For me, the importance of this piece in Nature is not so much that, by assuming what is to be proven, it is possible to demonstrate the obvious (that heavily spined fish will not have an advantage where there are no predators). The significance is that this trivial example of existing trait filtering and selection is then touted as a major discovery of Natural Selection at work in the fossil record. Is this not an admission that microevolution is the best that the fossil record ever shows?
Evolutionary biology: Darwin in the fossils Andrew P. Hendry (heavily edited excerpts)
“Although adaptation by natural selection is thought to drive evolution, it has been difficult to confirm this process in the fossil record. The evidence has been there all along; we just haven’t been looking properly.
Statistical analyses of fossil data generally fail to confirm that natural selection strongly influences morphological evolution. Taken at face value, these results might suggest that organisms have evolved their distinctive phenotypes without much aid from directional selection and that Darwinian mechanisms might not be particularly important in generating the diversity of life.
In a series of fossil fishes from Nevada, Bell found that the existing methods inferred randomness almost every time. We have a pattern that is logical and manifestly obvious but cannot be confirmed by statistics. Bell concludes “current methods to study rates or patterns of phenotypic evolution in the fossil record are strongly biased against detecting directional selection”.
Hunt refined the existing methods and used these methods to provide strong support for directional selection in the stickleback fossils. Their analysis is akin to a positive control in showing that a new statistical method can infer the correct evolutionary process when that process is almost certain to be acting.
The retreat from a ‘one model to rule them all’ vision will almost certainly generate additional support from fossil sequences for the action of natural selection.”
Nature 451, 779-780 (14 February 2008) | doi:10.1038/451779a