Predator satiation and extreme mast seeding in 11 species of Chionochloa (Poaceae)
Predator satiation and extreme mast seeding in 11 species of Chionochloa (Poaceae)
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DOI：
10.1034/j.1600-0706.2000.900306.x
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发表时间：
2000-09-01
期刊：
影响因子：
3.4
通讯作者：
Schauber, EM
中科院分区：
文献类型：
--
作者：
Kelly, D;Harrison, AL;Schauber, EM
新西兰 11 种 Chionochloa（禾本科）的 16 个长数据集描述了每年开花情况的变化。所有种群都表现出极端的肥大播种。变化最大的物种是 C. crassiuscula（变异系数，CV = 3.02），在峡湾地区的塔卡河谷已有 26 年的历史，这是我们所知的世界范围内已发表的最高的 CV。其他种群也具有较高的 CV（最低 CV = 1.42，平均 CV = 1.84），高于其他经过充分研究的属，如云杉属、松属和栎属。也存在频繁的零开花年份（所有种群的平均零年率为 37.2%；C. rubra 和 C. crasiuscula 在 19 年中最高为 53%），而零年开花在其他已发表的肥大数据集中很少见。同一地点内的物种之间的开花高度同步（平均 r = 0.886），以及地点之间的开花高度同步（尽管明显较少）。在位点之间，种内同步性（平均 r = 0.711）并不显着高于种间同步性（r = 0.690）。夏季温暖的气温导致第二年夏天开花繁盛。开花同步性随着当地去季节夏季温度同步性的增加而增加，并随着地点之间距离的增加而减少。在 Chionochloa 中，肥大播种已被证明可以减少专业鲍尔或种子捕食者的损失。如果物种拥有共同的种子捕食者，那么物种间的同步性可能是适应性的。至少有 10 种 Chionochloa 物种正在发育的种子受到一种未描述的瓯孢子虫 (cecidomyiid) 幼虫的攻击。在塔卡河谷，那里的肥大现象最为明显，在所有四年的研究中，瓮虫攻击了所有六种 Chionochloa 物种。年平均损失几乎保持不变（10.0% 至 13.4%），而开花效果却变化了 100 倍。不变的损失与其他证据一致，表明粳母可能延长了滞育期，这将使其更难以通过肥大播种来满足。我们假设，有利于 Chionochloa 如此高水平的肥大播种的一个可能因素是其种子捕食者很难满足。
Variation in annual flowering effort is described for 16 long datasets from 11 species of Chionochloa (Poaceae) in New Zealand. Ail populations exhibited extreme mast seeding. The most variable species was C. crassiuscula (coefficient of variation, CV = 3.02) over 26 years at Takahe Valley, Fiordland, which is the highest published CV we know of worldwide. The other populations also had high CVs (lowest CV = 1.42, mean CV = 1.84) which were higher than for other well-studied genera such as Picea, Pinus and Quercus. There were also frequent years of zero flowering (mean across all populations was 37.2% zero years; maximum 53% for C. rubra and C. crassiuscula over 19 years) whereas zero years are rare in other published masting datasets.Flowering was highly synchronous among species within a site (mean r = 0.886), and also (though significantly less so) among sites. Among sites, synchrony was not significantly higher within-species (mean r = 0.711) than between-species (r = 0.690). Warm summer temperatures led to heavy flowering the following summer. Flowering synchrony increased with increasing synchrony in local deseasonalised summer temperatures, and decreased with increasing distance between sites. Mast seeding has been shown in Chionochloa to reduce losses to specialist Bower or seed predators. Among-species synchrony may be adaptive if species share a common seed predator. Developing seeds of at least 10 Chionochloa species are attacked by larvae of an undescribed cecidomyiid. In Takahe Valley, where masting is most pronounced, cecidomyiids attacked all six Chionochloa species in all four years studied. Mean annual losses were almost constant (10.0 to 13.4%) while flowering effort varied 100-fold. The invariant losses are consistent with other evidence that the cecidomyiid may have extended diapause, which would make it harder to satiate by mast seeding. We hypothesise that one possible factor favouring such extremely high levels of mast seeding in Chionochloa is that its seed predator is very hard to satiate.