Abstract:
Animals often use multicomponent signals in intraspecific communication to convey sexual information such as sex identity and quality of the signaler. In the day gecko Cnemaspis mysoriensis, two chemical components, squalene and cholesterol, are present in the femoral and precloacal gland secretions of males, but are absent in females. This multicomponent signal provides an opportunity to understand the function of each component of a complex signal. I quantified receiver responses towards squalene and cholesterol when presented individually and in combination. The tongue flick assay revealed that females, but not males, showed an elevated response towards squalene and cholesterol, as individual components and together. Females also showed increase in tongue flick response with the increase in squalene and cholesterol stimuli concentrations. I further examined female preferences towards natural male secretions in a Y-tube choice experiment. Female choice revealed that secretions of males with low ectoparasite load and high sprint speed were preferred. Based on the receiver tongue flick responses and female choices, I conclude that: 1) squalene and cholesterol independently and together act as sex recognition signals of males in this species, 2) females are able to differentiate between conspecific males based on squalene and cholesterol concentrations and 3) male secretion components also contribute in mate assessment and females prefer males with low ectoparasite load and high sprint speed.
Description:
This body of work was carried out as a part of MS dissertation project at IISc Bangalore. Results of the study highlight the efficiency and complexity of chemical signalling in animals, which is historically understudied as compared to more conspicuous visual and acoustic signals. This work, for the first time, looks at functions of individual signal components of a complex chemical signal in sexual communication. This is important for better understanding of animal communication and signal trait evolution. The work is also a rare account of such behavioral and mate choice studies in small diurnal geckos.
