Guzmán Adriana, Stevenson Pablo R
Fundación Malpelo y Otros Ecosistemas Marinos, Carrera 7 No. 32-33, piso 27. Bogotá, Colombia.
Rev Biol Trop. 2011 Dec;59(4):1795-803.
Most studies on seed dispersal in time have focused on seed dormancy and the physiological triggers for germination. However, seed dispersed by animals with low metabolic and moving rates, and long gut-passage times such as terrestrial turtles, could be considered another type of dispersal in time. This study tests the hypothesis that seeds dispersed in time may lower predation rates. We predicted that seeds deposited below parent trees after fruiting fall has finished is advantageous to minimize seed predators and should show higher survival rates. Four Amazonian plant species, Dicranostyles ampla, Oenocarpus bataua, Guatteria atabapensis and Ocotea floribunda, were tested for seed survival probabilities in two periods: during fruiting and 10-21 days after fruiting. Experiments were carried out in two biological stations located in the Colombian Amazon (Caparú and Zafire Biological Stations). Seed predation was high and mainly caused by non-vertebrates. Out of the four plant species tested, only Guatteria atabapensis supported the time escape hypothesis. For this species, seed predation by vertebrates after the fruiting period increased (from 4.1% to 9.2%) while seed predation by non-vertebrates decreased (from 54.0% to 40.2%). In contrast, seed predation by vertebrates and by non-vertebrates after the fruiting period in D. ampla increased (from 7.9% to 22.8% and from 40.4% to 50.6%, respectively), suggesting predator satiation. Results suggest that for some species dispersal in time could be advantageous to avoid some type of seed predators. Escape in time could be an additional dimension in which seeds may reach adequate sites for recruitment. Thus, future studies should be address to better understand the survival advantages given by an endozoochory time-dispersal process.
大多数关于种子在时间上传播的研究都集中在种子休眠以及萌发的生理触发因素上。然而，由代谢率低、移动速度慢且肠道通过时间长的动物传播的种子，比如陆龟传播的种子，可被视为另一种在时间上的传播类型。本研究检验了这样一个假设，即种子在时间上的传播可能会降低被捕食率。我们预测，在果实掉落结束后沉积在母树下的种子有利于将种子捕食者降至最低，并且应该具有更高的存活率。对四种亚马逊植物物种，即大叶叉柱花、巴塔乌油棕、阿塔巴彭斯瓜馥木和多花樟，在两个时期测试了种子存活概率：结果期和结果后10 - 21天。实验在位于哥伦比亚亚马逊地区的两个生物站（卡帕鲁和扎菲尔生物站）进行。种子捕食率很高，主要是由无脊椎动物造成的。在测试的四种植物物种中，只有阿塔巴彭斯瓜馥木支持时间逃避假说。对于该物种，结果期后脊椎动物对种子的捕食增加了（从4.1%增至9.2%），而无脊椎动物对种子的捕食减少了（从54.0%降至40.2%）。相比之下，大叶叉柱花结果期后脊椎动物和无脊椎动物对种子的捕食都增加了（分别从7.9%增至22.8%和从40.4%增至50.6%），这表明存在捕食者饱和现象。结果表明，对于某些物种来说，在时间上的传播可能有利于避免某种类型的种子捕食者。时间逃避可能是种子到达适宜定居地点的一个额外维度。因此，未来的研究应致力于更好地理解内果皮传播时间过程所带来的存活优势。
