Does social behaviour reliably reflect temperature-dependent physiological capacity in geckos?

Abstract

Animals with low energy budgets may attempt to deceive their opponents during contests by producing social displays that falsely indicate their physiological state. We used overnight laboratory experiments to examine the relation between physiological capacity and social behaviour in a nocturnal gecko. Velvet geckos, Oedura lesueurii, use loose surface rocks that vary considerably in temperature as diurnal retreat sites. At night males defend retreat sites and the outcomes of contests are resolved via physical duels. We manipulated a gecko's physiological state at night by allocating geckos to diurnal retreat sites with different thermal regimes. At night geckos from colder diurnal retreat sites were less mobile, and had poorer locomotor performance, than conspecifics from warmer diurnal retreat sites. We hypothesized that such differences in physiological capacity would be reflected in outcomes of territorial contests between pairs of adult males. However, geckos from colder diurnal retreat sites were just as likely to win nocturnal contests for a limited resource as were geckos from warmer diurnal retreat sites. This result may reflect differences in the behaviour of geckos with different thermal exposure. Geckos from colder diurnal retreat sites were significantly more aggressive during contests than conspecifics from warmer diurnal retreat sites. Thus, animals may attempt to deceive opponents by producing a social display that vastly overstates their current physiological state.