Synergistic effects of multiple mechanisms drive priority effects within a tadpole assemblage
Synergistic effects of multiple mechanisms drive priority effects within a tadpole assemblage
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DOI：
10.1111/j.1600-0706.2011.19221.x
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发表时间：
2012-02-01
期刊：
影响因子：
3.4
通讯作者：
Chalcraft, David R.
中科院分区：
文献类型：
--
作者：
Hernandez, Jason P.;Chalcraft, David R.
越来越多的证据表明，物种到达某个地区的历史可能对物种的表现产生重要影响，但产生优先影响的机制并不总是明确的。青蛙蝌蚪发育时间的差异提供了一个机会来研究优先效应可能影响晚到分类单元的适应性成分的机制。具体来说，南方豹蛙（Rana）的蝌蚪通常需要一年多的时间才能完成变态，因此它们在池塘中越冬，并在春天与新产下的蝌蚪竞争。我们在人工池塘中进行了一项实验，以评估越冬林蛙蝌蚪影响春季放入池塘的南方蟾蜍（Bufo）蝌蚪健康成分的机制。我们发现越冬的林蛙会降低蟾蜍的性能，而与蟾蜍同时进入池塘的新孵化的林蛙则不会。这种优先效应的产生主要是由于林蛙在蟾蜍到来之前的冬季耗尽了池塘中的藻类资源。蟾蜍的表现与春季池塘中藻类丰度的变化并不相符，我们发现的证据表明，在冬季缺乏资源开发的情况下，越冬林蛙在春季当两种物种同时出现时，不会与蟾蜍激烈竞争。然而，当林蛙在冬季耗尽藻类资源时，林蛙和蟾蜍之间在春季的相互作用就变得更加重要，因为蟾蜍的发育速度和存活率下降的程度比仅通过资源开发所预测的要大。我们的结果表明，优先效应可能是由于早期殖民者在其他物种到来之前耗尽了可用资源，这可能会加剧物种共存时的行为/物理相互作用。
Mounting evidence suggests that the history of species arrival to a locality can have important effects on species performance but the mechanism(s) through which priority effects are produced is not always clear. Differences in the developmental time of frog tadpoles provide an opportunity to examine mechanisms through which priority effects may influence fitness components of a late arriving taxon. Specifically, tadpoles of the southern leopard frog (Rana) can often require more than a year to complete metamorphosis so they overwinter in a pond and compete with newly deposited tadpoles in the spring. We conducted an experiment in artificial ponds to evaluate mechanisms through which overwintering Rana tadpoles influence fitness components of southern toad (Bufo) tadpoles deposited into ponds during the spring. We found that overwintered Rana reduced Bufo performance while newly hatched Rana that enter a pond simultaneously with Bufo did not. The production of this priority effect was primarily the result of Rana depleting algal resources in a pond during the winter prior to Bufo arrival. The performance of Bufo did not correspond with variation in the abundance of algae present in a pond during the spring and we found evidence to indicate that, in the absence of resource exploitation during the winter, overwintered Rana do not compete strongly with Bufo during the spring when both species co-occur. When Rana deplete algal resources during the winter, however, interactions between Rana and Bufo during the spring became much more important as both the development rate and survival of Bufo was reduced to a greater extent than what would have been predicted by resource exploitation alone. Our results demonstrate that priority effects can result from early colonists depleting resource availability prior to the arrival of other species which can intensify behavioral/physical interactions between species when they co-occur.