Overproduction

Our sycamore tree is once again covered in developing winged seeds. Funnily enough, I haven't counted them, but there must be hundreds of thousands of the little blighters.

All living things produce more offspring than can possibly survive to maturity. Most of them will of course succumb to disease, starvation or will be eaten by some other organism.  A female salmon produces millions of eggs when she spawns. A single oyster can produce 114,000,000 eggs in a single spawning and can spawn annually for many years. In the Origin of Species Charles Darwin calculated that in the case of the elephant, one the slowest breeding land mammals, if all of the potential young of a single female survived and reproduced, and all their offspring did the same, and so on, after 750 years the descendants of this single mother could number 19,000,000! Clearly, if all of these seeds, eggs, and young survived to become adults who also reproduced, the world would soon be overrun with sycamores, salmon, oysters, elephants, and the rest. Mum and Dad have to go to an awful lot of trouble to ensure that they leave even enough living offspring to replace themselves!

In fact Darwin got his calculations wrong but that does not detract from the fundamental truth of his argument.