Leucistic Blue Duck near Chateau, Tongariro National Park

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Uncia

Re: Leucistic Blue Duck near Chateau, Tongariro National Par

Postby Uncia » Fri Oct 17, 2014 8:13 am

I don't know if you are serious as you answered your own question.

"Natural selection results, over the course of generations, in beneficial (or "fit") features replacing their disadvantageous counterparts. Thus, natural selection causes beneficial features to become increasingly more common with each generation, while the disadvantageous features become increasingly rare."

This MAY or MAY NOT be advantageous, that's when natural selection will take its course. Also I would note, that he has found a mate, so he can't be to undesirable :D
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zarkov
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Re: Leucistic Blue Duck near Chateau, Tongariro National Par

Postby zarkov » Fri Oct 17, 2014 8:33 am

I thought my link referred to the opposite effect.

However, he's the one doing the tail feather tugging, not the other way around, so time will tell.
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Neil Fitzgerald
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Re: Leucistic Blue Duck near Chateau, Tongariro National Par

Postby Neil Fitzgerald » Tue Apr 28, 2015 7:38 am

He was still present with his mate on the 29th of March.

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RussCannings
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Re: Leucistic Blue Duck near Chateau, Tongariro National Par

Postby RussCannings » Tue Apr 28, 2015 9:35 am

Leucism is a recessive gene so can only produce similar offspring if his mate is leucistic as well. It appears that will not happen and we'll be back to regular Blue Ducks across the board. It would seem unlikely that tan-coloured Whio would have any advantage as their camouflage would be compromised. Ultimately its up to the lady ducks and feral cats to decide.
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mark ayre
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Re: Leucistic Blue Duck near Chateau, Tongariro National Par

Postby mark ayre » Wed Apr 29, 2015 1:05 pm

That is exactly where i saw them last year under that first bridge as you drive up the road to Chateau.
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Re: Leucistic Blue Duck near Chateau, Tongariro National Park

Postby Ian Southey » Tue Nov 08, 2016 7:34 am

I saw this pale bird on October 25th by the bridge below the Chateau so still going strong. Miserable grey wet day so no pictures.

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Re: Leucistic Blue Duck near Chateau, Tongariro National Park

Postby Ian Southey » Sun Nov 26, 2017 9:51 pm

Still present in the same place with a mate and 5 downy ducklings on the 22nd.

Ian
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Re: Leucistic Blue Duck near Chateau, Tongariro National Park

Postby mark ayre » Sat Dec 02, 2017 7:14 am

This pair are still down the below the Chateau with 4 young this year.
Good to see them hanging on in there.
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Boris
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Re: Leucistic Blue Duck near Chateau, Tongariro National Park

Postby Boris » Thu Dec 14, 2017 6:01 pm

Yes I agree with Zarkov here. Leucism is caused by a broken gene or genes, and is the result of a loss of genetic information. It is not an example of evolution, rather of devolution or genetic entropy. Fortunately, broken genes are recessive by definition, so only expressed in the double recessive animals. Whenever paired with a working gene in heterozygous critters, the normal phenotype has to be expressed.

I marvel that birds retain their colour and pattern over time, as it doesn't seem to affect survivability or mate selection all that much, judging by the numbers of leucistic birds around. I have always questioned the evolution paradigm here. Things seem to be slowly winding down rather than winding up.
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David Riddell
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Re: Leucistic Blue Duck near Chateau, Tongariro National Park

Postby David Riddell » Fri Dec 15, 2017 9:05 am

Boris wrote:Leucism is caused by a broken gene or genes, and is the result of a loss of genetic information. It is not an example of evolution, rather of devolution or genetic entropy.

Evolution doesn't have any preferred direction, and human notions of progress are largely irrelevant - sometimes things evolve towards greater complexity, and sometimes the other way. But point mutations in genes giving rise to effects like leucism are not a major part of the evolutionary process, at least not in complex multicellular organisms (things are rather different in microbes), although presumably all-white species such as egrets first arose in this way from coloured ancestors. There are other exceptions, such as the evolution of colour vision in primates (https://sites.oxy.edu/clint/physio/arti ... vision.pdf), although that required a duplication of an entire gene as well as point mutations. Events such as this are rare though - much more important in macroevolutionary change are mutations in the switches which affect gene expression during development (http://www.pbs.org/wgbh/nova/body/gene-switches.html). These are what give rise to changes in size, body proportions, details of colour patterns and many other effects.

I marvel that birds retain their colour and pattern over time, as it doesn't seem to affect survivability or mate selection all that much, judging by the numbers of leucistic birds around. I have always questioned the evolution paradigm here. Things seem to be slowly winding down rather than winding up.

I would've said that leucistic birds are actually pretty rare. They tend to be harassed by their congeners, and are often more conspicuous to predators. With a few exceptions such as this duck, birds with unusual plumages are generally less successful at attracting mates. It could be that this is less important in ducks, given the number of feral domestic types living apparently successful lives in the wild, and the degree of hybridisation between closely related species, but for many if not most birds colour and pattern absolutely play an important role in mate selection. For an extreme illustration see https://www.scribd.com/document/3538800 ... ale-Choice

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