Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J Evol Biol. 2011 Feb;24(2):381-90. doi: 10.1111/j.1420-9101.2010.02174.x. Epub 2010 Nov 19.
Variation in morphological traits along latitudinal gradients often manifests as size clines. In insects, both positive and negative correlations are seen, and the mechanism behind the response is unclear. We studied variation in seven morphological traits of Roesel's bush cricket, Metrioptera roeselii, sampled from seven latitude-matched-pair populations that were either geographically isolated from or connected to the species continuous distribution range. The aim was to examine whether morphological traits differed between isolated and continuous populations, and whether latitudinal variation was apparent. The data were used to indicate whether variation in trait means originates from plastic responses to the environment or genetic adaptation to local conditions. To evaluate the influence of gene flow on trait means, we analysed the genetic variation in seven microsatellites. Data showed that individuals from isolated populations display a positive relationship between latitude and body size, whereas individuals from continuous populations show little or no such relationship. The combined morphological and genetic data suggest that the isolated populations have adapted to local optima, while gene flow between continuous populations appears to counteract this process.
纬度梯度上形态特征的变化通常表现为体型梯度。在昆虫中，既有正相关也有负相关，其背后的响应机制尚不清楚。我们研究了来自 7 个地理隔离或与物种连续分布区相连的配对种群的罗泽氏灌木蟋蟀（Metrioptera roeselii）的 7 个形态特征的变化。目的是检验形态特征是否在隔离和连续种群之间存在差异，以及是否存在纬度变化。这些数据用于指示特征均值的变化是源于对环境的可塑性响应还是对当地条件的遗传适应。为了评估基因流对特征均值的影响，我们分析了 7 个微卫星的遗传变异。数据表明，来自隔离种群的个体的体型与纬度之间呈正相关关系，而来自连续种群的个体则很少或没有这种关系。综合形态和遗传数据表明，隔离种群已经适应了局部最优，而连续种群之间的基因流似乎抵消了这一过程。
