Genetic adaptation of tree populations to natural selection

天然云杉种群分布于不同海拔高度的低海拔地区(海拔300米)。至高山地带(1400m ASL.)在北海道中部。对海拔300~1400m的天然居群的针叶形态和生理特性进行了研究，在形态(针叶密度和粗度)和生理性状(叶绿素a+b/氮的比值)上沿海拔方向均有线条。由于在海拔530米、730米、930米和1100米的高地移植复制中观察到了相似的克隆，表型可塑性可能是造成这种海拔差异的原因之一。通过相互移栽试验发现，在同一山地坡地上，冷杉对原海拔高度带表现出较强的局部适应性。因此，我们得出结论：油松的遗传适应程度低于高山油松。随后，我们利用微卫星和等位酶标记，对油菜种群间的遗传分化进行了评价，并在海拔高度检测到了与自然选择相反的非中性基因座。微卫星标记的遗传分化程度低于等位酶标记。这些微卫星座位均与环境无关。相反，仅在高山种群中检测到某些等位酶变异。以往的研究表明，高寒地区矮生居群的幼苗生长显著低于中等海拔居群。这些结果表明，高山地区的矮生种群可能与北海道中部的其他油菜种群具有不同的生态型。

Natural populations of Picea glehnii distributes in various altitudes from lowland nemoral (300m asl.) to alpine zone (1400m asl.) in central Hokkaido. We investigated morphological and physiological traits of needles from these natural populations ranging from 300m to 1400m asl.Clines along the altitude were detected in both morphological (needle density and thickness) and physiological traits (the ratio of chlorophyll a+b / nitrogen). Since the similar clines were observed in altitudinal transplant replications (530, 730, 930, and 1100m asl.), phenotypic plasticity might be one of the causes of this altitudinal differences. We found that Abies sachalinensis showed strong local adaptation to the original altitudinal zones in the same mountainous slope through the reciprocal transplant experiments. Therefore, we concluded that the extent of genetic adaptation to altitude of P. glehnii was lower than that of A. sachalinensis. Subsequently, we used microsatellite and allozyme markers, in order to evaluate genetic differentiation among populations of P. glehnii and to detect non-neutral loci against natural selection along the altitude. The extent of genetic differentiation obtained by microsatellite markers was lower than that by allozyme markers. None of microsatellite loci were related to the environment. In contrast, certain allozyme variation was detected only in alpine population. Previous studies had revealed that seedling growth from dwarf populations in alpine zones was significantly lower than that from middle-altitude populations. These findings indicated that dwarf populations in alpine zones might be different ecotype from other populations of P. glehnii in central Hokkaido.