Abstract:
Understanding the evolution of adaptive plasticity is fundamental to our knowledge of how organisms interact with their environments and cope with environmental change. Plasticity in melanin pigmentation is common in response to variable environments, especially thermal environments. Yet, the adaptive significance of melanin plasticity in thermally variable environments is often assumed, but rarely explicitly tested. Furthermore, understanding the role of plasticity when a trait is responsive to multiple environmental stimuli and plays many functional roles remains poorly understood. We test the hypothesis that melanin plasticity is an adaptation for thermally variable environments using Hyles lineata, the white-lined sphinx moth, which shows plasticity in melanin pigmentation during the larval stage. Melanin pigmentation influences thermal traits in H. lineata, as melanic individuals had higher heating rates and reached higher body temperatures than non-melanic individuals. Importantly, melanin pigmentation has temperature specific fitness consequences. While melanic individuals had an advantage in cold temperatures, neither phenotype had a clear fitness advantage at warm temperatures. Thus, the costs associated with melanin production may be unrelated to thermal context. Our results highlight the importance of explicitly testing the adaptive role of plasticity and considering all the factors that influence costs and benefits of plastic phenotypes across environments.
摘要:
了解适应性可塑性的进化是我们了解生物体如何与其环境相互作用并应对环境变化的基础。黑色素色素沉着的可塑性在变化的环境中很常见,特别是热环境。然而,黑色素可塑性在热变环境中的适应性意义通常被认为,但很少明确测试。此外,理解可塑性的作用,当一个性状响应多种环境刺激,并发挥许多功能的作用,仍然知之甚少。我们使用Hyleslineata检验了黑色素可塑性是对热变环境的适应性的假设,白色衬里的狮身人面像蛾,在幼体阶段显示黑色素色素沉着的可塑性。黑色素色素沉着影响H.lineata的热性状,因为黑色素个体比非黑色素个体具有更高的加热速率并达到更高的体温。重要的是,黑色素沉着具有温度特定的健身后果。虽然黑色素个体在寒冷的温度下有优势,两种表型在温暖温度下都没有明显的适应性优势。因此,与黑色素生产相关的成本可能与热环境无关。我们的结果强调了明确测试可塑性的适应性作用并考虑影响跨环境塑料表型成本和收益的所有因素的重要性。