. Frequency modulation patterns were profoundly different for call elements produced between the two groups. Calls of the black but not red tokay exhibit intricate frequency modulated elements with silent periods between pulses in the first phase and between syllables in the second phase. In the red tokay little or no frequency modulation was observed and no silent intervals were found between pulses or syllables. For both groups the acoustics of the pulses produced in the first phase varied among animals, suggesting it may function for individual identification while the second phase appears to identify the group (red vs black tokay). Thus the tokay complex has become differentiated geographically not only in terms of morphological characteristics but also in terms of call acoustics.