Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.
Department of Biological Sciences, University of Adelaide, Adelaide, SA, 5005, Australia.
Sci Rep. 2019 Mar 18;9(1):4730. doi: 10.1038/s41598-019-40865-3.
Although hybridization between non-sibling species rarely results in viable or fertile offspring, it occasionally produces self-perpetuating or sexually-parasitic lineages in which ancestral genomes are inherited clonally and thus may persist as 'ghost species' after ancestor extinction. Ghost species have been detected in animals and plants, for polyploid and diploid organisms, and across clonal, semi-clonal, and even sexual reproductive modes. Here we use a detailed investigation of the evolutionary and taxonomic status of a newly-discovered, putative ghost lineage (HX) in the fish genus Hypseleotris to provide perspectives on several important issues not previously explored by other studies on ghost species, but relevant to ongoing discussions about their detection, conservation, and artificial re-creation. Our comprehensive genetic (allozymes, mtDNA) and genomic (SNPs) datasets successfully identified a threatened sexual population of HX in one tiny portion of the extensive distribution displayed by two hemi-clonal HX-containing lineages. We also discuss what confidence should be placed on any assertion that an ancestral species is actually extinct, and how to assess whether any putative sexual ancestor represents a pure remnant, as shown here, or a naturally-occurring resurrection via the crossing of compatible clones or hemi-clones.
尽管非亲缘物种之间的杂交很少产生可育或有活力的后代，但它偶尔会产生自我延续或性寄生的谱系，其中祖先基因组以克隆方式遗传，因此在祖先灭绝后可能作为“幽灵物种”而存在。幽灵物种已在动物和植物中被发现，包括多倍体和二倍体生物，以及克隆、半克隆甚至有性繁殖模式。在这里，我们使用对新发现的鱼类 Hypseleotris 属中假定的幽灵谱系（HX）的详细进化和分类地位的调查，为其他关于幽灵物种的研究尚未探讨但与关于它们的检测、保护和人工再现的正在进行的讨论相关的几个重要问题提供了视角。我们全面的遗传（等位酶、mtDNA）和基因组（SNP）数据集成功地在两个包含 HX 的半克隆谱系所展示的广泛分布的一小部分中识别出了 HX 的受威胁有性种群。我们还讨论了对于任何声称某个祖先物种实际上已经灭绝的说法应该有多大的信心，以及如何评估任何假定的有性祖先是否代表了一个纯粹的残余，就像这里所示的那样，或者是通过相容的克隆或半克隆的杂交自然复活。
