Introgression from Populus balsamifera underlies adaptively significant variation and range boundaries in P. trichocarpa

Corresponding author: Quentin C. B. Cronk

Introgression (基因渗入) can be an important source of adaptive phenotypes, although conversely (相反地) it can have deleterious effects (有害影响). Evidence for adaptive introgression is accumulating but information on the genetic architecture of introgressed traits lags behind.

Here we determine trait architecture in Populus trichocarpa (毛果杨) under introgression from P. balsamifera (香脂杨) using admixture mapping (混合作图) and phenotypic analyses.

Our results reveal that admixture is a key driver of clinal (种群的) adaptation and suggest that the northern range extension of P. trichocarpa depends, at least in part, on introgression from P. balsamifera. However, admixture with P. balsamifera can lead to potentially maladaptive (不适应的) early phenology (生物气候学), and a reduction in growth and disease resistance in P. trichocarpa. Strikingly (引人侧目地), an introgressed chromosome 9 haplotype (单倍型) block from P. balsamifera restores (恢复) the late phenology and high growth parental phenotype in admixed P. trichocarpa. This epistatic (上位性的) restorer block may be strongly advantageous (有利的) in maximizing carbon assimilation (碳同化) and disease resistance in the southernmost populations where admixture has been detected. We also confirm a previously demonstrated case of adaptive introgression in chromosome 15 and show that introgression generates a transgressive chlorophyll-content phenotype.

We provide strong support that introgression provides a reservoir (蓄积) of genetic variation associated with adaptive characters that allows improved survival in new environments.

本文利用混合作图及表型分析研究了杨树种群间基因渗透的影响及作用。（群体遗传学的专业术语太多，不太敢翻译，怕给大家带来不必要的干扰，大家自行理解吧 ^-^ ! ! ! ）

个人简介：1980年，剑桥大学，自然科学学士；1985年，剑桥大学，生物学博士。

doi: 10.1111/nph.14779