The jumping performance of two Eleutherodactylus frog species: the effect of temperature

Abstract

This study was undertaken to understand the species-specific response and the effect of changes in ambient temperature on the jumping performance of two congeneric tropical frog species, environmental specialist Eleutherodactylus wightmanae and environmental generalist Eleutherodactylus coqui, obtained from three distinct populations across their east-west longitudinal range in Puerto Rico. Three environmental temperatures currently experienced in their natural habitat were selected for treatments: 18 °C, 21 °C, and 24 °C. Jumping performance was determined by the average distance traveled per jump and the average speed per jump based on three consecutive jumps. A significant increase in distance per jump was observed in both species with the temperature treatment of 24 °C, resulting in the longest jump. On average, the specialist Eleutherodactylus wightmanae outperformed the generalist Eleutherodactylus coqui, but the effect was largely affected by temperature treatment and location. At a population level, individuals of both species obtained from the Toro Negro Forest jumped farther than individuals from Maricao and Cayey. Speed per jump was not affected by temperature treatments; instead, differences in speed were observed at the population (i.e. locality) and species level. Individuals of Eleutherodactylus coqui obtained from the Cayey Forest were significantly slower than all other sites in all treatments. In contrast, individuals of Eleutherodactylus wightmanae from the Maricao Forest were slowest in all treatments. The study provides evidence of the species-specific response to increases in temperature and the local adaptation capabilities and thermal plasticity observed across the longitudinal range for two frog species of Puerto Rico. The study also reinstates multifactorial aspects concerning anuran physiology and how biotic conditions affect their performance.