Today, Phys.Org reports on the following research item concerning bird feather evolution:
Research by Cambridge PhD candidate Thanh-Lan Gluckman, published today in the Biological Journal of the Linnean Society, looks afresh at similarities and differences in plumage in almost 300 members of the Anseriformes and Galiformes orders . . . /blockquote>
It seems that the idea that sexual selection determines this kind of plumage dates well before the time of Darwin (Charles, that is, since his grandfather, Erasmus, was very big on evolution, and very big on sexual selection as a conduit of said evolution.)
The Phys.Org articles tells us:
As early as 1780, the Philosophical Transactions of the Royal Society of London published a paper by John Hunter proposing that plumage differences between the sexes were driven by sexual selection. Ever since, the prevailing view of sexual dimorphism has been one of showy males strutting their stuff to win over demure females. The predominant explanation put forward to explain how differences in dimorphism evolved hinges on mating habits; males of polygamous species (those with more than one mate) had developed spectacular plumage in order to attract a maximum number of females, while monogamous species (those with one mate) retained similar plumage.
But Thanh-Lan Gluckman discovered something very different: males and females seem to show the same propensity for developing plumage of any pattern. The prevailing idea was that males and females of bird species shared common genes for the bright plumage and varied patterns, and that “male” plumage resulted from a loss of some of these common genes by the females:
Since the 1980s, differences in the appearances of male and female birds have been seen through a prism of genetic correlation. In other words, it was thought that female birds may have evolved similar patterning to males due to common genes but that female patterns would be subsequently lost as it is not beneficial.
But, alas, this didn’t turn out to be the case. Can you imagine that: a Darwinian understanding/prediction (back in the 80’s they didn’t have the tools to investigate the genome as we do; but they did ‘presume’ = ‘predict’, common genes) gone wrong?!!??! Say it isn’t so!!
So, Gluckman tells us:
“My research looked at the plumage patterns of male and female birds on a separate and equal basis – and then went on to identify similarities and differences between them. By tracing the evolutionary pathways in the dimorphism of 288 species of waterfowl and gamebirds, I reconstructed the evolutionary history of plumage pattern sexual dimorphism, which allowed me to demonstrate that plumage patterns in females are not a result of genetic correlation. . . .
. . . Essentially, what I found was that plumage patterning is remarkably labile – both male and female birds have the capacity to change between different types of patterns.
And, so, what do we end up with? Adaptation; NOT evolution. Alas, the poor Darwinians. Wrong again.
Gluckman tells us:
In expanding the definition of sexual dimorphism, and reconstructing evolutionary history, I found that . . . the plumage patterns of birds seem to transition easily between different types of dimorphism, which is congruent with adaptation to fluctuating social and environmental conditions.
Another day; another bad day for Darwinism! The beat goes on . . . . . . .