Biodiversity Research Centre, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
PLoS One. 2010 Nov 3;5(11):e13810. doi: 10.1371/journal.pone.0013810.
Past and current range or spatial expansions have important consequences on population genetic structure. Habitat-use expansion, i.e. changing habitat associations, may also influence genetic population parameters, but has been less studied. Here we examined the genetic population structure of a Palaeartic woodland butterfly Pararge aegeria (Nymphalidae) which has recently colonized agricultural landscapes in NW-Europe. Butterflies from woodland and agricultural landscapes differ in several phenotypic traits (including morphology, behavior and life history). We investigated whether phenotypic divergence is accompanied by genetic divergence between populations of different landscapes along a 700 km latitudinal gradient.
METHODOLOGY/PRINCIPAL FINDINGS: Populations (23) along the latitudinal gradient in both landscape types were analyzed using microsatellite and allozyme markers. A general decrease in genetic diversity with latitude was detected, likely due to post-glacial colonization effects. Contrary to expectations, agricultural landscapes were not less diverse and no significant bottlenecks were detected. Nonetheless, a genetic signature of recent colonization is reflected in the absence of clinal genetic differentiation within the agricultural landscape, significantly lower gene flow between agricultural populations (3.494) than between woodland populations (4.183), and significantly higher genetic differentiation between agricultural (0.050) than woodland (0.034) pairwise comparisons, likely due to multiple founder events. Globally, the genetic data suggest multiple long distance dispersal/colonization events and subsequent high intra- and inter-landscape gene flow in this species. Phosphoglucomutase deviated from other enzymes and microsatellite markers, and hence may be under selection along the latitudinal gradient but not between landscape types. Phenotypic divergence was greater than genetic divergence, indicating directional selection on some flight morphology traits.
MAIN CONCLUSIONS/SIGNIFICANCE: Clinal differentiation characterizes the population structure within the original woodland habitat. Genetic signatures of recent habitat expansion remain, notwithstanding high gene flow. After differentiation through drift was excluded, both latitude and landscape were significant factors inducing spatially variable phenotypic variation.
过去和当前的范围或空间扩张对人口遗传结构有重要影响。栖息地利用的扩张，即改变栖息地的联系，也可能影响遗传种群参数，但研究较少。本文研究了最近在北欧-欧洲农业景观中定居的鳞翅目林地蝴蝶 Pararge aegeria 的遗传种群结构。林地和农业景观中的蝴蝶在几个表型特征上存在差异（包括形态、行为和生活史）。我们调查了在 700 公里的纬度梯度上，不同景观类型的种群之间的表型分歧是否伴随着遗传分歧。
方法/主要发现：利用微卫星和同工酶标记物分析了该纬度梯度上两种景观类型的 23 个种群。检测到遗传多样性随纬度的普遍下降，这可能是由于后冰河时代的殖民化效应。与预期相反，农业景观的多样性并不低，也没有检测到明显的瓶颈。尽管如此，在农业景观中不存在渐进的遗传分化，农业种群之间的基因流（3.494）明显低于林地种群之间的基因流（4.183），以及农业（0.050）与林地（0.034）之间的遗传分化显著较高，这表明最近的殖民化有遗传特征，这可能是由于多次奠基事件。总的来说，遗传数据表明该物种存在多次长距离扩散/殖民事件，随后在该物种内部和景观之间有较高的基因流动。磷酸葡萄糖变位酶与其他酶和微卫星标记物不同，因此可能沿着纬度梯度受到选择，但不在景观类型之间受到选择。表型分歧大于遗传分歧，表明对一些飞行形态特征存在定向选择。
主要结论/意义：在原始林地栖息地内，种群结构具有渐增分化特征。尽管基因流动较高，但仍存在最近栖息地扩张的遗传特征。在排除分化通过漂移后，纬度和景观都是诱导空间上可变表型变异的重要因素。
