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Author Topic:   What mutations are needed for a particular trait (e.g. wings) to arise?
NosyNed
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Posts: 8868
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Message 50 of 111 (345518)
08-31-2006 7:04 PM
Reply to: Message 49 by crashfrog
08-31-2006 6:48 PM


insect rarity
From the first site that popped up on that google:

quote:
Unlike the trilobite that has left a prodigious fossil record, the preservation of insects in sedimentary matrix is relatively rare, and essentially limited to the Laggerstat sites. The reason for the scarcity of insect fossil is the poor preservation potential of the insect's exoskeleton.

In addition,I believe the first request was for the evolution of flight in insects which would be as SF guessed very hard to catch in a set of fossils that are scarce to begin with.


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Replies to this message:
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NosyNed
Member
Posts: 8868
From: Canada
Joined: 04-04-2003
Member Rating: 7.2


Message 51 of 111 (345523)
08-31-2006 7:23 PM
Reply to: Message 49 by crashfrog
08-31-2006 6:48 PM


Some insect evolution of flight info
Insect flight evolved about 330 million years ago. There is genetic evidence that wings evolved from articulated gill plates on the limbs of aquatic ancestors, rather than being novel outgrowths from the body wall (Carroll, Weatherbee, and Langeland, 1995; Averof and Cohen, 1997

From: http://www.nurseminerva.co.uk/adapt/evolutio.htm

and from this site: http://www.sciam.com/article.cfm?articleID=0007973F-A85D-102A-A85D83414B7F0103

We see that indeed the evolution of insect flight is NOT well documented in the fossil record as one would expect.

quote:
The oldest known evidence of winged insects�that is, complete fossilized bodies with fully formed wings attached--dates to around 330 million years ago. But because there is a diversity of species capable of powered flight from this time period, insects clearly evolved wings well before that time. "This chert provides a tantalizing scrap of evidence to suggest that we�re missing a huge amount," Grimaldi remarks, "and there�s probably this wonderful progression of insects with protowings yet to be discovered." --Sarah Graham

from: http://www-geology.ucdavis.edu/~cowen/HistoryofLife/CH13.html

quote:
A new cladistic analysis of living stoneflies, based on molecular evidence as well as wing structure and flight style, shows that the most "basal" of living stoneflies are surface skimmers. This suggests, though it can't prove, the stonefly flight began with skimming. The implication, of course, is that the same might apply to all insect flight. Reference: Thomas, M. A., et al. 2000. Molecular phylogenetic analysis of evolutionary trends in stonefly wing structure and locomotor behavior. Proceedings of the National Academy of Sciences, published online before print November 14, 2000.

That site also has a link to videos of skimming stoneflies. I am often surprised by the number of cases where we have living forms which are so very "transitional" in nature.


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NosyNed
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Posts: 8868
From: Canada
Joined: 04-04-2003
Member Rating: 7.2


Message 54 of 111 (345538)
08-31-2006 8:12 PM
Reply to: Message 52 by crashfrog
08-31-2006 7:44 PM


being wrong
Even mine too. She wasn't very good at accepting that she was wrong because she got so very little practice at it.

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NosyNed
Member
Posts: 8868
From: Canada
Joined: 04-04-2003
Member Rating: 7.2


Message 66 of 111 (346164)
09-03-2006 2:20 AM
Reply to: Message 63 by crashfrog
09-02-2006 1:36 PM


beneficial, neutral or harmful
Actually I read a year or so ago that at least some of the antibiotic resistant mutations are somewhat detrimental (in a competitive sense) to the bacteria carrying them. Makes a bit of sense. A baceria doesn't have a hell of a lot of genome to throw around.

The article suggested that we rotate antibiotics. If you remove one for a few years the non-resistant forms out compete the resistant ones and you "get back" the effectiveness of the antibiotic for another rotation.


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