Evidence of a resource trade-off between growth and chemical defenses among Caribbean coral reef sponges
Evidence of a resource trade-off between growth and chemical defenses among Caribbean coral reef sponges
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DOI：
10.3354/meps08541
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发表时间：
2010-01-01
影响因子：
2.5
通讯作者：
Pawlik, Joseph R.
中科院分区：
文献类型：
--
作者：
Leong, Wai;Pawlik, Joseph R.
像所有生物一样，海绵将资源分配给生长和繁殖等生命功能。此外，一些海绵受到次生代谢物的保护，可以阻止潜在的捕食者。假设资源是有限的，产生防御性代谢物的物种应该分配更少的资源用于生长和繁殖。为了验证化学防御与生长之间存在平衡关系的假设，通过捕食者排除实验，比较了7种分支形态相似的加勒比常见海绵物种的生长速率，即化学防御不强的物种粘绵（Callyspongia armigera）、birotulata和Niphates erecta，以及防御强的物种Amphimedon compressa、Aplysina cauliformis、Aplysina fulva和Ptilocaulis walpersi。在9年的时间里，共对1158块海绵进行了30次野外试验，持续时间为124 ~ 195 d。采用三因素方差分析比较化学防御（不设防/设防）、治疗（非笼养/笼养）和季节（夏季/冬季）的效果。尽管不同种类的海绵对繁殖资源的分配可能不同，从而潜在地模糊了生长与化学防御之间的相互作用，但不设防的海绵在笼子中的生长显著高于设防海绵（110.4%比65.8%）。笼内和笼外化学防御海绵的生长没有差异，但笼内无化学防御海绵的生长明显大于笼外，证实了食用海绵的鱼类以美味海绵为食。与夏季相比，不设防和设防海绵在冬季的生长都明显低于夏季，但同样，不设防海绵的生长大于设防海绵。生长速率的差异表明海绵物种已经进化出了不同的分配模式来应对资源限制和捕食，并提供了与化学防御相关的代谢成本的证据。
Like all organisms, sponges allocate resources to life functions such as growth and reproduction. Additionally, some sponges are defended by secondary metabolites that deter potential predators. Assuming resources are limiting, species that produce defensive metabolites should allocate fewer resources to growth and reproduction. To test the hypothesis that there is a trade-off between chemical defense and growth, predator exclusion experiments were conducted to compare the growth rates of 7 common Caribbean sponge species with similar branching morphologies: chemically undefended species Callyspongia armigera, Iotrochota birotulata and Niphates erecta, and defended species Amphimedon compressa, Aplysina cauliformis, Aplysina fulva and Ptilocaulis walpersi. Thirty field experiments lasting 124 to 195 d were performed over a 9 yr period on a total of 1158 sponges. A 3-factor ANOVA was used to compare the effects of chemical defense (undefended/defended), treatment (uncaged/caged) and season (summer/winter). Despite the fact that different sponge species could be allocating resources differently to reproduction, thereby potentially obscuring the interaction between growth and chemical defense, growth in cages was significantly greater for undefended than defended sponges (110.4 versus 65.8% growth yr(-1)). While the growth of chemically defended sponges inside and outside of cages was not different, growth of undefended sponges inside cages was significantly greater than outside cages, confirming that palatable sponge species were grazed by sponge-eating fishes. Growth during winter months was significantly less for both undefended and defended sponges compared to growth during summer months, but again, growth was greater for undefended sponges than for defended sponges. Differences in growth rates demonstrate that sponge species have evolved alternative allocation patterns to cope with resource constraints, as well as predation, and provide evidence that there is a metabolic cost associated with chemical defenses.