PDF(Pubmed)
Abstract：
Environmental heterogeneity poses a significant influence on the functional characteristics of species and communities at local scales. Environmental transition zones, such as at the savanna-forest borders, can act as regions of ecological tension when subjected to sharp variations in the microclimate. For ectothermic organisms, such as lizards, environmental temperatures directly influence physiological capabilities, and some species use different thermoregulation strategies that produce varied responses to local climatic conditions, which in turn affect species occurrence and community dynamics. In the context of global warming, these various strategies confer different types of vulnerability as well as risks of extinction. To assess the vulnerability of a species and understand the relationships between environmental variations, thermal tolerance of a species and community structure, lizard communities in forest-savanna transition areas of two national parks in the southwestern Amazon were sampled and their thermal functional traits were characterized. Then, we investigated how community structure and functional thermal variation were shaped by two environmental predictors (i.e., microclimates estimated locally and vegetation structure estimated from remote sensing). It was found that the community structure was more strongly predicted by the canopy surface reflectance values obtained via remote sensing than by microclimate variables. Environmental temperatures were not the most important factor affecting the occurrence of species, and the variations in ecothermal traits demonstrated a pattern within the taxonomic hierarchy at the family level. This pattern may indicate a tendency for evolutionary history to indirectly influence these functional features. Considering the estimates of the thermal tolerance range and warming tolerance, thermoconformer lizards are likely to be more vulnerable and at greater risk of extinction due to global warming than thermoregulators. The latter, more associated with open environments, seem to take advantage of their lower vulnerability and occur in both habitat types across the transition, potentially out-competing and further increasing the risk of extinction and vulnerability of forest-adapted thermoconformer lizards in these transitional areas.
摘要：
环境异质性在局部尺度上对物种和群落的功能特征产生重大影响。环境过渡带,比如在稀树草原森林的边界，当受到小气候的急剧变化时，可以充当生态紧张的区域。对于放热生物，比如蜥蜴,环境温度直接影响生理能力，一些物种使用不同的温度调节策略，对当地气候条件产生不同的反应，进而影响物种的发生和群落动态。在全球变暖的背景下,这些不同的策略赋予了不同类型的脆弱性以及灭绝的风险。为了评估物种的脆弱性并了解环境变化之间的关系，一个物种和群落结构的耐热性，对亚马逊西南部两个国家公园的森林-稀树草原过渡区的蜥蜴群落进行了采样，并对其热功能特征进行了表征。然后，我们调查了两个环境预测因子如何塑造群落结构和功能热变化(即，当地估计的微气候和遥感估计的植被结构）。发现通过遥感获得的冠层表面反射率值比通过微气候变量更强烈地预测了群落结构。环境温度不是影响物种发生的最重要因素，并且在生态热性状上的变化证明了在家庭一级的分类学层次结构中的模式。这种模式可能表明进化史有间接影响这些功能特征的趋势。考虑到热耐受范围和增温耐受性的估计，与温度调节器相比，热变形蜥蜴可能更脆弱，并且由于全球变暖而灭绝的风险更大。后者,更多与开放环境相关，似乎利用了它们较低的脆弱性，并在过渡期间发生在两种栖息地类型中，在这些过渡地区，适应森林的热变形蜥蜴可能会竞争激烈，并进一步增加灭绝和脆弱性的风险。
