Department of Biology, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain.
Ecology, Evolution, and Development Group, Doñana Biological Station, CSIC. E-41092 Seville, Spain.
Sci Rep. 2017 Jan 4;7:39739. doi: 10.1038/srep39739.
In heterogeneous environments, the capacity for colour change can be a valuable adaptation enhancing crypsis against predators. Alternatively, organisms might achieve concealment by evolving preferences for backgrounds that match their visual traits, thus avoiding the costs of plasticity. Here we examined the degree of plasticity in pigmentation of newt larvae (Lissotriton boscai) in relation to predation risk. Furthermore, we tested for associated metabolic costs and pigmentation-dependent background choice behaviour. Newt larvae expressed substantial changes in pigmentation so that light, high-reflecting environment induced depigmentation whereas dark, low-reflecting environment induced pigmentation in just three days of exposure. Induced pigmentation was completely reversible upon switching microhabitats. Predator cues, however, did not enhance cryptic phenotypes, suggesting that environmental albedo induces changes in pigmentation improving concealment regardless of the perceived predation risk. Metabolic rate was higher in heavily pigmented individuals from dark environments, indicating a high energetic requirement of pigmentation that could impose a constraint to larval camouflage in dim habitats. Finally, we found partial evidence for larvae selecting backgrounds matching their induced phenotypes. However, in the presence of predator cues, larvae increased the time spent in light environments, which may reflect a escape response towards shallow waters rather than an attempt at increasing crypsis.
在异质环境中，颜色变化的能力是一种有价值的适应能力，可以增强对捕食者的伪装。或者，生物可能通过进化出对与自身视觉特征相匹配的背景的偏好来实现伪装，从而避免可塑性的成本。在这里，我们研究了蝾螈幼虫（Lissotriton boscai）在与捕食风险相关的色素沉着方面的可塑性程度。此外，我们还测试了相关的代谢成本和色素沉着依赖的背景选择行为。蝾螈幼虫表现出显著的色素沉着变化，即在三天的暴露时间内，浅色、高反射环境会导致褪黑，而深色、低反射环境会导致色素沉着。在切换微生境时，诱导的色素沉着是完全可逆的。然而，捕食者的线索并没有增强隐蔽的表型，这表明环境反照率诱导的色素沉着变化可以提高隐蔽性，而不管感知到的捕食风险如何。来自深色环境的色素沉着较多的个体代谢率较高，这表明色素沉着需要大量的能量，这可能会对在暗淡环境中进行伪装的幼虫造成限制。最后，我们发现了一些证据表明幼虫会选择与诱导表型相匹配的背景。然而，在捕食者线索存在的情况下，幼虫会增加在浅色环境中停留的时间，这可能反映了一种向浅水区的逃避反应，而不是试图增加伪装效果。
