Department of Biology, University of Nevada, 1664 N Virginia Street, Reno, NV 89557, USA.
Department of Biological Sciences, Quinnipiac University, Hamden, CT, USA.
Proc Biol Sci. 2019 Aug 14;286(1908):20191215. doi: 10.1098/rspb.2019.1215. Epub 2019 Jul 31.
As urban areas continue to expand globally, understanding how and why species respond to novel habitats becomes increasingly important. Knowledge of the mechanisms behind observed phenotypic changes in urban animals will enable us to better evaluate the impact of urbanization on current and future generations of wildlife. Physiological changes, such as those involved in the endocrine stress response, may allow individuals to inhabit and thrive in urbanized areas, but it is currently unknown how these changes arise in natural populations. In this study, we performed a four-way cross-foster experiment in free-living house wren chicks, Troglodytes aedon, to disentangle whether differences in baseline corticosterone between urban and rural individuals are a result of genetic and/or plastic mechanisms during development. We found that urban chicks already had higher corticosterone levels than their rural counterparts on the day they hatched, which suggests a possible genetic component to the corticosterone phenotype. However, rural offspring that were moved to an urban environment significantly increased their corticosterone levels, mimicking those of urban offspring. Our findings suggest that, although differences in baseline corticosterone concentrations between urban and rural individuals may have a genetic component, plasticity plays a pivotal role and can modify the corticosterone phenotype in response to the environment experienced in the first two weeks of life.
随着全球城市面积的不断扩大，了解物种如何以及为何对新栖息地产生反应变得越来越重要。了解城市动物观察到的表型变化背后的机制将使我们能够更好地评估城市化对当前和未来几代野生动物的影响。生理变化，如参与内分泌应激反应的变化，可能使个体能够在城市化地区栖息和茁壮成长，但目前尚不清楚这些变化在自然种群中是如何产生的。在这项研究中，我们在自由生活的画眉雏鸟（Troglodytes aedon）中进行了四向交叉寄养实验，以厘清城市和农村个体之间基础皮质醇差异是发育过程中遗传和/或可塑性机制的结果。我们发现，城市雏鸟在孵化当天的皮质醇水平已经高于农村雏鸟，这表明皮质醇表型可能存在遗传成分。然而，被转移到城市环境的农村后代的皮质醇水平显著升高，模仿了城市后代的水平。我们的研究结果表明，尽管城市和农村个体之间基础皮质醇浓度的差异可能具有遗传成分，但可塑性起着关键作用，可以根据生命前两周经历的环境来改变皮质醇表型。
