Data from: Fitness dynamics within a poplar hybrid zone: II. Impact of exotic sex on native poplars in an urban jungle.

Trees bearing novel or exotic gene components are poised to contribute to the bioeconomy for a variety of purposes such as bioenergy production, phytoremediation, and carbon sequestration within the forestry sector, but sustainable release of trees with novel traits in large-scale plantations requires the quantification of risks posed to native tree populations. Over the last century, exotic hybrid poplars produced through artificial crosses were planted throughout eastern Canada as ornamentals or windbreaks and these exotics provide a proxy by which to examine the fitness of exotic poplar traits within the natural environment to assess risk of exotic gene escape, establishment, and spread into native gene pools. We assessed postzygotic fitness traits of native and exotic poplars within a naturally regenerated stand in eastern Canada (Quebec City, QC). Pure natives (P. balsamifera and P. deltoides spp. deltoides), native hybrids (P. deltoides × P. balsamifera), and exotic hybrids (trees bearing Populus nigra and P. maximowiczii genetic components) were screened for reproductive biomass, yield, seed germination, and fungal disease susceptibility. Exotic hybrids expressed fitness traits intermediate to pure species and were not significantly different from native hybrids. They formed fully viable seed and backcrossed predominantly with P. balsamifera. These data show that exotic hybrids were not unfit and were capable of establishing and competing within the native stand. Future research will seek to examine the impact of exotic gene regions on associated biotic communities to fully quantify the risk exotic poplars pose to native poplar forests.携带新型或外源基因组分的林木，有望在林业领域为生物能源生产、植物修复（phytoremediation）、碳封存（carbon sequestration）等多种用途助力生物经济（bioeconomy）发展，但在大规模人工林可持续释放具有新颖性状的林木，需量化其对本土林木种群构成的风险。过去一个世纪以来，通过人工杂交培育的外来杂交杨已在加拿大东部广泛种植，用作观赏植物或防风林；这些外来树种为探究自然环境中外来杨性状的适合度提供了研究载体（proxy），以此评估外源基因逃逸、定植并扩散至本土基因库的风险。本研究针对加拿大东部（魁北克市，魁北克省）一处天然更新林分（naturally regenerated stand）中的本土与外来杨树种，开展了合子后适合度性状（postzygotic fitness traits）评估。研究对纯本土树种（香脂杨（P. balsamifera）与三角叶杨原亚种（P. deltoides spp. deltoides））、本土杂交种（三角叶杨×香脂杨（P. deltoides × P. balsamifera））以及外来杂交种（携带欧洲黑杨（P. nigra）与马氏杨（P. maximowiczii）遗传组分的林木）的生殖生物量、产量、种子萌发率与真菌病害易感性进行了筛选检测。结果显示，外来杂交种的适合度性状介于两个纯系物种之间，且与本土杂交种无显著统计学差异；其可产生完全可育的种子，并主要以回交（backcross）方式与香脂杨发生杂交。上述数据表明，外来杂交种并非存在生存劣势，且能够在本土林分中成功定植并参与竞争。未来研究将聚焦于探究外源基因区域对相关生物群落的影响，以全面量化外来杨对本土杨树林地构成的风险。