 Wysłany: Sob 13:40, 05 Mar 2011 Temat postu: On the Makaloa Mat LondonJack Publishedaambtf |
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| ngest ears you'll succeed in increasing the average in
later generations. For a while. But if you continue to breed from those with the longest ears there will come a time when the necessary variation is no longer available. They'll all have the 'longest' earsand evolution will grind to a halt. In normal evolution this sort of thing is not a problembecause most environments don't carry on exerting consistent and unswerving pressure in one direction. The 'best' length for any particular bit of an animal will normally not be 'a bit longer than the present averagewhatever the present average may be'. The best length is more likely to be a fixed quantitysay three inches. But sexual selection really can have the embar- rassing property of chasing an ever-driving 'optimum'. F louis vuitton wallets on saleemale fashion really could desire ever longer male earsno matter how long the ears of the current population might already be. So variation really could seriously run out. And yet sexual selection does seem to have worked; we do see absurdly exaggerated male ornaments. We seem to have a paradoxwhich we may call the paradox of the vanishing variation. Lande's solution to the paradox is mutation. There will always be enough mutationhe thinksto fuel sustained selection. Tyilai: nike high heels http://www.cesarstworpg.fora.pl/swiat-fantasy,16/glenandranda,6613.html#16753 |
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