Divergent mechanisms of reduced growth performance in Betula ermanii saplings from high-altitude and low-latitude range

Plant species are distributed in their preferred climatic zones, and plants growing at the edge of their natural distribution range often exhibit poor growth when relocated to a different environment. This phenomenon has been attributed to two factors: 1) the environment at the edge of the distribution is extreme for the species, causing them to lose their adaptive ability in a different environment, and 2) the small size and isolation of the population make them susceptible to inbreeding and genetic drift. However, the specific mechanisms by which these two factors cause reduced growth have not been well understood.