Jump Alistair S, Woodward F Ian, Burke Terry
Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
New Phytol. 2003 Nov;160(2):359-370. doi: 10.1046/j.1469-8137.2003.00874.x.
• Genetic variation was assessed across the UK geographical range of Cirsium acaule and Cirsium heterophyllum. A decline in genetic diversity and increase in population divergence approaching the range edge of these species was predicted based on parallel declines in population density and seed production reported seperately. Patterns were compared with UK populations of the widespread Cirsium arvense. • Populations were sampled along a latitudinal transect in the UK and genetic variation assessed using microsatellite markers. • Cirsium acaule shows strong isolation by distance, a significant decline in diversity and an increase in divergence among range-edge populations. Geographical structure is also evident in C. arvense, whereas no such patterns are seen in C. heterophyllum. • There is a major disparity between patterns of genetic variation in C. acaule and C. heterophyllum despite very similar patterns in seed production and population isolation in these species. This suggests it may be misleading to make assumptions about the geographical structure of genetic variation within species based solely on the present-day reproduction and distribution of populations.
• 对全英国范围内的无茎蓟和异叶蓟的遗传变异进行了评估。根据之前分别报道的种群密度和种子产量的平行下降情况，预计在这些物种的分布范围边缘，遗传多样性会下降，种群分化会增加。将这些模式与广泛分布的田蓟在英国的种群进行了比较。
• 在英国沿纬度梯度对种群进行采样，并使用微卫星标记评估遗传变异。
• 无茎蓟表现出强烈的距离隔离、多样性显著下降以及分布范围边缘种群之间的分化增加。田蓟也存在明显的地理结构，而异叶蓟则没有这种模式。
• 尽管无茎蓟和异叶蓟在种子产量和种群隔离方面的模式非常相似，但它们在遗传变异模式上存在重大差异。这表明仅根据当前种群的繁殖和分布情况来推断物种内遗传变异的地理结构可能会产生误导。
