Creator of keystone:
I often introduce my topic by saying that a population of any animal must limit its gene pool size or ultimately speciation effects will wipe it out. This could take a couple of thousand generations, but evolution preempts the issue by creating one or more mechanisms to keep the population below a thousand by drastically lowering fertility if there is mating with very distant relatives for more than a few generations. Then I go on to say that without such mechanisms the whole population would go extinct. At this point I have generally lost my audience but I go on with, “And if it is a keystone species, the whole ecosystem will collapse.” That generally finishes off the most indulgent listener.
I used to squirm a bit. I mean I understood what a keystone species was. It was a species critical to the existence of an eco system. Take a coral reef, for instance. Take away the coral and hosts of other species that would hang around no longer hang around. But as I read the literature it seemed to me that there was a sense of uncertainty. Finally somebody had evidence that the grasslands of the northern planes were due to the foraging and fertilization by mammoths. That’s good, although a single instance does not really establish a general principle.
Well life is good. There is now an article (Ed Yong Dynasty [I suppose in contradistinction with “die wholesome”] NATURE vol. 493 no. 7432 January 17, 2013 page 286) that tells who invented the term; it was Bob Paine. And it describes his original evidence. He selected 8 meters – call it 26 feet – of rocks along the Pacific Northwest Coastline and removed the starfish, on this occasion ochre sea star, using a crowbar and threw them as far out to sea as he could. Then he watched what happened. Over a period of time barnacles, upon which the starfish feasted, overran the zone, crowding out limpets, anemone and algae. That left the mussels, which duly crowded out the barnacles until only mussels were left. Bang goes the ecosystem.
Of course what I noticed chiefly was that the starfish, each up to half a meter across, did not simply swarm in to exploit the newly available barnacles. That means a single starfish was unlikely in the course of twelve hours (he had to remove them at low tide) to travel the distance from edge to center of 4 meters, eight times its arm spread. Think of a man not moving more than eight times his six foot arm span or 24 feet from his couch over the same period. That would be serious couch potato behavior. Well I knew animals were territorial, but that seems ridiculous. Even top predators may not much go aroving.
The article goes on to mention sea otters, wolves, grey whales and spotted bass. Swimming in the ocean might get a lot more exciting if the sperm whales, which are the only predators on giant squid I know of, were to vanish for long enough.
The articles main interest is in the man’s influence, whom he trained and whom they trained and so forth. A graphic to that effect is very impressive. But for me it’s nice to know that the keystone species idea – once revolutionary – has broad support. It helps with my hype.
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