Data from: Adaptation of diploid and tetraploid Chamerion angustifolium to elevation but not local environment

Polyploid organisms often have different geographic ranges than their diploid relatives. However, it is unclear whether this divergence is maintained by adaptation or results from historical differences in colonization. Here we conducted a reciprocal transplant experiment with diploid and autotetraploid Chamerion angustifolium to test for adaptation at the ploidy and population level. In the Rocky Mountains, pure diploid populations occur at high elevations and pure autotetraploid populations occur at low elevations with mixed-ploidy populations between. We planted 3134 seedlings in 2004 and 3890 juveniles (bolting) in 2005 among nine plots, three in each of the diploid, mixed-ploidy and tetraploid zones, and monitored survival until 2008. For both seedlings and juvenile plants, elevation significantly influenced survival. The juvenile plants also showed a significant ploidy by elevation interaction, indicating that diploids and tetraploids survived best at their native elevations. In contrast, we found no evidence of local adaptation to plot within elevation. This suggests that the current distribution of diploids and tetraploids across elevations is the result of adaptation and that genome duplication may have facilitated the invasion of lower elevation habitats by limiting the movement of maladapted alleles from diploid populations at higher elevations.多倍体生物往往与其二倍体近缘类群具有相异的地理分布范围。然而目前仍未明确，此类分布分化究竟是由适应性演化所维持，还是源于殖民历史的固有差异。本研究以二倍体和同源四倍体（autotetraploid）柳兰（Chamerion angustifolium）为实验材料，开展互易移植实验（reciprocal transplant experiment），以检验倍性与种群水平的适应性。在落基山脉地区，纯二倍体种群分布于高海拔区域，纯同源四倍体种群分布于低海拔区域，二者之间存在混合倍性种群。本研究于2004年定植3134株实生苗，2005年在9个样地内定植3890株抽薹幼株；其中二倍体区、混合倍性区与四倍体区各设3个样地，持续监测植株存活情况至2008年。无论是实生苗还是抽薹幼株，海拔均对其存活率存在显著影响。抽薹幼株还表现出显著的倍性-海拔互作效应，表明二倍体与同源四倍体在各自原生海拔区域的存活率最高。与之相对，我们未发现海拔区内样地尺度的局部适应性证据。该结果表明，二倍体与同源四倍体沿海拔梯度的当前分布格局是适应性演化的产物；同时全基因组复制可能通过限制高海拔二倍体种群中不适等位基因的扩散，促进了同源四倍体对低海拔生境的入侵。