Germination niche breadth and potential response to climate change differ among three North American perennials
Germination niche breadth and potential response to climate change differ among three North American perennials
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DOI：
10.1007/s12224-019-09347-2
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发表时间：
2019-06-01
影响因子：
1.2
通讯作者：
Havens, Kayri
中科院分区：
文献类型：
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作者：
Bandara, Ridma G.;Finch, Jessamine;Havens, Kayri
物种对环境变化的反应在很大程度上取决于它们的生态位宽度。为了研究萌发生态位宽度与气候变化敏感性的关系，我们选择了3种北美多年生植物：长叶Physalis longifolia， Asclepias syriaca和毛地黄Penstemon digitalis。测定了沿美国中西部纬度梯度的种群种子的休眠损失和萌发要求。新鲜种子在1、5、9、15/6、20/10、25/15和30/15℃孵育，种子在1、5和9℃冷分层，在15/6、20/10、25/15和30/15℃孵育4-12周，根据最终发芽比例计算萌发生态位宽度（Levins’B-n）。此外，通过温度序列评估了未来变暖对种子萌发物候的影响。不同种群和不同采集纬度的种子萌发率差异显著（P < 0.001），但差异不具有纬向特征。生态位宽度以羊绒属和羊绒属最宽，以盆草属最窄（P = 0.05），与萌发物候有关。北方采集区在未来增温条件下，棉草和羊草的发芽期向秋季转移，而播草的发芽期向春季提前转移。由于层积和萌发要求有限，导致生态位宽度最窄，我们最初预测彭菖蒲是最危险的，因为未来的变暖将超出其层积包膜。然而，生态位宽度较宽的物种（Physalis和Asclepias）可能由于萌发物候的不适应变化而更容易受到气候变化的影响。
Responses of species to environmental change are largely dependent on their niche breadth. To investigate the relationship between germination niche breadth and sensitivity to climate change, we selected three North American perennials: Physalis longifolia, Asclepias syriaca and Penstemon digitalis. Dormancy loss and germination requirements were determined for seeds from populations along a Midwest US latitudinal gradient. Fresh seeds were incubated at 1, 5, 9, 15/6, 20/10, 25/15 and 30/15 degrees C, and seeds cold stratified at 1, 5 and 9 degrees C for 4-12 weeks were incubated at 15/6, 20/10, 25/15 and 30/15 degrees C. Germination niche breadth (Levins' B-n) was calculated from final germination proportion. In addition, a sequence of temperatures evaluated the effect of future warming on germination phenology. Germination differed significantly among populations and collection latitudes (P < 0.001), but variation did not have a latitudinal pattern. Niche breadth was widest for Physalis and Asclepias and narrowest for Penstemon (P = 0.05), with implications for germination phenology. Germination shifted to autumn for Physalis and Asclepias under future warming in northern collection regions, and shifted earlier in spring for Penstemon regardless of region. Due to limited stratification and germination requirements, resulting in the narrowest niche breadth, we initially predicted Penstemon to be most at-risk, as future warming would fall outside its stratification envelope. However, species with wide niche breadths (Physalis and Asclepias) may bemore vulnerable to climate change due to maladaptive shifts in germination phenology.