Eterovick Paula C, Bar Luís F F, Souza Jorge B, Castro José F M, Leite Felipe S F, Alford Ross A
Programa de Pós Graduação em Zoologia de Vertebrados, Pontifícia Universidade Católica de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Programa de Pós Graduação em Geografia-Tratamento da Informação Espacial, Pontifícia Universidade Católica de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
PLoS One. 2015 Mar 20;10(3):e0120172. doi: 10.1371/journal.pone.0120172. eCollection 2015.
Amphibian population declines are widespread; the main causal factors are human related and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction, but there are presently relatively few reports of amphibian declines. It is thus important to develop research methods that will detect deterioration in population health before severe declines occur. We tested the use of measurements of fluctuating asymmetry (FA) taken on amphibian larvae to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians. We conducted this study at the Espinhaço mountain range in southeastern Brazil, using as a model an endemic species (Bokermannohyla saxicola, Hylidae). We chose two tadpole denticle rows and eye-nostril distance as traits for FA measurement. We measured percent cover of human-altered habitats in the landscape around tadpole sampling points and measured FA levels in sampled tadpoles. We found FA levels to differ among localities but found no relationship between human modification of the landscape and tadpole FA levels. Levels of FA in the traits we examined may not be strongly affected by environmental conditions, or may be affected by local variables that were not captured by our landscape-scale measures. Alternatively, populations may be genetically differentiated, affecting how FA levels respond to stress and obscuring the effects of anthropogenic disturbance.
两栖动物数量的减少十分普遍；主要成因与人类相关，包括农业、采矿、火灾和城市发展导致的栖息地破碎化。巴西是两栖动物物种最为丰富的国家，两栖动物多样性最高的巴西地区正经历着相对较高程度的栖息地破坏，但目前关于两栖动物数量减少的报道相对较少。因此，开发能够在两栖动物数量严重减少之前检测出其种群健康状况恶化的研究方法至关重要。我们测试了通过测量两栖动物幼体的波动不对称性（FA）来检测人为压力的方法。我们假设，人类在该地区的活动增加可能会给两栖动物带来更多压力。我们在巴西东南部的埃斯皮尼亚苏山脉开展了这项研究，以一种特有物种（岩栖博克蛙，雨蛙科）作为研究对象。我们选择了蝌蚪的两排小齿以及眼鼻间距作为测量波动不对称性的特征。我们测量了蝌蚪采样点周围景观中人类改变后的栖息地的覆盖百分比，并测量了所采集蝌蚪的波动不对称性水平。我们发现不同地点的波动不对称性水平存在差异，但未发现景观的人类改造与蝌蚪的波动不对称性水平之间存在关联。我们所研究特征的波动不对称性水平可能不受环境条件的强烈影响，或者可能受到我们的景观尺度测量未涵盖的局部变量的影响。另外，不同种群可能在基因上存在差异，这会影响波动不对称性水平对压力的反应方式，并掩盖人为干扰的影响。
