Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
Department of Zoology, Nelson Mandela University, Port Elizabeth, South Africa.
Mol Ecol. 2019 Aug;28(16):3709-3721. doi: 10.1111/mec.15176. Epub 2019 Aug 6.
Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub-robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments.
干旱环境为研究适应进化的机制提供了理想的条件。高温和低水分供应是许多恒温动物（包括鸟类）的无情压力源；然而，鸟类在沙漠中生存下来。虽然生理适应可能涉及代谢表型，但潜在的机制（可塑性、遗传学）在很大程度上尚未确定。为了探索这一点，我们采用了一种种内方法，重点研究了一种在湿润到干旱梯度上驻留的物种，即卡鲁灌丛莺（Cercotrichas coryphaeus）。具体来说，我们整合了环境（气候和初级生产力）、生理（代谢率：衡量能量消耗的指标）、基因型（能量产生机制的遗传变异）和微生物组（参与从获取能量的食物中进行处理）的数据，以推断生理适应的机制。我们发现，能量生理表型和肠道微生物组组成的变化与环境特征以及能量代谢途径相关基因的变异有关。具体来说，我们确定了一小部分候选适应性基因，其中一些与相关生理表型有已知联系。我们的研究结果表明，与能量稳态和可能的微生物群落组成相关的基因对能量生理的选择压力可能有助于适应当地条件，并为在恶劣环境中观察到的高鸟类种内分化提供解释。
