Data from: Hierarchical behaviour, habitat use and species size differences shape evolutionary outcomes of hybridization in a coral reef fish.

Hybridization is an important evolutionary process, with ecological and behavioural factors influencing gene exchange between hybrids and parent species. Patterns of hybridization in anemonefishes may result from living in highly specialized habitats and breeding status regulated by size-based hierarchal social groups. Here morphological, ecological and genetic analyses in Kimbe Bay, Papua New Guinea examine the hybrid status of Amphiprion leucokranos, a nominal species and presumed hybrid between Amphiprion sandaracinos and Amphiprion chrysopterus. We test the hypothesis that habitat use and relative size differences of the parent species and hybrids determine patterns of gene exchange. There is strong evidence that A. leucokranos is a hybrid of smaller A. sandaracinos and larger A. chrysopterus, where A. chrysopterus is exclusively the mother to each hybrid, based on mtDNA cytochrome b and multiple nDNA microsatellite loci. Overlap in habitat, depth and host anemone use was found, with hybrids intermediate to parents and co-habitation in over 25% of anemones sampled. Hybrids, intermediate in body size, colour and pattern, were classified 55% of the time as morphologically first generation hybrids relative to parents, whereas 45% of hybrids were more A. sandaracinos-like, suggesting back-crossing. Unidirectional introgression of A. chrysopterus mtDNA into A. sandaracinos via hybrid backcrosses was found, with larger female hybrids and small male A. sandaracinos mating. Potential nDNA introgression was also evident through distinct intermediate hybrid genotypes penetrating both parent species. Findings support the hypothesis that anemonefish hierarchical behaviour, habitat use, and species-specific size differences determine how hybrids form and the evolutionary consequences of hybridization.杂交是一类重要的演化过程，生态与行为因素会影响杂交个体与亲本物种间的基因交流。海葵鱼（anemonefishes）的杂交模式，可能源于其栖息于高度特化的生境，以及繁殖地位由基于体型的等级社会群体调控。本研究于巴布亚新几内亚金贝湾开展形态学、生态学与遗传学分析，旨在明确白顶双锯鱼（Amphiprion leucokranos）的杂交属性——该物种曾被列为名义物种，且被推测为白带双锯鱼（Amphiprion sandaracinos）与橙鳍双锯鱼（Amphiprion chrysopterus）的杂交后代。本研究验证了如下假说：亲本物种与杂交个体的生境利用偏好及体型相对差异，决定了基因交流的模式。基于线粒体DNA（mtDNA）细胞色素b（cytochrome b）基因以及多个核DNA（nDNA）微卫星位点（microsatellite loci）的分析结果，有充分证据表明，白顶双锯鱼是体型较小的白带双锯鱼与体型较大的橙鳍双锯鱼的杂交后代，且所有杂交个体的母本均为橙鳍双锯鱼。研究发现，杂交个体与亲本在生境、栖息深度及宿主海葵选择上存在重叠：杂交个体的相关性状介于两个亲本之间，且在超过25%的采样海葵中，杂交个体与亲本存在共栖现象。杂交个体的体型、体色与花纹均介于两个亲本之间，其中55%的个体经形态学鉴定为F1代杂交个体（first generation hybrids），剩余45%的个体更接近白带双锯鱼，提示存在回交（back-crossing）现象。研究发现，通过杂交回交，橙鳍双锯鱼的线粒体DNA发生了单向渐渗（introgression）至白带双锯鱼的现象，其交配组合为体型较大的雌性杂交个体与体型较小的雄性白带双锯鱼。此外，通过在两个亲本物种中均检测到独特的中间型杂交基因型，可发现核DNA存在潜在的渐渗现象。本研究结果验证了如下假说：海葵鱼的等级社会行为、生境利用偏好以及物种特有的体型差异，决定了杂交的形成方式以及杂交带来的演化后果。