Diversity and associations between coastal habitats and anurans in southernmost Brazil

This study aimed to verify the relationship between habitat and the composition of anuran species in dune and restinga habitats in southernmost Brazil. The habitats were sampled between April 2009 and March 2010 using pitfalls with drift fence. We have captured 13,508 individuals of 12 anuran species. Species richness was lower in the dunes and dominance was higher in the resting. Apparently the less complex plant cover, water availability, and wide daily thermal variation in dunes act as an environmental filter for frogs. This hypothesis is reinforced by the fact that the most abundant species (Physalaemus biligonigerus and Odonthoprynus maisuma) bury themselves in the sand, minimizing these environmental stresses. Despite being in the Pampa biome, the studied community was more similar to those of coastal restinga environment of southeast Brazil than with other of the Pampa biome. The number of recorded species is similar to those observed in other open habitats in Brazil, showing the importance of adjacent ones to the shoreline for the maintenance of the diversity of anurans in southernmost Brazil.本研究旨在验证巴西南部最南端区域内，沙丘生境与海滨沙生生境（restinga）中无尾两栖类（anuran）物种组成与生境的关联。研究于2009年4月至2010年3月间，采用带有漂移拦截围栏的陷阱法（pitfalls with drift fence）开展采样，共捕获12种无尾两栖类共计13508只个体。结果显示，沙丘生境的物种丰富度更低，而海滨沙生生境的物种优势度更高。显然，沙丘生境中植物覆盖度较低、水资源可获得性不足且昼夜温差剧烈，这些因素共同构成了制约蛙类生存的环境过滤屏障。该假说可得到如下事实的佐证：丰度最高的两个物种（Physalaemus biligonigerus与Odonthoprynus maisuma）可通过埋身沙中，最大程度抵消此类环境胁迫带来的影响。尽管研究区域属于潘帕斯生物群区（Pampa biome），但本次研究的两栖类群落与巴西东南部沿海海滨沙生生境的群落更为相似，而非该生物群区内的其他群落。本次记录的物种数量与巴西境内其他开阔生境中观测到的物种数量相当，这表明紧邻海岸线的生境对于维持巴西南部最南端地区无尾两栖类的多样性具有重要意义。