Meeting Abstract
The marine toad Rhinella marina, or cane toad, has been introduced to over 40 countries. One major invasion in Australia has resulted in the rapid expansion of the range and numbers of toads leading to a potential major loss of biological diversity. Studies on the Cane Toad in Australia has demonstrated rapid evolution in limb length, locomotor performance, critical thermal minimum (CTmin), and behavior. Surprisingly, a limited amount of information is available on the same traits for Cane Toads in their native range. Here we present the results from a study designed to examine the consequences of temperature and hydration on locomotor performance in Cane Toads. We also present data on CTmin, rates of water loss and water uptake, and limb lengths. We captured 18 R. marina at Chamela Biological Station, which is situated at an elevation of ~500m. We measured locomotor performance (distance jumped for 10 minutes) at three temperatures (25, 30, 35°C ) and four hydration levels (100, 90, 80, and 70%). Locomotor performance increased with temperature, but declined with hydration level. CTmin was 7.32°C and 8.3°C for females and males, respectively. We found that locomotor performance of Chamela toads exceeded that of Australian toads at each level of hydration. CTmin values for R. marina in Mexico overlapped the values for cane toads at low elevations in Australia (7·5°C). Water loss and water uptake rates were also similar between Mexico and Australian toads. Our results demonstrate a striking decline in locomotor performance in Australian toads. However, our results re-enforce the observation of rapid evolution of physiological traits in an invasive species.
