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...携带新型或外源基因元件的林木，有望在林业领域为生物能源生产、植物修复（phytoremediation）、碳封存（carbon sequestration）等多种应用场景支撑生物经济发展，但在大规模人工林可持续释放具备新颖性状的林木时，需量化其对本土树木种群构成的风险。近一个世纪以来，经人工杂交培育的外来杂交杨树被广泛栽植于加拿大东部地区，用作观赏植物或防风林；这些外来树种为我们在自然环境中探究外来杨树性状的适合度，进而评估外来基因逃逸、定植并扩散至本土基因库的风险提供了替代研究模型。本研究于加拿大东部（魁北克省魁北克市）的一处天然更新林分（naturally regenerated stand）中，针对本土杨树与外来杨树的合子后适合度性状（postzygotic fitness traits）开展了评估。供试材料包括纯本土杨树（香脂杨 *P. balsamifera* 与三角杨 *P. deltoides spp. deltoides*）、本土杂交杨（三角杨 × 香脂杨 *P. deltoides × P. balsamifera*）以及外来杂交杨（树木……）