Simon J C, Baumann S, Sunnucks P, Hebert P D, Pierre J S, Le Gallic J F, Dedryver C A
Laboratoire de Zoologie, INRA, Le Rheu, France.
Mol Ecol. 1999 Apr;8(4):531-45. doi: 10.1046/j.1365-294x.1999.00583.x.
As French populations of the aphid Sitobion avenae exhibit a range of reproductive modes, this species provides a good opportunity for studying the evolution of breeding system variation. The present analysis combined ecological and genetic investigations into the spatial distribution of variation in reproductive mode. Reproductive mode was characterized in 277 lineages of S. avenae from France, and these aphids were scored for five microsatellite loci. The analyses revealed strong geographical partitioning of breeding systems, with obligate asexuals mostly restricted to the south of France, while lineages producing sexual forms were more common in the north. Contrary to what might be anticipated for organisms with frequent parthenogenesis, there was substantial genic and genotypic diversity, even in the obligately asexual lineages. More than 120 different genotypes were detected among the 277 aphid lineages, with an average of 5.9 alleles per locus (range four to 16) and heterozygosity of 56.7%. As with previous studies of allozyme variation in aphids, most loci showed heterozygote deficits, and disequilibrium was common among allelic variants at different loci, even after removal of replicate copies of genotypes that might have been derived through clonal reproduction. Our results suggest that selection is important in structuring reproductive systems and genetic variation in French S. avenae. Canonical correspondence analysis was employed to examine the associations between genotypic and phenotypic variables, enabling the identification of alleles correlated with life-history traits.
由于法国麦长管蚜种群呈现出一系列繁殖模式，该物种为研究繁殖系统变异的进化提供了一个很好的机会。本分析将生态和遗传调查结合起来，研究繁殖模式变异的空间分布。对来自法国的277个麦长管蚜谱系的繁殖模式进行了特征描述，并对这些蚜虫的五个微卫星位点进行了评分。分析揭示了繁殖系统的强烈地理分区，专性孤雌生殖型主要局限于法国南部，而产生有性型的谱系在北部更为常见。与预期的频繁孤雌生殖生物不同，即使在专性孤雌生殖谱系中也存在大量的基因和基因型多样性。在277个蚜虫谱系中检测到120多种不同的基因型，每个位点平均有5.9个等位基因（范围为4至16个），杂合度为56.7%。与之前对蚜虫等位酶变异的研究一样，大多数位点显示杂合子缺失，不同位点的等位基因变体之间不平衡很常见，即使在去除可能通过克隆繁殖产生的重复基因型副本之后也是如此。我们的结果表明，选择在构建法国麦长管蚜的繁殖系统和遗传变异中很重要。采用典范对应分析来检验基因型和表型变量之间的关联，从而能够识别与生活史特征相关的等位基因。
