Titon Braz, Gomes Fernando Ribeiro
Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
Comp Biochem Physiol A Mol Integr Physiol. 2017 Jun;208:54-60. doi: 10.1016/j.cbpa.2017.03.012. Epub 2017 Mar 21.
Interspecific variation in patterns of geographical distribution of phylogenetically related species of amphibians might be related to physiological adaptation to different climatic conditions. In this way, a comparative study of resistance to evaporative water loss, rehydration rates and sensitivity of locomotor performance to variations on hydration level and temperature was performed for five species of Bufonidae toads (Rhinella granulosa, R. jimi, R. ornata, R. schneideri and R. icterica) inhabiting different Brazilian biomes. The hypotheses tested were that, when compared to species inhabiting mesic environments, species living at hot and dry areas would show: (1) greater resistance to evaporative water loss, (2) higher rates of water uptake, (3) lower sensitivity of locomotor performance to dehydration and (4) lower sensitivity of locomotor performance at higher temperatures and higher sensitivity of locomotor performance at lower temperatures. This comparative analysis showed relations between body mass and interspecific variation in rehydration rates and resistance to evaporative water loss in opposite directions. These results might represent a functional compensation associated with relatively lower absorption areas in larger toads and higher evaporative areas in smaller ones. Moreover, species from the semi-arid Caatinga showed locomotor performance less sensitive to dehydration but highly affected by lower temperatures, as well greater resistance to evaporative water loss, when compared to the other species from the mesic Atlantic Forest and the savannah-like area called Cerrado. These results suggest adaptation patterns to environmental conditions.
两栖动物系统发育相关物种地理分布模式的种间差异可能与对不同气候条件的生理适应有关。通过这种方式，对栖息于巴西不同生物群落的五种蟾蜍科蟾蜍（粒疣蟾蜍、吉米蟾蜍、饰纹蟾蜍、施氏蟾蜍和黄斑蟾蜍）进行了蒸发失水抗性、补水速率以及运动表现对水分含量和温度变化的敏感性的比较研究。所检验的假设是，与栖息于湿润环境的物种相比，生活在炎热干燥地区的物种会表现出：（1）对蒸发失水的抗性更强，（2）吸水速率更高，（3）运动表现对脱水的敏感性更低，以及（4）在较高温度下运动表现的敏感性更低，而在较低温度下运动表现的敏感性更高。这种比较分析表明，体重与补水速率和蒸发失水抗性的种间差异呈相反方向的关系。这些结果可能代表了一种功能补偿，与较大蟾蜍相对较小的吸收面积和较小蟾蜍较高的蒸发面积有关。此外，与来自湿润的大西洋森林和类似热带稀树草原的塞拉多地区的其他物种相比，来自半干旱卡廷加地区的物种运动表现对脱水的敏感性较低，但受低温影响较大，且对蒸发失水的抗性更强。这些结果表明了对环境条件的适应模式。
