Reproductive strategies of modular organisms: Comparative studies of reef-building corals
Reproductive strategies of modular organisms: Comparative studies of reef-building corals
复制标题
DOI：
10.2307/2265514
复制
发表时间：
1996-04-01
期刊：
影响因子：
4.8
通讯作者：
Hughes, TP
中科院分区：
文献类型：
--
作者：
Hall, VR;Hughes, TP
克隆动植物的繁殖力取决于其妊娠构件（水螅、游动体、芽、分株）的数量及其繁殖产量。我们研究了六种造礁珊瑚（Acropora hyacinthus，A。nana、黑腹拟步行虫A. gemmifera、芽芽草A. millepora，Goninstrea retiformis和Stylophora pistillata），探讨模块化如何影响生殖策略和克隆动物生活史的进化。在单一的无性系生物中，繁殖力在年老时往往达到一个平台或下降。相反，我们发现，繁殖力的殖民地是不确定的，因为营养生长可以导致无限数量的重复，生殖模块。然而，群体繁殖力并不是构件数的简单线性函数。retiformis >鹿角珊瑚属> S. pistillata）与大小特异性群体生殖力（A. hyacinthus、风信子A. millepora、千孔草A. gemmifera > A. nana和G.网形）。小S. pistillata是最低的所有，但大的殖民地更肥沃的比任何其他物种在一个可比的殖民地大小（尽管Stylophora具有最低的水螅繁殖力）。这种对比清楚地表明了模块化对克隆生物生殖生物学和生活史的影响。卵和睾丸的体积以及每个息肉的卵和睾丸数量在物种之间差异很大（分别为20倍、13倍、17倍和3倍）。卵体积以S最小。pistillata（本研究中唯一的亲鱼）和G. retiformis（每个息肉的卵最多，表明卵大小和数量之间的权衡）。每个息肉（鸡蛋和睾丸相结合）的总生殖体积变化三倍之间的六个物种，并与一个类似的范围内的息肉直径。在某些情况下，水螅生殖力的组成部分取决于群体的大小; hyacinthus和A. nana和每个息肉的浮泡数。pistillata增加了2 - 4倍，菌落大小发生了1 - 2个数量级的变化。然而，卵的大小是恒定的其他物种。同样地，群体大小对每个息肉的卵或睾丸数或每个息肉的睾丸体积没有影响。我们还发现了性别分配的显着差异，这可能与这些雌雄同体物种的受精生物学有关。每个息肉的总卵体积与睾丸体积的比值变化5倍，以S最低。pistillata和G. retiformis（产生最多和最小的卵）。所有物种的这一比例都随着菌落大小的增加而增加，尤其是A.风信子早期对睾丸的投资可以使性行为开始，而不需要最初的产卵费用，也许这样菌落就可以继续生长到更大，更安全的规模。所有物种在成熟时都有一个特征性的菌落大小，在类群之间变化9倍，对应于1-3岁的最小青春期年龄。这是第一个在一系列克隆动物中同时测量雄性和雌性功能的比较研究。
The fecundity of clonal animals and plants is determined by the number of gravid modules (polyps, zooids, shoots, ramets) and their reproductive output. We examined the fecundity of modules (polyps) and colonies of six reef-building corals (Acropora hyacinthus, A. nana, A. gemmifera, A. millepora, Goninstrea retiformis, and Stylophora pistillata) to explore how modularity influences reproductive strategies and the evolution of life histories in clonal animals. In unitary, aclonal organisms, fecundity often reaches a plateau or declines in old age. In contrast, we found that fecundity of colonies was indeterminate because vegetative growth can lead to an indefinite number of repeated, reproductive modules. However, colony fecundity was not a simple linear function of the number of modules.The species ranking of polyp fecundities (G. retiformis > the Acropora species > S. pistillata) was very different from the ranks of size-specific colony fecundities (A. hyacinthus, A. millepora, A. gemmifera > A. nana and G. retiformis). Colony fecundity for small S. pistillata was the lowest of all, but large colonies were more fecund than any of the other species at a comparable colony size (despite Stylophora having the lowest polyp fecundity). This contrast highlights clearly the effects of modularity on the reproductive biology and life histories of clonal organisms.The volume of eggs and testes, and the number of eggs and testes per polyp varied greatly among species (20-, 13-, 17-, and 3-fold, respectively). Egg volume was smallest for S. pistillata (the only brooder in the study) and for G. retiformis (which also had the most eggs per polyp, indicating a trade-off between egg size and number). The total reproductive volume per polyp (egg and testes combined) varied three-fold among the six species, and was correlated with a similar range of polyp diameters. In some cases, components of polyp fecundity depended on colony size; egg size in A. hyacinthus and A. nana and the number of planulae per polyp in S. pistillata increased by two- to fourfold with a one to two order of magnitude change in colony size. However, egg size was constant for the other species. Similarly, colony size had no effect on egg or testes number per polyp or testes volume per polyp for any species.We also found striking differences in sex allocation, which may relate to the fertilization biology of these hermaphroditic species. The ratio of total egg volume to testes volume per polyp varied fivefold, and was lowest for S. pistillata (a brooder) and G. retiformis (which produced the most and smallest eggs). The ratio increased with colony size for all species, especially A. hyacinthus. An early investment predominantly in testes allows sex to commence without the initial expense of egg production, perhaps so that colony growth can continue to a larger, safer size. All species had a characteristic colony size at maturation, which varied ninefold among taxa, corresponding to a minimum puberty age of 1-3 yr. This is the first comparative study to simultaneously measure male and female function in a range of clonal animals.