Department of Ecology, Swedish University of Agricultural Sciences Box 7044, 75007, Uppsala, Sweden ; Institute of Forest Ecology, Slovak Academy of Sciences Ľ. Štúra 2, 96053, Zvolen, Slovakia.
Department of Ecology, Swedish University of Agricultural Sciences Box 7044, 75007, Uppsala, Sweden.
Ecol Evol. 2014 Apr;4(7):1117-26. doi: 10.1002/ece3.1005. Epub 2014 Mar 7.
Newly founded isolated populations need to overcome detrimental effects of low genetic diversity. The establishment success of a population may therefore depend on various mechanisms such as assortative mating, purging of deleterious alleles, creation of new mutations and/or repeated inflow of new genotypes to reduce the effects of inbreeding and further loss of genetic variation. We compared the level of genetic variation in introduced populations of an insect species (Metrioptera roeselii) far beyond its natural distribution with levels found in their respective founder populations and coupled the data with timing since establishment. This allowed us to analyze if the introduced populations showed signs of temporal changes in genetic variation and have made it possible to evaluate underlying mechanisms. For this, we used neutral genetic markers, seven microsatellite loci and a 676-bp-long sequence of the mtDNA COI gene. All tested indices (allelic richness, unbiased expected heterozygosity, effective size, haplotype diversity, and nucleotide diversity) except inbreeding coefficient had significantly higher values in populations within the founding populations inside the continuous area of the species distribution compared with the introduced populations. A logarithmic model showed a significant correlation of both allelic richness and unbiased expected heterozygosity with age of the isolated populations. Considering the species' inferred colonization history and likely introduction pathways, we suggest that multiple introductions are the main mechanism behind the temporal pattern observed. However, we argue that influences of assortative mating, directional selection, and effects of an exceptional high intrapopulation mutation rate may have impacts. The ability to regain genetic diversity at this level may be one of the main reasons why M. roeselii successfully continue to colonize northern Europe.
新成立的隔离种群需要克服遗传多样性低的不利影响。因此，种群的建立成功可能取决于各种机制，如交配选择、有害等位基因的清除、新突变的产生和/或新基因型的重复流入，以减少近交和进一步遗传变异损失的影响。我们比较了一种昆虫物种（Metrioptera roeselii）引入种群的遗传变异水平，这些种群远远超出了其自然分布范围，并将这些数据与建立时间结合起来。这使我们能够分析引入种群是否表现出遗传变异的时间变化迹象，并评估潜在的机制。为此，我们使用了中性遗传标记、七个微卫星位点和 mtDNA COI 基因的 676bp 长序列。除近交系数外，所有测试的指标（等位基因丰富度、无偏期望杂合度、有效大小、单倍型多样性和核苷酸多样性）在连续分布区的创始种群内的种群中均显著高于引入种群。对数模型显示，等位基因丰富度和无偏期望杂合度与隔离种群的年龄呈显著相关。考虑到物种的推断殖民历史和可能的引入途径，我们认为多次引入是观察到的时间模式的主要机制。然而，我们认为交配选择、定向选择和异常高的种群内突变率的影响可能会产生影响。在这种水平上恢复遗传多样性的能力可能是 M. roeselii 成功继续在北欧殖民的主要原因之一。
