于 2009 年 2 月 12 日启动,以纪念他诞辰 200 周年
这 一个想法的萌芽
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达尔文的鸽子
1859-2009-达尔文《物种起源》发表 150 周年
Silky Plumage article pictures By Hein Van Grouw
Silky plumage in pigeons; some people love it while others detest it. Whatever you think about it, fact is that this feather mutation survived for ages in the pigeon fancy and is recognised as a permitted feather variety in the Fantail in most countries. Unknown, unloved. So for that reason some facts are given here about Silky pigeons.
The first records
The silky condition, also referred to by Fantail breeders as “lace”, has existed for centuries, and many writers have discussed it. The first one was Aldrovandi. In his Ornithologia (1599) he described the ‘Silky hair pigeon’ as being an unusual appearance and according to him these pigeons came from the Netherlands. He called them Columba pennis crispis (from the Latin word crispus = curled). These were normal shaped pigeons, and they only occurred in white.
Probably the first picture and description of a silky Fantail was by John Moore in his Columbarium (1735).
Linneaus also described and named the Silky pigeon in the 10th edition of his Systema Naturea (1758). He called it Columba hispida (from the Latin word hispidus = rough, hairy). Just like the ones Aldrovandi described Linneaus’ doves were normal shaped pigeons with silky feathers. He thought they came from Africa.
In impersonation of Aldrovandi Brisson (1760) also mentioned the Silky pigeon and he called it Columba crispa.
In the book A treatise on Domestic Pigeons (1765), by an anonymous writer, a white silky pigeon, Runt-like in type with a crest, is portrayed and described.
In the 12th edition of Systema Naturea (1766) the Silky pigeon is still called Columba hispida, although Linneaus now referred to Aldrovandi’s crispis as being the same ‘species’. Linnaeus now thought hispida came from India.
Most of these writers described ‘the pigeon with the hairy feathers’ as being an original form (species). It is obvious that they didn’t know that these pigeons actually were varieties, because mutations, inheritance and genetics were unknown phenomena’s in those days.
Charles Darwin (1868) was familiar with silky plumage in pigeons as well, and he knew it was a variety although he didn’t know anything about the inheritance of this character.
The inheritance
D.G. Steele did the first attempt to unravel the inheritance of silky plumage in the pigeon (1925). He made a study of breeding records obtained from a breeder of white silky Fantails, in Toledo, Ohio. According to these records silkiness seemed to be sex-linked and recessive to normal and he proposed the symbol l (for lace). Steele himself made no breeding tests, what turned out to be a shame.
Later breeding tests, started in 1927 by Cole and Hollander, at the University of Wisconsin, disagreed; the character was neither sex-linked nor recessive. Cole and Hollander’s data, presented in 1939 in the Journal of heredity, showed that silky plumage depends upon a single factor, dominant to normal, and not sex-linked. The symbol l proposed by Steele was altered to L.
In Silky pigeons two types of silkiness can be distinguished. The moderate grade is the heterozygous form, and the extreme grade is apparently the homozygote.
Moderate silkies in crosses with normals give both moderate silky and normal offspring (ratio 1:1). In matings of moderate silkies together both normals, moderate silkies and extreme silkies will be obtained (ratio 1:2:1). So the silkies of the extreme type appear only among offspring of moderate silky together.
Extreme silky mated with normal at last, will give moderate silky offspring only.
Structure of silky feathers
It is readily apparent that silky feathers fail to web normally. The trait seems to be the same as silkiness in silky fowl, but a study of the structural basis of the pigeon feathers shows different. Unlike the condition in the case of the silky fowl, the barbules of the pigeon feather do not lack hooks. General weakness, fragility, and frequent disarray of the barbules, and a tendency of the barbs to twist is the only definite abnormality. And the barbules are not only weak, but their elasticity is very poor as well, especially in the extreme silky.
Silky pigeons can not fly because of their feather condition, although the normal silkies can reach perches or nest boxes of a few feet high. The plumage does not cause any insulation problems and silky pigeons are not more sensitive for the coldness than normal feathered birds. However, they become easily water-soaked and for that reason it is unwise to keep them in an unsheltered aviary.
Silky squabs may often be recognized before the feathers emerge, as the nestling down tends to curl. Here again the extreme silkies show more obvious effect of the gene.
Breeds
In the past a normal shaped pigeon with silky plumage was recognized as being a proper breed and it was called the Hair pigeon or Silky hair pigeon. They were in white only and they existed mainly in Spain and the Netherlands around 1900. The breed is extinct now.
Nowadays the Fantail is the only breed in which the silky type has attained sufficient popularity to become a variety.
One of the reasons Silky is not common in the pigeon fancy is because silky birds can not fly. And perhaps silky might be vexing to some fanciers because the desired feather texture, intermediate, does not breed true. And the homozygotes are too ragged most of the time to show. On the other hand, the heterozygous nature of ordinary silky can just as well be considered advantageous, since a single specimen can produce many more without any inbreeding, from matings with normals. For that reason it is ever so easy to bring the silky trait over from one breed to another to create this feather variety in any other breed. Silky Jacobins and silky Rumanian bare neck tumblers for example have seen the light already.
And is it perhaps a challenge to recreate the former Silky hair pigeon, Columba pennis crispis/Columba hispida?
Hein van Grouw
Aylesbury