De La Torre Amanda R, Wang Tongli, Jaquish Barry, Aitken Sally N
Centre for Forest Conservation Genetics, Department of Forest and Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC, V6T1Z4, Canada.
Department of Ecology and Environmental Sciences, Umeå University, Linneaus väg 6, SE-901 87, Umeå, Sweden.
New Phytol. 2014 Jan;201(2):687-699. doi: 10.1111/nph.12540. Epub 2013 Oct 8.
The nature of selection responsible for the maintenance of the economically and ecologically important Picea glauca × Picea engelmannii hybrid zone was investigated. Genomic, phenotypic and climatic data were used to test assumptions of hybrid zone maintenance and to model future scenarios under climate change. Genome-wide estimates of admixture based on a panel of 86 candidate gene single nucleotide polymorphisms were combined with long-term quantitative data on growth and survival (over 20 yr), as well as one-time assessments of bud burst and bud set phenology, and cold hardiness traits. A total of 15,498 individuals were phenotyped for growth and survival. Our results suggest that the P. glauca × P. engelmannii hybrid zone is maintained by local adaptation to growing season length and snowpack (exogenous selection). Hybrids appeared to be fitter than pure species in intermediate environments, which fits expectations of the bounded hybrid superiority model of hybrid zone maintenance. Adaptive introgression from parental species has probably contributed to increased hybrid fitness in intermediate habitats. While P. engelmannii ancestry is higher than P. glauca ancestry in hybrid populations, on average, selective breeding in managed hybrid populations is shifting genomic composition towards P. glauca, potentially pre-adapting managed populations to warmer climates.
对负责维持具有经济和生态重要性的白云杉×恩氏云杉杂交带的选择性质进行了研究。利用基因组、表型和气候数据来检验杂交带维持的假设，并对气候变化下的未来情景进行建模。基于一组86个候选基因单核苷酸多态性的全基因组混合估计，与关于生长和存活的长期定量数据（超过20年），以及对芽萌发和芽休眠物候以及抗寒性状的一次性评估相结合。总共对15498个个体进行了生长和存活的表型分析。我们的结果表明，白云杉×恩氏云杉杂交带是通过对生长季节长度和积雪（外源选择）的局部适应来维持的。在中间环境中，杂种似乎比纯种更具适应性，这符合杂交带维持的有界杂种优势模型的预期。亲本物种的适应性渐渗可能有助于提高中间栖息地杂种的适应性。虽然在杂交种群中，恩氏云杉的血统高于白云杉的血统，但平均而言，人工杂交种群中的选择育种正在使基因组组成向白云杉转移，这可能使人工种群对温暖气候具有预先适应性。
