Molecular patterns of adaptive variation in spruces

北方云杉是自然分布最广的生物之一。它们的特点是遗传多样性高，种群规模大。这些物种直到最近才在冰川消退后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，并随着全新世变暖而遭受持续的范围收缩。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，因为类似的适应性可能已经进化到在南方或北方纬度较高的寒冷气候中生存。我们研究计划的目标是在分子水平上破译长寿的未驯化生物体（如针叶树）的适应结构。一个主要的目的是确定具有适应性遗传变异的基因，并评估适应性变异的模式是如何在云杉之间相互关联的。非驯化植物种群遗传学的一个主要障碍是缺乏与适应性或其他重要数量性状相关的分子遗传标记。最近，我们已经表明，它是可能的，以确定基因多态性（SNP）可能涉及适应性遗传变异，使用离群识别扫描的基因组涉及数百个基因。基于这些结果，将研究自适应离群SNP的全范围变异模式。将在最近重复的云杉基因家族中进一步筛选选择标记。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。这项研究计划应该导致新的遗传标记，允许监测适应性基因变异云杉遗传景观。这些标记将允许估计不同物种之间的适应性基因内容的重叠，并更好地了解在基因水平上的适应动态。它们将使人们能够更好地监测适应性遗传资源，这正在成为一项紧迫的任务，特别是对濒危的亚热带物种。

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.