The processes of evolution

[QUOTE]Originally posted by mark24:
There are numerous examples of fish adaptions to terrestrial environments, lungfish being the most quoted. Mudskipper species are able to drag themselves around mudflats, in this case gaseous exchange is provided by gills.
[/B][/QUOTE]Not to mention the snakehead fish in the news in the Washinton DC metro area. This fish can survive for about three days on dry land and can use this to migrate from one body of water to another.------------------
"Chance favors the prepared mind." L. Pasteur
Taz

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Originally posted by Hanno:
However, evolution dictates that this capability is not automatic, but that it must have been develop. Therefore, I wish to concentrate on fishes that does not have this capability. Lets take a fish that cannot survive outside water, and cannot use its fins to move around outside water. Acording to evolution, this is what the precursors of land animals must have been like.

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Yes and no, Hanno you actually came very close to putting your finger on a very important but often ignored point of evolutionary biology. Evolution often occurs by an organism taking advantage of secondary traits, ie gas exchange through a membrane/organ where that is not it's principle function, or the use of feathers for something other than thermoregulation. This occurs in a different manner in biochemical systems as well; proteases which can act in mutliple ways ranging from digestion to clotting, the use of a bacterial defense system in open circulations as a basis for clotting in closed circulations (this one is from the LAL system derived from the horseshoe crab). The ability to breath out of the water likely derived from this form of a start.

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I do not agree with the arguement that it was food that lured them out to land. When a whale beaches itself, only animals that can move on land will come out from the water to feed on it. You do not see fishes (such as sharks) that cannot live above water, struggling out to join the feast.

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How about to escape predators. This is a more likely scenerio, and the reason that it happens less now (it does happen some) is that now there are predators on the land as well who have evolved.

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Science assume that things worked in the past as they work today.

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Um, slight correction here, science assumes that the processes which operated in the past operate today. While it might seem like a small distinction it is quite important to understand the difference between processes and specific events or things that worked then vs things that work now.

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This advantage, however great it might be, cannot change the genetic makeup of animals, because genetics is chemistry, and habitat advantiges is not.

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Again, yes and no. NS does notchange the genetic makeup. it acts as a filter. And a fish with better gas exchange and stronger, stouter fins is more likely to be able to "go where no fish has gone before" ( please imagine Star Trek voice). This fish has a greater chance to live longer and have an increased chance of leaving its genes. As genes are chemistry, think of it as a scrubber, certian genes are scrubbed out but others are not.------------------
"Chance favors the prepared mind." L. Pasteur
Taz