THE PARADOX OF ROCKALL - WHY IS A BROODING GASTROPOD (LITTORINA-SAXATILIS) MORE WIDESPREAD THAN ONE HAVING A PLANKTONIC LARVAL DISPERSAL STAGE (LITTORINA-LITTOREA)
THE PARADOX OF ROCKALL - WHY IS A BROODING GASTROPOD (LITTORINA-SAXATILIS) MORE WIDESPREAD THAN ONE HAVING A PLANKTONIC LARVAL DISPERSAL STAGE (LITTORINA-LITTOREA)
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DOI：
10.1007/bf00392558
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发表时间：
1988-01-01
期刊：
影响因子：
2.4
通讯作者：
JOHANNESSON, K
中科院分区：
文献类型：
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作者：
JOHANNESSON, K
在底栖无脊椎动物中，通常认为，将浮游幼虫扩散比将成虫或卵块漂流更有效。当然，在短距离内，即，在几十公里或更短的范围内，寿命较长的营养幼虫是一种有效的扩散机制。然而，湍流混合和死亡率会降低的浓度，以及在一定的距离从祖先的人口定居者的密度可能太低，使未来的低流动性的成年人之间的交配。另一方面，长距离漂流的成鱼、幼鱼或底栖卵块可能会移殖到新的生境。关键点是生物体的幼虫发育类型。如果创始群体属于一个直接发育的物种，或者是一个产生寿命很短的幼虫的物种，那么所有生命阶段的低流动性将使种群保持在一个有限的区域内，这样即使在一个小种群中，配偶也可能彼此相遇。即使底栖动物阶段的迁移很少发生，这可能比幼虫远距离扩散更有影响力。为了表明这可能是真的，详细的地理分布的两个潮间带腹足类物种的发展模式的对比，并进一步支持这一假设的文献进行了讨论。
In benthic invertebrates dispersal of planktotrophic larvae is generally considered more effective than is, for example, the rafting of adults or egg masses. It is certainly true that over short distances, viz., in the range of tens of kilometres or less, a moderately long-lived planktotrophic larva represents an effective mechanism of dispersal. However, turbulent mixing and mortality will decrease the concentration of planktotrophic larvae, and at some distance from the ancestral population the density of settlers may be too low to enable future matings between adults of low mobiliity. On the other hand, adults, juveniles or benthic egg masses drifted over long distances may colonize new habitats. The crucial point is the type of larval development of the organism. If the founder group belongs to a species with direct development or which produces very short-lived planktonic larvae, the low mobility of all life-stages will maintain a population within a restricted area so that mates will be likely to encounter each other even in a small population. Even if transport of benthic stages happens very rarely, this may be more influential than larval dispersal over long distances. To show that this may be true the detailed geographical distribution of two intertidal gastropod species with contrasting modes of development is presented and further support from the literature for this hypothesis is discussed.