Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA.
Proc Natl Acad Sci U S A. 2011 Jun 14;108(24):9893-8. doi: 10.1073/pnas.1014497108. Epub 2011 May 31.
Habitat loss and disease are main drivers of global amphibian declines, yet the interaction between them remains largely unexplored. Here we show that paradoxically, habitat loss is negatively associated with occurrence, prevalence, and infection intensity of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in amphibian populations in the tropics. At a large spatial scale, increased habitat loss predicted lower disease risk in amphibian populations across Costa Rica and eastern Australia, even after jointly considering the effect of potential biotic and abiotic correlates. Lower host-species richness and suboptimal microclimates for Bd in disturbed habitats are potential mechanisms underlying this pattern. Furthermore, we found that anthropogenic deforestation practices biased to lowlands and natural vegetation remaining in inaccessible highlands explain increased Bd occurrence at higher elevations. At a smaller spatial scale, holding constant elevation, latitude, and macroclimate, we also found a negative relationship between habitat loss, and both Bd prevalence and infection intensity in frog populations in two landscapes of the Brazilian Atlantic Forest. Our results indicate that amphibians will be disproportionately affected by emerging diseases in pristine environments, and that, paradoxically, disturbed habitats may act as shelters from disease, but only for the very few species that can tolerate deforestation. Thus, tropical amphibian faunas are threatened both by destruction of natural habitats as well as increased disease in pristine forests. To curb further extinctions and develop effective mitigation and restoration programs we must look to interactions between habitat loss and disease, the two main factors at the root of global amphibian declines.
生境丧失和疾病是全球两栖动物减少的主要驱动因素，但它们之间的相互作用在很大程度上仍未得到探索。在这里，我们表明，具有讽刺意味的是，生境丧失与热带地区两栖动物种群中真菌巴特拉科奇特里亚· dendritic 的发生、流行和感染强度呈负相关。在较大的空间尺度上，即使在共同考虑潜在生物和非生物相关因素的影响后，生境丧失的增加预示着哥斯达黎加和澳大利亚东部的两栖动物种群的疾病风险降低。在受干扰的栖息地中，宿主物种丰富度降低和微气候对 Bd 不利是这种模式的潜在机制。此外，我们发现，偏向低地的人为森林砍伐实践和高海拔地区无法进入的天然植被解释了较高海拔处 Bd 发生增加的原因。在较小的空间尺度上，在恒定海拔、纬度和大气候的情况下，我们还发现巴西大西洋森林两个景观中蛙类种群的生境丧失与 Bd 流行和感染强度之间存在负相关关系。我们的研究结果表明，在原始环境中，两栖动物将受到新兴疾病的不成比例的影响，而且，具有讽刺意味的是，受干扰的栖息地可能成为疾病的庇护所，但仅限于极少数能够耐受森林砍伐的物种。因此，热带两栖动物区系既受到自然栖息地破坏的威胁，也受到原始森林中疾病增加的威胁。为了遏制进一步的灭绝，并制定有效的缓解和恢复计划，我们必须着眼于生境丧失和疾病之间的相互作用，这是全球两栖动物减少的两个主要根源。
