From ScienceDaily:
One of biology’s long-standing puzzles is how so many similar species can co-exist in nature. Do they really all fulfill a different role? Massive data on beetles now provide strong evidence for the idea that evolution can drive species into groups of look-a-likes that are functionally similar.
What does it mean to say that “evolution can drive species into” … Isn’t evolution just the sum total of what happens?
For whatever reason, the article doesn’t use the term convergent evolution, though that is clearly what it is discussing:
While it is clear that species fulfill many different roles in ecosystems, it has also been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it was unclear whether such functional redundancy really exists. The new study addresses this question using extensive data on the world’s 4168 species of diving beetles. It shows that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10-20%) are rare. As body-size reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters.
Self-organization” As in a form of natural genetic (self-)engineering. But that is not a Darwinian process, and certainly not even imagined by Darwinian genetics.
Alas, the paper is a victim of the PC ‘crats in more than one way:
“This finding has important implications for how we look at the risks of losing species,” says Marten Scheffer of Wageningen University and lead author on the paper. “Our work suggests that evolution is a generator not only of functional complementarity but also of functional redundancy. However, such redundancy does not mean that these species are not needed for the functioning of nature.”
Actually that’s what the finding absolutely does mean; all those species are not needed for the functioning of nature.
Not that redundancy is an argument for driving any life form to extinction. But just to be clear, that is what the finding means. When natural selection and envirocrats get together, reasonable word use and discourse become impossible.
But Scheefer makes a very useful point here:
“It is also important to note that such resilience from functional redundancy will be much rarer in larger animals, simply because species richness decreases with body size in the animal kingdom,” Scheffer says. “It is therefore no surprise that especially the loss of large species can give rise to substantial functional change in ecosystems. While redundancy may be the rule in smaller creatures, the functional uniqueness of larger ones could imply that they are often the Achilles heel for ecological functioning.” More.
Back to the beetles for a moment, why was redundancy a puzzle anyway? A stable system typically features lots of redundancy.
Probably, the underlying Darwinian model encouraged researchers to think that one species would triumph over all the others.
But nature is not really very Darwinian, as we are discovering from many sources.
See also: Evolution: The fossils speak, but hardly with one voice for a quick rundown on what we now know.
Here’s the abstract:
While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world’s 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10–20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect. (Public access .html) – Marten Scheffer, Remi Vergnon, Egbert H. van Nes, Jan G. M. Cuppen, Edwin T. H. M. Peeters, Remko Leijs, Anders N. Nilsson. The Evolution of Functionally Redundant Species; Evidence from Beetles. PLOS ONE, 2015; 10 (10): e0137974 DOI: 10.1371/journal.pone.0137974
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