Predation resistance and nematocyst scaling for Metridium senile and M-farcimen
Predation resistance and nematocyst scaling for Metridium senile and M-farcimen
复制标题
DOI：
10.2307/1543587
复制
发表时间：
2004-10-01
影响因子：
1.6
通讯作者：
Francis, L
中科院分区：
文献类型：
--
作者：
Kramer, A;Francis, L
以前的研究表明，大的身体尺寸降低了捕食的风险aconatie海葵。对于两个物种的Metridium，我们发现显着增加的长度的acontial线程和未发射acontial包囊的平均长度，随着身体的大小。这支持了一个假设，即更有破坏性的乌头防御保护更大的乌头海葵免受捕食者的伤害。Metridium是嗜食性的，食物的大小不会随着身体的大小而大幅增加;所以我们预计进食触手的包囊大小会有较小的增加。事实上，在4例中有3例，腱索囊肿的标度指数明显小于同类型的腱索囊肿。这表明，可预测的选择压力，包囊缩放响应。当比较相同大小的标本时，非克隆的潮下带种M。farcimen的无肛腺泡明显大于其克隆同类M.老年，生活在东北太平洋主要潮下带捕食者的潮上限。因此，在捕食水平高的情况下，较大的无尾包囊可能特别有利。这些数据表明，密切相关的海葵物种可以区分的基础上，生态和功能相关的差异，在crystalocyst缩放。
Previous studies suggest that large body size reduces the risk of predation for acontiate sea anemones. For two species of Metridium, we found significant increases in the length of the acontial threads and in the mean lengths of the unfired acontial nematocyst capsules, with increasing body size. This supports the hypothesis that more damaging acontial defenses protect larger acontiate anemones from their predators. Metridium is planktivorous, and food size does not increase substantially with body size; so we expected smaller increases in nematocyst size for the feeding tentacles. In fact, scaling exponents were significantly smaller for the tentacle nematocysts than for acontial nematocysts of the same types in 3 out of 4 cases. This suggests that nematocyst scaling responds predictably to selection pressure. When specimens of the same size were compared, the non-clonal, subtidal species, M. farcimen, had significantly larger acontial nematocysts than did its clonal congener, M. senile, which lives at the upper tidal limits for major subtidal predators in the northeastern Pacific. Therefore, larger acontial nematocysts may be particularly advantageous where predation levels are high. These data demonstrate that closely related anemone species can be distinguished on the basis of ecologically and functionally relevant differences in nematocyst scaling.