Data from: Bioclimatic, ecological, and phenotypic intermediacy and high genetic admixture in a natural hybrid of octoploid strawberries

PREMISE OF THE STUDY: Hybrid zones provide ‘natural laboratories’ for understanding the processes of selection, reinforcement and speciation. We sought to gain insight into the degree of introgression and the extent of ecological/phenotypic intermediacy in the natural hybrid strawberry, Fragaria × ananassa subsp. cuneifolia. METHODS: We used whole plastome sequencing to identify parental species-specific (Fragaria chiloensis and F. virginiana) chloroplast SNPs, and combined the use of these with nuclear microsatellite markers to genetically characterize the hybrid zone. We assessed the potential role of selection in the observed geographic patterns by bioclimatically characterizing the niche of the hybrid populations and phenotypically characterizing hybrid individuals of known genomic constitution. KEY RESULTS: Significant admixture and little overall maternal bias in chloroplast or nuclear genomes suggest a high degree of inter-fertility among the parental and hybrid species and point to a long history of backcrossing and genetic mixing in the hybrid zone. Even though hybrids were phenotypically intermediate to the parental species there was still a discernible fingerprint of the parental genotype within hybrid individuals. Thus, while the pattern of introgression observed suggests geographic limitations to gene flow, it may be reinforced by selection for specific parental traits in the bioclimatically-intermediate habitat occupied by the hybrid. CONCLUSION: This work uncovered the genetic complexity underlying the hybrid zone of the wild relatives of the cultivated strawberry. It lays the foundation for experimental dissection of the causes of genomic introgression and nuclear-cytoplasmic disassociation, and understanding other parts of the Fragaria evolutionary history.研究背景：杂交带为理解选择、生殖强化与物种形成过程提供了“天然实验室”。本研究旨在解析天然杂交草莓——凤梨草莓楔形亚种（*Fragaria × ananassa* subsp. *cuneifolia*）的遗传渐渗程度，以及其生态与表型中间型的分布范围。 研究方法：本研究通过全质体基因组测序（whole plastome sequencing）鉴定亲本物种（智利草莓*Fragaria chiloensis*与弗吉尼亚草莓*F. virginiana*）的叶绿体单核苷酸多态性（chloroplast SNP），并结合核微卫星标记（nuclear microsatellite marker）对该杂交带进行遗传特征解析。我们通过对杂交种群的生态位进行生物气候学表征，以及对已知基因组组成的杂交个体进行表型特征分析，评估了选择在观测到的地理格局中的潜在作用。 主要结果：叶绿体与核基因组中均存在显著的遗传混合，且整体母系偏向性极低，这表明亲本物种与杂交物种间具有高度的种间可育性，同时也印证了该杂交带长期存在回交与遗传混合的历史。尽管杂交个体的表型介于两个亲本物种之间，但在其基因组中仍可检测到亲本基因型的特征印记。由此可见，尽管观测到的渐渗模式暗示基因流存在地理限制，但杂交种群所处的生物气候中间型生境中针对特定亲本性状的选择作用，可能进一步强化了这一渐渗格局。 研究结论：本研究揭示了栽培草莓野生近缘类群杂交带背后的遗传复杂性。该研究为解析基因组渐渗与核质分离的成因，以及理解草莓属（*Fragaria*）演化历史的其他环节奠定了基础。