Data from: Reef fish hybridisation: lessons learnt from butterflyfishes (genus Chaetodon)

Natural hybridisation is widespread among coral reef fishes. However, the ecological promoters and evolutionary consequences of reef fish hybridisation have not been thoroughly evaluated. Butterflyfishes form a high number of hybrids and represent an appropriate group to investigate hybridisation in reef fishes. This study provides a rare test of terrestrially-derived hybridisation theory in the marine environment by examining hybridisation between Chaetodon trifasciatus and Chaetodon lunulatus at Christmas Island. Overlapping spatial and dietary ecologies enable heterospecific encounters. Non-assortative mating and local rarity of both parent species appear to permit heterospecific breeding pair formation. Microsatellite loci and mtDNA confirmed the status of hybrids, which displayed the lowest genetic diversity in the sample and used a reduced suite of resources, suggesting decreased adaptability. Maternal contribution to hybridisation was unidirectional, and no introgression was detected, suggesting limited, localised evolutionary consequences of hybridisation. Comparisons to other reef fish hybridisation studies revealed that different evolutionary consequences emerge, despite being promoted by similar factors, possibly due to the magnitude of genetic distance between hybridising species. This study highlights the need for further enquiry aimed at evaluating the importance and long-term consequences of reef fish hybridisation.自然杂交（natural hybridisation）在珊瑚礁鱼类类群中广泛分布。然而，珊瑚礁鱼类杂交的生态驱动因子与进化后果尚未得到充分评估。蝴蝶鱼类（butterflyfishes）产生了数量众多的杂交个体，是探究礁栖鱼类杂交现象的适宜研究类群。本研究以圣诞岛（Christmas Island）的三带蝴蝶鱼（*Chaetodon trifasciatus*）与新月蝴蝶鱼（*Chaetodon lunulatus*）为研究对象，在海洋环境中对源自陆地的杂交理论开展了罕见的实证检验。二者在空间与食性生态上的重叠，为异种个体间的相遇提供了可能。非选型交配（non-assortative mating）以及两个亲本物种的局部稀有性，似乎促成了异种繁殖配对的形成。微卫星位点（microsatellite loci）与线粒体DNA（mtDNA）分析证实了杂交个体的身份，相较于样本中的其他个体，杂交个体的遗传多样性最低，且资源利用谱显著缩减，这提示其适应性有所降低。杂交过程中的母系贡献呈单向性，且未检测到基因渐渗（introgression）现象，这表明杂交带来的进化后果局限于局部区域且程度有限。与其他珊瑚礁鱼类杂交相关研究的对比结果显示，尽管受相似的驱动因子影响，不同研究中的杂交进化后果存在差异，这可能源于杂交物种间的遗传距离大小差异。本研究强调，亟需开展更多相关探究工作，以系统评估珊瑚礁鱼类杂交的生态学意义与长期进化后果。