Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
Curr Biol. 2018 Apr 23;28(8):1325-1329.e2. doi: 10.1016/j.cub.2018.03.022. Epub 2018 Apr 12.
The canonical drivers of population genetic structure, or spatial genetic variation, are isolation by distance and isolation by environment. Isolation by distance predicts that neighboring populations will be genetically similar and geographically distant populations will be genetically distinct [1]. Numerous examples also exist of isolation by environment, a phenomenon in which populations that inhabit similar environments (e.g., same elevation, temperature, or vegetation) are genetically similar even if they are distant, whereas populations that inhabit different environments are genetically distinct even when geographically close [2-4]. These dual models provide a widely accepted conceptual framework for understanding population structure [5-8]. Here, we present evidence for an additional, novel process that we call isolation by navigation, in which the navigational mechanism used by a long-distance migrant influences population structure independently of isolation by either distance or environment. Specifically, we investigated the population structure of loggerhead sea turtles (Caretta caretta) [9], which return to nest on their natal beaches by seeking out unique magnetic signatures along the coast-a behavior known as geomagnetic imprinting [10-12]. Results reveal that spatial variation in Earth's magnetic field strongly predicts genetic differentiation between nesting beaches, even when environmental similarities and geographic proximity are taken into account. The findings provide genetic corroboration of geomagnetic imprinting [10, 13]. Moreover, they provide strong evidence that geomagnetic imprinting and magnetic navigation help shape the population structure of sea turtles and perhaps numerous other long-distance migrants that return to their natal areas to reproduce [13-17].
人口遗传结构（或空间遗传变异）的典型驱动因素包括地理隔离和生态隔离。地理隔离预测，相邻的种群在遗传上是相似的，而地理上遥远的种群在遗传上是不同的[1]。也有许多关于生态隔离的例子，即当居住在相似环境（如相同海拔、温度或植被）的种群即使相距很远，它们在遗传上也很相似，而当居住在不同环境中的种群即使在地理上很接近时，它们在遗传上也很不同[2-4]。这两种模型为理解种群结构提供了一个广泛接受的概念框架[5-8]。在这里，我们提出了另一种新的隔离机制的证据，我们称之为导航隔离，即长距离迁徙者所使用的导航机制，独立于距离或环境隔离，影响种群结构。具体来说，我们调查了红海龟（Caretta caretta）的种群结构[9]，它们通过沿着海岸寻找独特的磁场特征来寻找回巢的路径，这种行为被称为地磁印记[10-12]。结果表明，地球磁场的空间变化强烈预测了筑巢海滩之间的遗传分化，即使考虑到环境相似性和地理接近性。这些发现为地磁印记提供了遗传证据[10,13]。此外，它们提供了强有力的证据表明，地磁印记和磁性导航有助于塑造海龟的种群结构，也许还有许多其他返回出生地繁殖的长距离迁徙者[13-17]。
