The black grouse Lyrurus tetrix and the capercaillie Tetrao urogallus are known to produce hybrids in wild populations. In general, these hybrids are regarded as infertile; however, conclusive evidence that F1-hybrids are infertile and unable to backcross in the wild are lacking. Using a molecular approach, we examined the ancestry of a bird assumed to be a male hybrid based on phenotypic characters. The specimen was legally shot during the hunting season in northern Norway in an area where the black grouse is common and the capercaillie is relatively rare. Analysis of the maternally inherited mitochondrial DNA revealed that the mother of the specimen was of capercaillie origin, while a diagnostic sex-chromosome (Z) linked microsatellite marker showed that the father had a black grouse allele. Diagnostic autosomal microsatellite markers revealed that the specimen was a backcross and not a first-generation hybrid. As galliform birds follow Haldane’s rule, i.e., that hybrid sterility is common in the heterogametic sex (female in birds), the hybrid parent of the backcross was, thus, likely a male. Our findings provide molecular evidence that capercaillie × black grouse F1-hybrid males can be fertile and successfully mate and backcross in a wild population.

中文翻译：

---

用分子标记揭示了野生Capercaillie×黑松鸡杂种的回交

黑松鸡Lyrurus tetrix和Capercaillie Tetrao urogallus已知在野生种群中会产生杂种。通常，这些杂种被认为是不育的。但是，缺乏F1杂种不育并且无法在野外回交的确凿证据。使用分子方法，我们根据表型特征检查了假定为雄性杂种的鸟的祖先。该标本是在挪威北部的狩猎季节合法拍摄的，该地区黑松鸡很常见，而卡德卡利是相对罕见的地区。对母体遗传的线粒体DNA的分析表明，标本的母亲来自卡佩卡利，而诊断性染色体（Z）连锁的微卫星标记表明，父亲具有黑松鸡等位基因。诊断性常染色体微卫星标记显示该标本是回交的，而不是第一代杂种。由于鸡形鸟遵循霍尔丹的规则，即杂种不育在异性配偶中很常见（鸟类中为雌性），因此回交的杂种亲本很可能是雄性。我们的发现提供了分子证据，表明卡普卡利×黑松鸡F1杂种雄性可以繁殖，并且可以在野生种群中成功交配和回交。