Evolutionary novelty in chemical signalling is linked with chemosensory behaviour in close Liolaemus lizard species (Iguania: Liolaemidae)

Abstract

Evolutionary changes, associated with the gain or loss of traits, can occur insignal-emitting and signal-detecting organs. Related functionality generally accompaniesthese changes; however, in some cases there are mismatches and evolutionaryinnovations do not show an indication of functional advantages. Due to this,the relationship between evolutionary changes and the functionality of sensoryorgans remains unclear. Lizard species belonging to Liolaemus lineomaculatus sectionpresent fast evolutionary state transitions associated with the gain or loss ofprecloacal pores (chemical signalling glands). In this group, precloacal pores configurationincludes species where only males have pores (Liolaemus attenboroughiancestralstate), where both sexes lack of them (L. kolengh male-loss), and specieswhere both sexes have pores (L. zullyae, representing a female-gain). Here, we testthe relationships between evolutionary changes of signal-emitting glands with differentchemical and visual behaviours. We conducted behavioural trials in threespecies belonging to the Liolaemus lineomaculatus section: L. attenboroughi,L. kolengh, and L. zullyae. We measured individuals’ chemical and visual responsesto different social scents and to conspecific visual stimuli. Results showed the presenceof different social scents recognition ability in both male-only andfemale-gain species, whereas male-loss species showed no behavioural differencesamong the chemical trials. Lizards exhibited few responses in the visual trials,although the species with pores used chemo-sensorial sense in the visual trials,while male-loss species showed differences in visual displays in the presence ofconspecific visual stimuli. These results suggest a link between evolutionary noveltiesof chemical secretory glands and chemical recognition.