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.

美拉黑按蚊（Anopheles melas）是一种栖息于半咸水环境的按蚊，分布于西非沿海区域，在当地为主要的传疟媒介（malaria vector）。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）开展了美拉黑按蚊的测序分析。基于重复序列数目与侧翼序列（flanking regions）筛选出合格的候选位点后，研究人员对来自赤道几内亚的2个自然种群进行了扩增检测。最终仅15个位点可被认定为适用于美拉黑按蚊种群的多态性标记（polymorphic markers）。研究人员随后在覆盖更广地理范围的4个种群中对这些位点进行了筛查，结果显示：杂合度估计值（heterozygosity estimates）介于0.18至0.79之间，每个位点的平均等位基因数为2.5至15个，最终得到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姊妹物种（sibling species）中的应用价值，研究人员使用原本针对冈比亚按蚊开发的特异性标记对美拉黑按蚊的5个位点进行了扩增，结果在1个原冈比亚按蚊标记中发现了无效等位基因（null alleles）。本文讨论了在近缘物种间跨类使用微卫星位点的潜在缺陷，并得出结论：除该操作伴随的无效等位基因问题外，即便将微卫星标记应用于姊妹物种，许多位点也可能仅能发挥极为有限的多态性标记效用。