Intraspecific competition in populations of Helix aspersa with different histories of exposure to lead.
Intraspecific competition in populations of Helix aspersa with different histories of exposure to lead.
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DOI：
10.1016/s0269-7491(00)00241-4
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发表时间：
2001-10
影响因子：
8.9
通讯作者：
A. Beeby;L. Richmond
中科院分区：
文献类型：
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作者：
A. Beeby;L. Richmond
一系列无脊椎动物已经适应了某些有毒金属，因此，在存在污染物的情况下，它们的某些性能指标（通常是生长或繁殖）优于未接触的种群。在这种有毒压力下，有接触史的人群在争夺有限资源时可能会比幼稚的人群表现得更好。本研究比较了具有不同铅暴露史的六个 Helix aspersa 种群的实验室饲养幼鱼的壳生长情况。在使用两个群体的不同组合的 10 项试验中，蜗牛在 98 天的时间里争夺有限的不含 Pb 或含 500 μg/g−1Pb 的食物。每项试验由 10 名青少年组成，每个群体各 5 名，并重复四次。几乎所有提供的食物在呈现后很快就被吃掉了。每个重复中的壳生长总量（两个种群平均生长的总和）在试验之间高度一致，因此构建的壳总量受到食物供应的限制。饮食中铅的存在不会对贝壳生长造成可测量的抑制，而且在任何试验中，暴露史似乎都不会带来任何竞争优势或劣势。在其参与的每一次试验中，一个种群的增长速度始终快于其竞争对手。较小的幼鱼的壳生长往往更快。已知蜗牛的活动在高密度下会受到抑制，这可能导致高密度下个体的增量生长较低。一个群体享有的竞争优势可能主要取决于他们的活动或钙代谢。
A range of invertebrates have become adapted to certain toxic metals, such that, in the presence of the contaminant, some measure of their performance, typically growth or reproduction, is superior to that of an unexposed population. Under such a toxic stress, a population with a history of exposure might outperform a naı̈ve population in competition for limited resources. This study compared the shell growth of laboratory-bred juveniles from six populations of Helix aspersa with different histories of exposure to Pb. In 10 trials using various combinations of two populations, the snails competed for a limited supply of food that contained either no Pb or 500 μg/g−1Pb, for 98 days. Each trial consisted of 10 juveniles, five from each population and was replicated four times. Nearly all of the food provided was consumed quickly after presentation. The total amount of shell growth within each replicate (the sum of the mean growth of the two populations) was highly consistent between trials so that the total amount of shell built was limited by food availability. The presence of Pb in the diet caused no measurable depression of shell growth and exposure history did not appear to confer any competitive advantage or disadvantage in any of the trials. One population consistently grew faster than its competitors in every trial of which it was a part. Shell growth tended to be greater in smaller juveniles. Snail activity is known to be inhibited at high densities and this may have contributed to the lower incremental growth in individuals kept at the higher densities. The competitive advantage enjoyed by one population may be primarily determined by their activity or perhaps their Ca metabolism.