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Surely there is always selective pressure ? Why wouldn't there be ?
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So essentially substantial mutation would only occur when something's design is a liability ? IE: Just noise ? I see what you are saying , well kindof , but that doesn't seem to be in line with forinstance the general argument of avian evolution . The general argument I've heard was that a cat/snake whatever developes a mutation which provides it with a 'slight' benefit EG: Falls to the ground slower (like 2 %) than another organism of the same species. Surely the old species that fall slightly faster is not a liablility but a fatality and should be 'unnatural death'.
Basically what I'm hearing is that organisms would only mutate when required ?
Selection pressure and mutation always exist. However, if an organism is well adapted to its environment, any chnage is likely to be detrimental, and thus will be selected out. The selection pressure is for stability. If the environment changes in any way and the organism's adaption becomes sub-optimal, changes will be more likely to be favourable and thus be selected.
Alway remember that evolution is a combination of two factors:
random changes (mutation) mediated by a
non-random filter (natural selection).
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