Data from: Limited usefulness of microsatellite markers from the malaria vector Anopheles gambiae when applied to the closely related species Anopheles melas

Anopheles melas is a brackish water mosquito found in coastal West Africa where it is a dominant malaria vector locally. In order to facilitate genetic studies of this species, 45 microsatellite loci originally developed for Anopheles gambiae were sequenced in An . melas. Those that were suitable based on repeat number and flanking regions were examined in 2 natural populations from Equatorial Guinea. Only 15 loci were eventually deemed suitable as polymorphic markers in An . melas populations. These loci were screened in 4 populations from a wider geographic range. Heterozygosity estimates ranged from 0.18 to 0.79, and 2.5–15 average alleles were observed per locus, yielding 13 highly polymorphic markers and 2 loci with lower variability. To examine the usefulness of microsatellite markers when applied in a sibling species, the original An . gambiae specific markers were used to amplify 5 loci in An . melas. Null alleles were found for 1 An . gambiae marker. We discuss the pitfalls of using microsatellite loci across closely related species and conclude that in addition to the problem of null alleles associated with this practice, many loci may prove to be of very limited use as polymorphic markers even when used in a sibling species.

暗潮按蚊（Anopheles melas）是一种栖息于西非沿海咸淡水水域的蚊虫，为当地主要的疟疾传播媒介。为推动该物种的遗传学研究，研究人员对原本为冈比亚按蚊（Anopheles gambiae）开发的45个微卫星位点（microsatellite loci），在暗潮按蚊（An. melas）中进行了测序。基于重复序列数量与侧翼区域的适配性筛选出合格位点后，研究人员在来自赤道几内亚的2个自然种群中开展了检测。最终仅15个位点可作为暗潮按蚊（An. melas）种群的多态性分子标记。随后，研究人员在地理覆盖范围更广的4个种群中对上述位点进行了筛查。结果显示，各位点的杂合度估计值介于0.18至0.79之间，平均等位基因数为2.5至15个，其中包含13个高度多态性标记与2个变异度较低的位点。为验证微卫星标记在近缘物种中的应用效能，研究人员使用原本针对冈比亚按蚊（An. gambiae）开发的特异性标记，对暗潮按蚊（An. melas）中的5个位点进行了扩增，结果发现其中1个标记存在无效等位基因（null alleles）。本文讨论了跨近缘物种使用微卫星位点的潜在应用陷阱，并得出结论：除该方法伴随的无效等位基因问题外，即便在近缘物种中应用，多数位点也可能仅具备极为有限的多态性标记应用价值。