Plant Ecology Group, University of Tübingen, Auf der Morgenstelle 5, Tübingen, D-72076, Germany.
Plant Ecology and Nature Conservation, University of Potsdam, Am Mühlenberg 3, Potsdam, D-14467, Germany.
New Phytol. 2017 May;214(3):1230-1244. doi: 10.1111/nph.14436. Epub 2017 Feb 2.
Bet-hedging via between-year seed dormancy is a costly strategy for plants in unpredictable environments. Theoretically, fitness costs can be reduced through a parental environmental effect when the environment is partly predictable. We tested whether populations from environments that differ in predictability diverged in parental effects on seed dormancy. Common garden-produced seeds of the two annual plant species Biscutella didyma and Bromus fasciculatus collected along an aridity gradient were grown under 12 irrigation treatments. Offspring germination was evaluated and related to environmental correlations between generations and their fitness consequences at the four study sites. One species exhibited strong seed dormancy that increased with unpredictability in seasonal precipitation. The parental effect on seed dormancy also increased proportionally with the environmental correlation between precipitation in the parental season and seedling density in the following season; this correlation increased from mesic to arid environments. Because fitness was negatively related to density, this parental effect may be adaptive. However, the lack of dormancy in the second species indicates that bet-hedging is not the only strategy for annual plants in arid environments. Our results provide the first evidence for clinal variation in the relative strength of parental effects along environmental gradients.
通过跨年度种子休眠进行押注避险是不可预测环境中植物的一种高代价策略。从理论上讲，当环境具有一定可预测性时，通过亲代环境效应可以降低适应成本。我们检验了在可预测性不同的环境中，种子休眠的亲代效应是否存在差异。在干旱梯度上收集的两种一年生植物 Biscutella didyma 和 Bromus fasciculatus 的种群，在 12 个灌溉处理下共同生长。评估了后代的发芽情况，并将其与世代间的环境相关性及其在四个研究地点的适应度后果联系起来。一个物种表现出强烈的种子休眠性，随着季节性降水的不可预测性增加而增加。种子休眠的亲代效应也与亲代季节降水与下一季幼苗密度之间的环境相关性成比例增加；这种相关性从湿润环境到干旱环境增加。由于适应度与密度呈负相关，这种亲代效应可能是适应性的。然而，第二个物种缺乏休眠表明，押注避险并不是干旱环境中一年生植物的唯一策略。我们的研究结果首次提供了沿环境梯度亲代效应相对强度的渐变变异的证据。
