Farji-Brener Alejandro G, Elizalde Luciana, Fernández-Marín Hermógenes, Amador-Vargas Sabrina
Laboratorio Ecotono, INIBIOMA-CONICET, Pasaje Gutiérrez 1125, 8400 Bariloche, Argentina
Laboratorio Ecotono, INIBIOMA-CONICET, Pasaje Gutiérrez 1125, 8400 Bariloche, Argentina.
Proc Biol Sci. 2016 May 25;283(1831). doi: 10.1098/rspb.2016.0625.
Adequate waste management is vital for the success of social life, because waste accumulation increases sanitary risks in dense societies. We explored why different leaf-cutting ants (LCA) species locate their waste in internal nest chambers or external piles, including ecological context and accounting for phylogenetic relations. We propose that waste location depends on whether the environmental conditions enhance or reduce the risk of infection. We obtained the geographical range, habitat and refuse location of LCA from published literature, and experimentally determined whether pathogens on ant waste survived to the high soil temperatures typical of xeric habitats. The habitat of the LCA determined waste location after phylogenetic correction: species with external waste piles mainly occur in xeric environments, whereas those with internal waste chambers mainly inhabit more humid habitats. The ancestral reconstruction suggests that dumping waste externally is less derived than digging waste nest chambers. Empirical results showed that high soil surface temperatures reduce pathogen prevalence from LCA waste. We proposed that LCA living in environments unfavourable for pathogens (i.e. xeric habitats) avoid digging costs by dumping the refuse above ground. Conversely, in environments suitable for pathogens, LCA species prevent the spread of diseases by storing waste underground, presumably, a behaviour that contributed to the colonization of humid habitats. These results highlight the adaptation of organisms to the hygienic challenges of social living, and illustrate how sanitary behaviours can result from a combination of evolutionary history and current environmental conditions.
适当的废物管理对于社会生活的成功至关重要，因为在人口密集的社会中，废物堆积会增加卫生风险。我们探究了为什么不同种类的切叶蚁将它们的废物放置在巢穴内部腔室或外部堆积处，这包括生态背景并考虑了系统发育关系。我们提出，废物放置位置取决于环境条件是增加还是降低感染风险。我们从已发表的文献中获取了切叶蚁的地理分布范围、栖息地和废物放置位置，并通过实验确定了蚁类废物上的病原体是否能在干旱栖息地典型的高土壤温度下存活。经过系统发育校正后，切叶蚁的栖息地决定了废物放置位置：有外部废物堆积的物种主要出现在干旱环境中，而有内部废物腔室的物种主要栖息在湿度更高的栖息地。祖先重建表明，在外部倾倒废物比挖掘废物巢穴腔室的进化程度更低。实证结果表明，高土壤表面温度会降低切叶蚁废物中的病原体流行率。我们提出，生活在不利于病原体生存的环境（即干旱栖息地）中的切叶蚁通过在地面上倾倒垃圾来避免挖掘成本。相反，在适合病原体生存的环境中，切叶蚁物种通过将废物储存在地下以防止疾病传播，据推测，这种行为有助于它们在潮湿栖息地的定殖。这些结果突出了生物体对社会生活卫生挑战的适应性，并说明了卫生行为是如何由进化历史和当前环境条件共同作用产生的。
