Response to simultaneous dehydration and thermal stress in three species of Puerto Rican frogs

Abstract

The response to simultaneous temperature and dehydration stress was examined in three species of Puerto Rican frogs. Eleutherodactylus antillensis is found primarily in hot, arid grasslands at low altitudes. Eleutherodactylus portoricensis is restricted to cool, forested montane habitats above 300 m. Eleutherodactylus coqui occurs in both the lowlands and the highlands. The physiological tolerance of the frogs to temperature was measured at 20, 25, and 30°C at various levels of dehydration using an index derived from jumping performance. Although jump distance of fully hydrated E. antillensis was unaffected by temperature, this species tolerated significantly more dehydration at high temperatures than low. Eleutherodactylus portoricensis died at 30°C, but in this species both distance jumped and dehydration tolerance were unaffected by lower temperatures. Distance jumped by E. coqui increased with increasing temperature, but tolerance of dehydration remained unchanged. Eleutherodactylus coqui was less tolerant of high temperatures than E. antillensis but more tolerant than E. portoricensis.