Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: John Chapman on 09/05/2010 01:42:11
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Dwarfism denotes a mutation whereby a person has disproportionately short limbs. So why do we never see animals with the same mutation?
Do you occasionally get mice who can barely lift their bellies off the ground? Or an albatross that can’t fly because it’s wings are too short? What about a giraffe that’s half as tall as the rest of the herd? Or, since we share 97% of our genome with the great apes, do you ever get midget gorillas?
Come to that, what about an oak tree that never grows more than six feet tall? Or a daddy-long-legs spider (a harvestman) that looks like a conventional spider because it doesn’t have the extremely long legs?
A not very funny joke:
What do you call a dwarf stork? A duck.
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Usually because most genetic variations/mutation will mean non survival in the wild. If you don't survive to reproductive age you cannot pass on the mutations.
FTR there are 'dwarf rabbits' but I am unsure if they are selectively bred.
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Birds descended from dinosaurs, so they became smaller to survive.
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Usually because most genetic variations/mutation will mean non survival in the wild. If you don't survive to reproductive age you cannot pass on the mutations.
FTR there are 'dwarf rabbits' but I am unsure if they are selectively bred.
There are a number of 'dwarf' and 'pygmy' varieties of animal but these are not true dwarfs. Generally these denote breeds or species that are smaller than those we generally think about for that species. My wife breeds African Pigmy Hedgehogs (incredibly cute - I'll post a picture if you like) but these are not dwarfs. They are just a small species and the entire population is a similar size.
So what about domesticated animals that have been removed from the Darwinian 'survival of the fittest' selection process. Do we ever get dwarf cows, for instance. Would these be destroyed by farmers at birth or do they never excist?
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This story
http://www.independent.co.uk/life-style/pets/news/is-this-the-smallest-horse-in-the-world-1956733.html
might be about a dwarf member of a pygmy breed.
In any event, it's a very small horse.
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There are a number of 'dwarf' and 'pygmy' varieties of animal but these are not true dwarfs. Generally these denote breeds or species that are smaller than those we generally think about for that species. My wife breeds African Pigmy Hedgehogs (incredibly cute - I'll post a picture if you like) but these are not dwarfs. They are just a small species and the entire population is a similar size.
fair point.
So what about domesticated animals that have been removed from the Darwinian 'survival of the fittest' selection process. Do we ever get dwarf cows, for instance. Would these be destroyed by farmers at birth or do they never excist?
I went searching for the gene responsible for 'dwarfism' (it's FGR3 "fibroblast growth factor receptor 3")
and then found this to do with cows..
The bovine fibroblast growth factor receptor 3 (FGFR3) gene is not the locus responsible for bovine chondrodysplastic dwarfism in Japanese brown cattle.
http://ghr.nlm.nih.gov/gene=fgfr3 (http://ghr.nlm.nih.gov/gene=fgfr3)
which doesn't link the same gene to dwarfism, but does confirm that it, at least, occurs within the domestic population.