Anuran survival is strongly affected by exposure to high environmental temperatures. However, their upper thermal tolerances vary between species and within developmental stages. The aims of this research were to measure the median lethal temperature (LT50) of three anuran developmental stages (Gosner stages 10, 20, and 25) at a constant thermal regime, and of developing embryos (stage 10) until they became tadpoles (stage 25) exposed to daily peaks of temperatures between 1000 and 1600. Four Colombian species (Emerald-eyed Treefrog, Hypsiboas crepitans (Wied-Neuwied, 1824); Tungara Frog, Engystomops pustulosus (Cope, 1864); Rivero’s Toad, Rhinella humboldti (Gallardo, 1965); Emerald Glassfrog, Espadarana prosoblepon (Boettger, 1892)) were used in these experiments. An ontogenetic increase was observed in the upper thermal tolerance from embryos to tadpoles for all species studied. In addition, developing embryos exposed to peak temperatures showed a LT50 fairly close to the mean of the maximum habitat temperatures, particularly in H. crepitans and E. pustulosus that lay egg masses exposed directly to the sun. Environmental temperatures in the microhabitat of species studied showed values remarkably higher than their experimental LT50. Therefore, we postulate that rapid increases in environmental temperatures, as result of global or local changes, might be a critical factor for anuran survival, mainly during the embryonic stages when they are more sensitive to temperature.

Using two populations of Aegla araucaniensis, one syntopic with two congeneric species (A. abtao and A. denticulata) and the other no, we assessed agonistic behavioural variations associated with interspecific competition (type of interaction, intensity of aggression, and frequency of dominance in two-and three-species encounters). In general, there was a low level of aggression among interacting individuals. The frequency of agonistic responses tended significantly towards more aggressive behaviours in A. araucaniensis that are not naturally exposed to interspecific competition compared with those that are. The competitive hierarchy was dominated by A. abtao, followed by both populations of A. araucaniensis. Aegla denticulata was always the subordinate species. We can conclude that: (1) the dominance hierarchy is coherent with the distribution patterns of the species in their natural habitat; (2) unlike other species of freshwater decapods, the nature of the studied aeglids is fundamentally passive; (3) in A. araucaniensis, interspecific competition can generate changes in the expression of behavioural traits; (4) in decapod crustaceans, the hierarchies of dominance may be established by conditions other than fighting abilities and/or intensity of agonistic interactions.