Search Theory, Random Motion, and the Convergent Evolution of Pollen and Spore Morphology in Aquatic Plants
Search Theory, Random Motion, and the Convergent Evolution of Pollen and Spore Morphology in Aquatic Plants
复制标题
水生植物花粉和孢子形态的搜索理论、随机运动和趋同演化
作者：
P. Cox
对随机运动的本质和随机搜索理论的考虑表明，对于具有长轴且在平面上（如在水面上）移动的水生孢子，而不是在三维空间中移动的孢子，搜索效率要高得多。由于这种适应也增加了近亲繁殖的风险，因此预计在水生环境中雌雄异株的发生率更高。这些预测得到了对各种不相关被子植物、蕨类植物、苔藓植物和真菌的水生孢子的汇编数据的支持。几乎所有的水生孢子都被发现具有相对于非水生孢子的非常大的长轴，或者在具有大长轴的搜索工具中运输。许多孢子被发现有漂浮装置，许多分类群被发现是雌雄异株。我的结论是，这些趋势在水生孢子形态可以最好地解释为收敛进化向一个有效的搜索工具。几个可供选择但并非相互排斥的假设也被检验作为这种明显趋同的潜在解释。
A consideration of the nature of random motions and the theory of random search suggests that search efficiencies would be much greater for aquatic spores with large long axes and which move in planes, such as at the water surface, rather than in three dimensions. Since such adaptations also increase the risk of inbreeding a greater incidence of dioecism is predicted in aquatic environments. These predictions are supported by data compiled on the aquatic spores of a variety of unrelated angiosperms, pteridophytes, bryophytes, and fungi. Nearly all aquatic spores were found to have either extremely large long axes relative to nonaquatic spores, or to be transported in search vehicles with large long axes. Many spores were found to be equipped with flotation devices, and many of the taxa were found to be dioecious. I conclude that these trends in aquatic spore morphologies can best be explained as convergent evolution toward an efficient search vehicle. Several alternative, but not mutually exclusive, hypotheses are also examined as potential explanations for this apparent convergence.