Brady Steven P
School of Forestry & Environmental Studies, Yale University, 370 Prospect Street, New Haven, CT, 06511, USA.
Biology Department, Southern Connecticut State University, New Haven, CT, 06515, USA.
Oecologia. 2017 Aug;184(4):931-942. doi: 10.1007/s00442-017-3912-6. Epub 2017 Jul 17.
While the ecological consequences of roads are well described, little is known of their role as agents of natural selection, which can shape adaptive and maladaptive responses in populations influenced by roads. This knowledge gap persists despite a growing appreciation for the influence of evolution in human-altered environments. There, insights indicate that natural selection typically results in local adaptation. Thus, populations influenced by road-induced selection should evolve fitness advantages in their local environment. Contrary to this expectation, wood frog tadpoles from roadside populations show evidence of a fitness disadvantage, consistent with local maladaptation. Specifically, in reciprocal transplants, roadside populations survive at lower rates compared to populations away from roads. A key question remaining is whether roadside environmental conditions experienced by early stage embryos induce this outcome. This represents an important missing piece in evaluating the evolutionary nature of this maladaptation pattern. Here, I address this gap using a reciprocal transplant experiment designed to test the hypothesis that embryonic exposure to roadside pond water induces a survival disadvantage. Contrary to this hypothesis, my results show that reduced survival persists when embryonic exposure is controlled. This outcome indicates that the survival disadvantage is parentally mediated, either genetically and/or through inherited environmental effects. This result suggests that roadside populations are either truly maladapted or potentially locally adapted at later life stages. I discuss these interpretations, noting that regardless of mechanism, patterns consistent with maladaptation have important implications for conservation. In light of the pervasiveness of roads, further resolution explaining maladaptive responses remains a critical challenge in conservation.
虽然道路对生态的影响已有详尽描述，但对于其作为自然选择因素所起的作用却知之甚少，而自然选择能够塑造受道路影响的种群中的适应性和非适应性反应。尽管人们越来越认识到进化在人类改变的环境中的影响，但这一知识空白依然存在。在那里，有见解表明自然选择通常会导致局部适应。因此，受道路诱导选择影响的种群应该在其当地环境中进化出适应优势。与这一预期相反，来自路边种群的林蛙蝌蚪显示出适应性劣势的证据，这与局部适应不良一致。具体而言，在相互移植实验中，路边种群的存活率低于远离道路的种群。剩下的一个关键问题是，早期胚胎所经历的路边环境条件是否会导致这一结果。这是评估这种适应不良模式的进化本质中一个重要的缺失环节。在此，我通过一项相互移植实验来填补这一空白，该实验旨在检验胚胎暴露于路边池塘水会导致生存劣势这一假设。与该假设相反，我的结果表明，当控制胚胎暴露时，存活率降低的情况依然存在。这一结果表明，生存劣势是由亲代介导的，可能是通过基因和/或遗传环境效应。这一结果表明，路边种群要么真的适应不良，要么可能在生命后期局部适应。我讨论了这些解释，并指出无论机制如何，与适应不良一致的模式对保护具有重要意义。鉴于道路的普遍性，进一步解释适应不良反应仍然是保护工作中的一项关键挑战。
