Anolis signals & species recognition

Visual signalling is used during inter and intra specific interactions, and has evolved toward complex, diverse and highly species-specific displays. Its evolution seems to beinfluenced by several factors including the presence of conspecifics. Moreover, in complex assemblages, species are predicted to segregate in time or space. For instance,variation in the signal could reinforce species identity and reduce unnecessary competition. Anolis lizards communicate by using highly specific displays during which a coloured structure, called a dewlap, is exhibited. We studied signalling of several mainland anoles from South America to test the species recognition hypothesis. We expected intra-population variation of the signal, and anticipated that such variation favours differentiation against sympatric congeners. We found significant differences in the colour of the dewlap and the display between assemblages of the focal species (A. fuscoauratus), however such changes are not influenced by congeners, but may be necessary for species recognition. Some parameters, of both colour of the dewlap and motion of the display, remain uniform across assemblages. The results provide evidence to suggest that the visual signals of Anoles is highly important for species recognition in sympatric assemblages. Nevertheless, alternative hypothesis such as local selection, sexual selection or genetic drift remain to be tested to explain intra specific variation.
Figure | composition of Anolis assemblages: single (one species), small (three species) and large (six species) assemblages.