Do Birds of a Feather Demonstrate Parallel Evolution?
A puzzling phenomenon emerges from evolutionary considerations of bird plumage coloration and patterning. Hopi E. Hoekstra and Trevor Price describe the problem in the March 19 issue of Science1 and provide examples:
The pages of any bird guide reveal a spectacular diversity of colors and color patterns. Although color patterns vary within species, often they also distinguish closely related species. Variations in color are thought to have evolved through the interplay of sexual selection and natural selection. What is less obvious–because the birds are on different pages of the guide–is the repeated appearance of similar color patterns among distantly related species (parallel evolution). A list of 9672 of the world’s bird species includes a black-capped chickadee, a black-capped pygmy tyrant, and a black-capped kingfisher as well as 26 other species whose most conspicuous feature–at least prominent enough to prefix their common name–is a black cap. There are 41 black-throated species (in 40 different genera), 8 that are blue-capped, 9 that are orange-breasted, and 29 that are red-billed. There are many such examples of parallel evolution in birds , but the molecular underpinnings of similar plumage patterns among distantly related or unrelated species are still not clear.
Hoekstra and Price take encouragement from a study published in the same issue of Science by Mundy et al.2 The team identified a single mutation present in two unrelated birds that affects the degree of melanism (dark coloration) in their plumage. This can only be a partial solution, however, because they point out that “More than 100 genes that affect the amount and distribution of melanin in the pelts of laboratory mice have been identified; presumably a similar diversity of genes influences melanin production in birds.” However, they take heart that a single amino acid mutation in the one gene studied correlated perfectly with the color variation in the two species: one an Arctic skua, the other a snow goose. They conclude that “The repeated implication of this same gene suggests that there may be a more limited number of genetic mechanisms to produce dark plumage in natural populations than is suggested by genetic studies of lab mice” at least in this case.
An illustration Hoekstra and Price included shows another remarkable example of parallel evolution among orioles. Two nearly identical species are more distantly related, according to molecular phylogeny, than dissimilar ones. It’s as if we were shown two pairs of identical twins, Moe and Joe, and Cindy and Mindy, and told that Joe is more closely related to Cindy, and Moe to Mindy, than the other way around. “Within the oriole group, there are many such examples of similar plumage patterns among different species due to parallel evolution ,” the caption reads.
The authors are hopeful that the work of Mundy et al. will lead to solutions to these puzzles. “Field studies of selection, coupled with characterization of the melanin pathways in each species, will eventually enable a closer tracing of the roles of selection and mutation in generating the similarities and differences between the species,” they say. “Further down the road, we should be able to dissect the genetic basis of more complicated color patterns like those of the orioles.”
1Hopi E. Hoekstra and Trevor Price, “Parallel Evolution Is in the Genes,” Science Vol 303, Issue 5665, 1779-1781 , 19 March 2004, DOI: 10.1126/science.1096413.
2Mundy et al., “Conserved Genetic Basis of a Quantitative Plumage Trait Involved in Mate Choice,” Science 03/19/2004, 2004 303: 1870-1873.
The Natural Law of the Medes and the Persians in their model is evolution, even when it contradicts other laws. Evolutionists cling to their mythical phylogenetic trees like astrologers to horoscopes, but the data suggest a different paradigm: a sharing and sorting of information among different species, leading to traits like black caps, wing stripes, crests, speckles, throat patches, iridescence (see photonic crystals, 01/29/2003) and much more – traits that look designed. The observations do not support a common ancestry cosmology, tweaked with epicycles like “convergent evolution” and “parallel evolution”. When you see common design, why not postulate a common designer?
The authors freely admit that just to get dark color requires a complex set of molecular machines:
The melanocortin-1 receptor (MC1R) resides in the membrane of specialized cells known as melanocytes, which are the site of melanin synthesis in birds and mammals. Circulating melanocyte-stimulating hormone (MSH) binds to MC1R, turning on the cell’s melanin-making machinery.
Are we being asked to believe that up to a hundred molecular machines that control just the melanin pigment all evolved in parallel to produce nearly identical species? What about the hundreds of other genes that produce throat patches, wing bars, and other plumage patterns and colors? Visualize the exquisite patterns on a peacock, bird of paradise, crane, red-winged blackbird, parrot, ostrich, ruby-throated hummingbird, bald eagle, emperor penguin, magpie, rooster or the songbird in your back yard. These patterns don’t just happen; they all require genetic information. This information is transmitted reliably, with only rare slight variations, for many generations.
Mundy et al. are confident that they have identified a “rare example where the major molecular genetic determinant of a quantitative trait has been identified in wild populations,” and that their work on snow geese and Arctic skuas provides “strong support for the notion that, at least in the case of melanism in birds, evolution is driven by mutation rather than selection on existing standing genetic variation.” Nevertheless, to make their story work, they have to wave three hands: “This presumably reflects some combination of a high mutability to functionally novel MC1R alleles, a relative absence of deleterious pleiotropic effects of these alleles, and the visibility of dominant or codominant melanic MC1R alleles to natural selection.” OK, if you want to call that science, let’s put some quantitative numbers in the equation and test it, instead of bluffing about “some combination” of multiple unknowns. On top of all their other contradictions, they expect us to swallow their line about “a conserved mechanism of plumage color evolution through many tens of millions of years of avian history,” after they just told us the gene they studied must have been highly mutable!
The phylogenetic explanation clearly has serious problems, and this one hyped correlation is trivial. Even if these evolutionists could establish that orioles diverged from a common ancestor, they are still orioles: still able to fly, eat, lay eggs, and do all the things birds are so good at, whether or not their feather colors are a little darker in one population than another. Sorting of existing traits has nothing to do with Darwinian evolution in the sense of producing new genetic information. Something has sorted and distributed pre-existing complex specified information in bird feathers, creating beautiful patterns and colorful artwork. That something could be intelligent design. “Parallel evolution” is just a hand-waving term to describe an observation, not explain it.