"Instant" Evolution Seen in Darwin's Finches, Study Says #7

"Instant" Evolution Seen in Darwin's Finches, Study Says, National Geographic, Mason Inman, July 14, 2006 ...

[Graphic: Directional Selection - Galapagos Finches, Dr. Jay Pitocchelli, Saint Anselm College.

Continued from part #6]

.... The situation reached a tipping point when a severe drought hit the island in 2003 and 2004. Both finches suffered, since there were far fewer seeds overall. The dominant large ground finch ate most of the available large seeds. "With the near removal of the supply of large seeds, the large-beaked birds [among] the medium ground finches did not have enough food to survive," Peter Grant said. "They died at a faster rate than the small-beaked members of the population." [Again this cycle of species adapting to the local environment must have happened tens of thousands of times in the past "two to three million years" when the finches "ancestral species ... arrived from the South American mainland," with no net change (after the initial adaptive radiation into between 6 and 14 species)!

In fact, if there has been any net change it is negative, in the sense that there is evidence that there once were more finch species on the Galapagos, as "there are two forms [of Geospiza magnirostris] which have not been recorded since 1835" and "Also among the Beagle specimens are two which ...belong to an unknown form related to the sharp-beaked groundfinch G. difficilis":

"Nearly all the finches collected by Charles Darwin are similar in appearance to those taken by later collectors, but there are two forms which have not been recorded since 1835. First, there are three male and four female specimens obviously referable to the large ground-finch Geospiza magnirostris, but which are considerably larger than any collected since. ... while it would be pleasing to demonstrate measurable evolution on the basis of specimens collected by Darwin, it seems far more probable that these large birds represent an extinct subspecies of G. magnirostris from Charles, where the bird no longer resides. ... Also among the Beagle specimens are two which in my opinion belong to an unknown form related to the sharp-beaked groundfinch G. difficilis. They have a similar shape of beak, though the beak is larger." (Lack, D., "Darwin's Finches: An Essay on the General Biological Theory of Evolution," [1947], Harper Torchbooks: New York NY, 1961, reprint, pp.22-23) ]

The effects of competition are apparent when this event is compared to a drought in 1977, before the large ground finch arrived on the island, the researchers argue. During the earlier drought the medium ground finches' average beak size actually increased. [Who would even bother to "argue" that finch beak size tracks the size of the available seeds? The only things to "argue" about are:

1) is "the medium ground finches' average beak size" increase (i.e. cyclical fluctuation of increase and decrease-since this has been happening for "two to three million years") due to Darwinian natural selection of random micromutations or phenotypic plasticity? and

2) if the former, then this is evidence of the limitations of the Darwinian mechanism, because presumably the same cycle of: a) the large ground finch, G. magnirostris, arriving on Daphne Major; b) the ensuing competition for the larger seeds causing the medium ground finch, G. fortis to specialise on smaller seeds; c) causing the average size of G. fortis' beak to decrease; has happened tens of thousands of times in the past "two to three million years"); or

3) if the latter, then another "icon" of evolution will have to be quietly dropped from the texbooks, with the added embarrassment that these are Darwin's finches! Either way, there is nothing in this for Darwinism!]

... Jonathan Losos is an evolutionary ecologist at Harvard University in Boston, Massachusetts, who was not involved with the Grants' work. [It was Losos' study on increases in the leg length of Anolis lizards in the Bahamas, in which he concluded that "Macroevolution may just be microevolution writ large -- and, consequently, insight into the former may result from study of the latter" that was criticised by Stephen Jay Gould as "irrelevant" to long-term change in his "Paradox of the Visibly Irrelevant."]

"This study will be an instant textbook classic," he said. [Losos does not say what this "will be an instant textbook classic" of. In his own own Anolis lizard leg length increase paper, he did not argue it was due to "natural selection" but instead claimed it was due to "phenotypic plasticity":

"Whether or not they provide the long-sought smoking gun of evolution, the experiments of Losos, Warheit and Schoener [Losos, J. B., et al., "Adaptive differentiation following experimental island colonization in Anolis lizards," Nature, Vol. 387, 1997, pp.70-73] have the potential to explore the mechanism(s) underlying the processes of adaptation. Darwin's use of `natural selection' is normally considered to mean the sorting of genetic-based variation within a particular environmental context. The authors of the paper do not use the term. Nor do they consider the short-term directional change observed in these lizards to be evidence for founder effect or genetic drift. Instead, the authors of this exciting Anolis study present it as a possible demonstration of the potential `macroevolutionary significance' of `phenotypic plasticity.' They argue for the `adaptive importance of nongenetic environmental effects on morphological size and shape of animals.' By this they appear to mean that if Anolis can adapt rapidly to new environments without the introduction of new genetic variation, perhaps the mode of rapid evolution required for punctuated equilibrium is a possibility. This less-than-traditional interpretation owes more to the ideas of Waddington (for example, genetic assimilation) or Schmalhausen than to the classical population genetics of Dobzhansky." (Thomson, K.S., "Natural Selection and Evolution's Smoking Gun," American Scientist, Vol. 85, No. 6, November-December 1997, p.518)]

"The most intriguing aspect of the study is its nuanced understanding of how and when character displacement occurs," Losos added. [See above re what Losos may mean by "how ... character displacement occurs"!]

"It supports suggestions by the Grants and others that [natural] selection will be most intense during crunch times." [Perhaps Losos is now arguing for natural "selection"? Whatever, Gould included "Darwin's finches of the Galapagos Islands" with "Losos's study on lizard legs" in his examples of visible irrelevance to long-term change."

The point is that if "natural selection" is "most intense during crunch times" (and who would even bother denying that), it then is least "intense" during non- "crunch times," with a net effect of stasis, i.e. no change, just oscillation around a mean (as the above graphic of so-called "directional selection" shows).

Indeed, if anything, the evidence above of extinction, and "fusing" (indicating that they are not true species, but are "as Darwin feared" a "hybrid swarm" of "marked varieties"):

"Peter Grant, Rosemary Grant and their students stand at the other extreme of Galapagos researchers-returning time and again for decades. They too continually find new things. For example, the Grants' increasing recognition of crossbreeding among Darwin's finches suggests that hybridization plays a larger role in evolution than was previously thought. Galapagos ground finches do breed across species, the Grants find, and their hybrid offspring can thrive where conditions favor intermediate types. `The discovery of superior hybrid fitness over several years suggests that the three study populations of Darwin's finches are fusing,' they note, `and calls into question their designation as species.' [Grant, P.R. & Grant, B.R, "Hybridization of Bird Species," Science, Vol. 256, 1992, pp. 193-197] Under strict phylogenetic or breeding-population definitions of species, Peter Grant concludes, only six separate species of Darwin's finches may exist, not the traditional fourteen. Owing to these findings, made more than half a century after David Lack's landmark study, Ernst Mayr once again wonders whether Darwin's finches offer a textbook case of adaptive radiation [Mayr, E.W., Interview with author, 20 April 2000, Cambridge MA]. The ground finches may indeed constitute a `hybrid swarm' with marked varieties, much as Darwin feared and pre-Lack ornithologists surmised. [Lowe, P., "The Finches of the Galapagos in relation to Darwin's Conception of Species," Ibis, Vol. 6, 1936, pp.310-321, p.311]" (Larson, E.J., "Evolution's Workshop: God and Science on the Galapágos Islands," Allen Lane: London, 2001, p.240)

suggests that Darwin's finches have passed their prime of diversification and may now be headed for extinction.]

David Pfennig at the University of North Carolina at Chapel Hill agrees that the study has important implications. [Pfenning says on his home page: "I am especially interested in testing whether .... diversification is enhanced by developmental plasticity (polyphenism) ... the tendency for genetically identical organisms to produce alternative phenotypes in response to different environmental stimuli" (my emphasis) so his meaning of "the study has important implications" may not be pro-Darwinian.]

For Pfennig, the study's greatest surprise was "the apparent speed with which the character displacement occurs-within a single year!" [Yes. As pointed out in part #1, this is far to rapid to be the Darwinian natural selection of random micromutations. ]

Usually we think of evolution as being a slow grind, he says. [That's because Darwinian "evolution" is "a slow grind"!]

But, Pfennig added, the study suggests that evolution due to competition between closely related species "paradoxically may often occur so rapidly that we may actually miss the process taking place." [Then if "any change measurable at all over the few years of an ordinary scientific study must be occurring far too rapidly to represent ordinary rates of evolution in the fossil record" and hence is "visibly irrelevant" (see part #2):

"Moreover, and with complete generality-the `paradox of the visibly irrelevant' in my title we may say that any change measurable at all over the few years of an ordinary scientific study must be occurring far too rapidly to represent ordinary rates of evolution in the fossil record. ... if evolution is fast enough to be discerned by our instruments in just a few years ... then such evolution is far too fast to serve as an atom of steady incrementation in a paleontological trend. Thus, if we can measure it at all (in a few years), it is too powerful to be the stuff of life's history. If large-scale evolution proceeded by stacking Trinidad guppy rates end to end, any evolutionary trend would be completed in a geological moment, not over the many million years actually observed." (Gould, S.J., "The Paradox of the Visibly Irrelevant," in "The Lying Stones of Marrakech: Penultimate Reflections in Natural History," [2000], Vintage: London, 2001, reprint, p.344)

this "evolution [that] may often occur so rapidly that we may actually miss the process taking place" is invisibly irrelevant! ]

Stephen E. Jones, BSc (Biol).
`Evolution Quotes Book'