Molecular patterns of adaptive variation in spruces

北方云杉是自然分布最广的生物体之一。它们一般具有遗传多样性高、种群规模大的特点。随着冰川的消退，这些物种最近才重新整合了它们的活动范围。相比之下，亚热带云杉的分布范围要小得多，它们的出现仅限于高海拔地区。它们的遗传多样性普遍减少，随着全新世变暖，它们的生存范围不断缩小。然而，目前尚不清楚这种差异是否会反映在适应性遗传变异的水平上，因为类似的适应可能是为了在南方或北纬较高海拔的较冷气候下生存而进化出来的。我们的研究计划的目标是在分子水平上破译长寿命的未驯化生物(如针叶树)的适应结构。一个主要目标是识别含有适应性遗传变异的基因，并评估适应性变异模式在云杉之间是如何相关的。未驯化植物种群遗传学的一个主要障碍是普遍缺乏与适应或其他重要数量性状相关的分子遗传标记。最近，我们已经证明，通过对涉及数百个基因的基因组进行离群识别扫描，可以识别可能涉及适应性遗传变异的基因多态(SNPs)。基于这些结果，将研究自适应离群值SNPs在范围内的变化模式。在云杉基因家族中，将进一步筛选具有最近重复的选择特征。一组跨越基因组的同源基因将在不同的云杉物种中进行测序，以确定它们的分子适应系数。这项研究计划应该会产生新的遗传标记，允许监测云杉遗传景观中的适应性基因变异。这些标记将允许估计不同物种之间适应基因含量的重叠，并在基因水平上更好地理解适应的动态。它们将允许更好地监测适应性遗传资源，这正成为一项紧迫的任务，特别是对濒危亚热带物种而言。

Boreal spruces are among living organisms with the largest natural distributions. They are generally characterized by high genetic diversity and large population size. These species have only recently re-integrated their ranges following the retreat of glaciers. In contrast, subtropical spruces have much smaller distribution ranges and their occurrence is limited to areas of high altitude. They generally harbor reduced genetic diversity and have suffered an on-going range contraction with the Holocene warming. However, it is not clear if such differences would be reflected at the level of adaptive genetic variation, given that similar adaptations might have evolved to survive colder climates at higher elevations in the south or at northern latitudes. The goal of our research program is to decipher the architecture of adaptation at the molecular level in long-lived undomesticated organisms such as conifers. One major aim is to identify genes harboring adaptive genetic variation and evaluate how patterns of adaptive variation are correlated among spruces. A main obstacle in population genetics of undomesticated plant species is the general lack of molecular genetic markers related to adaptation or other important quantitative traits. Recently, we have shown that it was possible to identify gene polymorphisms (SNPs) potentially involved in adaptive genetic variation, using outlier identification scans of the genome implicating hundreds of genes. Based on these results, range-wide patterns of variation for adaptive outlier SNPs will be investigated. Selection signatures will further be screened in spruce gene families with recent duplicates. A homeologous set of genes spanning the genome will be sequenced in different spruce species to determine their coefficient of molecular adaptation. This research program should result in new genetic markers allowing to monitor adaptive gene variation across spruce genetic landscapes. These markers will allow to estimate the overlap in adaptive gene content among different species and better understand the dynamics of adaptation at the gene level. They will allow to better monitor adaptive genetic resources, which is becoming an urgent task, particularly for endangered subtropical species.