Ma W, Lambert D
Department of Ecology, Massey University, Palmerston North, New Zealand.
Electrophoresis. 1997 Aug;18(9):1682-7. doi: 10.1002/elps.1150180936.
We have used multilocus minisatellite DNA profiling to assess genetic variation in the endangered and highly inbred black robins and the closely related tomtits. These species are restricted to wild populations on the Chatham Islands, off the east coast of New Zealand. DNA profiles revealed a remarkable degree of genetic similarity among black robins, as well as among the tomtits sampled, although the typical profiles of these two species were clearly distinct. The parentage of two putative hybrid chicks and one putative hybrid adult was established for a 'black robin' adult male and an adult tomtit female which were found nesting together. The 'black robin' male, despite being morphologically a typical black robin, was found to possess a number of minisatellite-containing restriction fragments not recorded from the black robin population (n = 103). These fragments were however detected in tomtits. Consequently, this bird appeared to be an F1 hybrid and his three offspring were F2 hybrids. Mitochondrial DNA sequencing of members of this family showed that the 'black robin' male had cytochrome b and 16S of black robin, rather than tomtit, haplotypes. This indicates that the black robin adult male hybrid was the result of a black robin female mating with a tomtit male. These findings are particularly important since tomtits had been used as cross-foster parents for black robins, as part of an earlier conservation recovery program. The existence of any hybrids thus detected would have important implications for cross-fostering programs generally, since may such programs are now being implemented in conservation programs worldwide.
我们利用多位点微卫星DNA图谱来评估濒危且高度近亲繁殖的黑知更鸟以及与之亲缘关系密切的汤氏吸蜜鸟的遗传变异。这些物种仅分布于新西兰东海岸外查塔姆群岛的野生种群中。DNA图谱显示，黑知更鸟之间以及所采样的汤氏吸蜜鸟之间存在显著程度的遗传相似性，尽管这两个物种的典型图谱明显不同。对于一只在一起筑巢的“黑知更鸟”成年雄鸟和一只成年汤氏吸蜜鸟雌鸟所产下的两只疑似杂交雏鸟和一只疑似杂交成年鸟，确定了其亲本关系。尽管这只“黑知更鸟”雄鸟在形态上是典型的黑知更鸟，但发现它拥有一些黑知更鸟种群（n = 103）中未记录的含微卫星的限制性片段。然而，这些片段在汤氏吸蜜鸟中被检测到。因此，这只鸟似乎是一只F1杂种，它的三只后代是F2杂种。对这个家族成员的线粒体DNA测序表明，这只“黑知更鸟”雄鸟具有黑知更鸟的细胞色素b和16S单倍型，而不是汤氏吸蜜鸟的。这表明这只黑知更鸟成年雄杂种是一只黑知更鸟雌鸟与一只汤氏吸蜜鸟雄鸟交配的结果。这些发现尤为重要，因为作为早期保护恢复计划的一部分，汤氏吸蜜鸟曾被用作黑知更鸟的交叉寄养亲本。因此检测到的任何杂种的存在通常都会对交叉寄养计划产生重要影响，因为现在全球范围内的保护计划中正在实施许多这样的计划。
