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 50 seed shadow DHJanzen101272.jpg high resolution
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When the population of a species of plant is very large, it in turn produces enormous numbers of seeds. With such a dense seed shadow, seeds fall in every conceivable place. For example, there is an Opuntia repens - a ground-dwelling opuntia - growing in the upper fork of this acacia tree (not an ant-acacia) on Greater St. James Island. This means that through multiple tries, seeds and therefore seedlings and even therefore adults end up in places where the plants would never be found in a mainland habitat full of competitors and predators. It is easy to see how this relaxed selection can be the first step in the evolution of new species with different life forms. By its microlocation, this seedling also suggests that the seeds of this very abundant opuntia are dispersed by birds. |
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