Acorn defenses to herbivory from insects : Implications for the joint evolution of resistance, tolerance and escape
Acorn defenses to herbivory from insects : Implications for the joint evolution of resistance, tolerance and escape
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DOI：
10.1016/j.foreco.2006.10.024
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发表时间：
2007-01
影响因子：
3.7
通讯作者：
Zhishu Xiao;M. Harris;Zhibin Zhang
中科院分区：
文献类型：
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作者：
Zhishu Xiao;M. Harris;Zhibin Zhang
以栓皮栎（Quercus variabilis）、栓皮栎（Quercus variabilis）和栎属（Quercus variabilis）3个伴生栎属树种为研究对象，研究了昆虫对橡子的捕食作用及其对橡子成苗的影响。serrata和青冈（Cyclobalanopsisglauca）的种间差异显著。所有栎属的单宁含量均较高（均在10%以上），但在橡子质量和发芽时间上存在差异。我们假设橡子的防御特性（如种子质量、单宁和发芽时间）共同作用以减少昆虫种子捕食者的伤害。Q. variabilis的捕食率（51.2%）显著低于Q.锯齿状（71.4%）或C.青灰色占73.8%。随着伤害程度的增加，所有栎属树种的成苗率均下降。尽管由于昆虫种子捕食者造成了大量的橡子死亡，但多达43%的昆虫侵染的橡子发芽并建立为可存活的幼苗。种子质量较大的Q. variabilis表现出耐受昆虫侵染并保持足够的贮藏量用于种子萌发和幼苗的早期生长。秋发芽也有利于Q. variabilis 和Q.锯齿状，通过快速的储备转变为成熟橡子的立即发芽，从而逃避昆虫取食的直接和辅助作用。研究结果表明，种子质量大、单宁含量高和秋季萌发共同作用，可减轻昆虫对种子的捕食效应，橡子的抗性和耐受性的联合进化（以及通过秋季萌发的逃逸）可能是橡子与昆虫捕食者相互作用的部分选择结果。
Acorn predation by insects and its effects on seedling establishment were investigated among three co-occurring oak species (Quercus variabilis, Q. serrata and Cyclobalanopsis glauca) in a subtropical evergreen broadleaved forest, Southwest China. All oak species had high tannin concentration (over 10%) but differed in acorn mass and germination schedule. We hypothesized that the defensive traits in acorns (e.g. seed mass, tannins and germination schedule) act together to reduce damage from insect seed predators. Q. variabilis had significantly lower predation (51.2%) than either Q. serrata (71.4%) or C. glauca (73.8%). Seedling establishment decreased with increasing injury for all oak species studied. As much as 43% of insect infested acorns germinated and established as viable seedlings despite extensive acorn mortality due to insect seed predators. The larger seed mass of Q. variabilis appears to tolerate insect infestation and retain enough stored reserves for seed germination and early growth of seedlings. Autumn germination also benefited Q. variabilis and Q. serrata, allowing escape from both direct and ancillary effects of insect feeding by fast reserve shifting to immediate germination of mature acorns. Our results indicate that large seed mass, tannin and autumn germination act together to ameliorate effects of insect seed predation, and the joint evolution of resistance and tolerance (as well as escape through autumn germination) in acorns may be the selective consequences driven in part by interactions with insect seed predators.