What’s the point?

Many plants have elaborate mechanical defenses that deter herbivory. Bactris palms, for example, have a formidable spines covering the stems and leaves. For a large mammal, no part of the plant is safe to touch, but for small insects, defenses may be evaded. Evidently the cost of building spines is outweighed by the deterrent benefit. Walking through the forest one must be very careful to not trip and fall on these trees, and be very cautious whenever a heavily defended frond falls from the sky in a windy moment.

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What is more puzzling to find is a tree with a large trunk and heavy investment in thorns. This tree, for example, is nearly a meter in diameter, and each thorn is a centimeter long. What benefit do these thorns serve? There are no large animals here, to my knowledge, that eat bark or new wood.

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Zooming in, you can see the scale of these thorns. Perhaps they are an adaptation defending against a now-extinct species, but to me it seems like there should be strong natural selection against investment in useless defense mechanisms like this one. Do you have any ideas for the origin of these structures?

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2 Comments Add yours

  1. Nick Dowdy says:

    Linkage? I am digging the blog! Keep up the good work!

    1. bblonder says:

      Thanks Nick – I hope graduate school is treating you well; keep me updated!

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