Extinction Puzzle Explained as Selection Effect
It’s not evolution, it’s statistics. That’s the conclusion of Robert Scotland and Michael Sanderson in the Jan. 30 issue of Science. What’s the puzzle?
When biodiversity is examined in the context of species richness, a consistent feature emerges: Most taxonomic groups are species-poor, relatively few are species-rich, and the frequency distribution has the shape of a so-called “hollow curve”.
The hollow curve is a graph that looks like a letter L with a curved instead of square corner. Evolutionists have assumed that these graphs of biodiversity (numbers of species) vs. species richness (number of species per taxonomic group) tell us about evolution and extinction. Nope, say the two scientists:
We suggest that the explanation for the lack of fit between hollow curves from real data and the SBT model [their model of a “simultaneous broken tree” as opposed to the SBS, “simultaneous broken stick” model] is taxonomic, not evolutionary. Although there are no objective criteria for recognizing higher taxa, taxonomists are averse to studying genera that are either too large or too small. (Large genera are cumbersome and can be nonmonophyletic, whereas monotypic genera contain no information about relationships.) Observed hollow curves reflect a shortening of the tails of the SBT distribution. Our taxonomic explanation contrasts with evolutionary explanations, which depend on the premise that in real data sets there are too many monotypic taxa and species-rich groups that are too large. Evidence does exist for differences in speciation and extinction rates but it does not come from hollow curves.
Scotland and Sanderson, “The Significance of Few Versus Many in the Tree of Life,” Science 01/30/2004, 10.1126/science.1091483.
This is like finding the oscillating signal in the radio receiver is not from ETI but from a communications satellite. Presumably the claimed evidence for differences in speciation and extinction rates will be forthcoming in a futureware issue.