This article trumpets a startling lead: “Charles Darwin may have been wrong when he argued that competition was the major driving force of evolution.”
“Space is the final frontier for evolution, study claims” -BBC News
Professor Michael Benton of Bristol University makes his pot-stirring mission abundantly clear by stating outright “Competition did not play a big role in the overall pattern of evolution.”
This conclusion is not supported by the original paper (written by his grad students) or its data, and I feel comfortable saying that Professor Benton is deliberately misrepresenting modern evolutionary theory in order to create fake controversy and gain publicity for himself.
This is a bold statement, so I will back it up.
The abstract of the original paper can be found here:
Biol Lett. 2010 Aug 23;6(4):544-7. Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land. Sahney S, Benton MJ, Ferry PA.
Sahney et. al. conclude: “These groups [amphibians, reptiles, and mammals] have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.”
That is a much less startling piece of information than “Darwin may have been wrong!” To quote the BBC article, “The new study proposes that really big evolutionary changes happen when animals move into empty areas of living space, not occupied by other animals.”
But what happens after the animals arrive? And why are they moving into new empty areas in the first place?
The answer: competition.
First, competition is why animals move into empty niches (“ecospaces” is apparently the trendy new term) in the first place. If animals weren’t competing for scarce resources, they wouldn’t move into new niches when they became available: they’d simply stay where they are. As Professor Stearns put it so eloquently when tasked with the token skeptical quote, “What is the impetus to occupy new portions of ecological space if not to avoid competition with the species in the space already occupied?”
Second, when plants or animals expand into a new niche, the short-term effect is indeed that the level of competition drops, and many individuals survive who would not have survived before. (Example: It’s not useful to be a lion in a world with T. Rex and Utahraptor, so mammals remained small—but once the dinosaurs died, mammals could become larger and more predatory without immediate penalty.) However, this is a temporary situation, and soon the new ecospace fills with animals—albeit with more variations than before. Then, as the new ecospace fills up, selection pressure becomes greater again, the unfit variations perish, and the fit variations survive.
If there were no competition, there would be no speciation at all, because there would be no differential survival…just a slowly diffusing cloud of randomly varying animals. Furthermore, since there are far more unsuccessful variations than successful variations, the selection pressure of competition directs variation into useful phenotypes—actually increasing the rate of evolutionary change as each generation is selected for more successful adaptation to their new ecospace.
Finally, let us examine the notion of “ecospace”. (A word synonymous with “niche” in the existing literature.) What is an “ecospace”, anyway, and what defines it? Part of it is inanimate geological features: rivers, oceans, mountains, rocks. But most of an ecospace is…other creatures. On land, an ecospace contains soil microbes, fungi, flora, worms, and nematodes. It contains grasses, bushes, trees, fungi, ferns, vines, mosses, and lichens. It contains insects, snakes, rodents, birds, cats, dogs, apes, and all manner of crawling, digging, hopping, tunneling, and flying creatures.
As Richard Dawkins explains very clearly in his masterwork “The Extended Phenotype“, the expression of an animal’s genes go beyond its physical body. A termite nest is just as much an expression of termite genes as the termite’s legs or head. A beaver’s dam is an expression of beaver genes, herding and grazing behavior is an expression of antelope genes, forests are an expression of tree genes, and roads and cities are expressions of human genes. In short, an “ecospace” is, in large part, an expression of the genes of the organisms that live in it.
Therefore, it is meaningless to speak of “expansion and contraction of ecospace” in the passive voice, as if this has nothing to do with the actions and consequent differential survival (i.e. competition) of the creatures within it. Yes, change can be imposed from without by asteroids or glaciers…but it can also be imposed by a change in the other living things that make up the ecospace. To pick the most obvious example, humans have dramatically changed the ecospace of the Earth, most particularly over the last 10,000 years since the advent of agriculture.
In conclusion, we can easily see that diversity is indeed increased by changes in ecospace—but only as long as the underlying mechanism of Darwinian competition remains.
Furthermore, we can easily see that Professor Benton’s claim that “Competition did not play a big role in the overall pattern of evolution” is nonsense.
