More about how evolution works; stasis (Evolution)

by dhw, Wednesday, October 14, 2015, 12:22 (3326 days ago) @ David Turell

DAVID: Many species remain the same for hundreds of millions of years. We do know complex organisms become more complex, but stasis and punctuated equilibrium are present also:-http://www.evolutionnews.org/2015/10/stasis_when_lif100011.html-QUOTE: "An evolutionary biologist at the University of Oslo, Kjetil Lysne Voje, offers an explanation for stasis:
The most wide-spread explanation is stabilising selection. It suggests that the advantage for a species which is already well adapted to its environment will be to avoid changing much. [...] 'Stabilising selection is a very good explanation for stasis, as it helps a species remain unchanged. But it has some problems, as it is hard to conceive of an optimal form that would not change in the course of millions of years," says Voje."-This is hardly an explanation of stasis: it merely tells us that stasis occurs because it enables things to stay the same. We call it stasis BECAUSE things stay the same! Why would an “optimal form” change? It may need to adapt (bacteria are a prime example), but that's all. The mystery is not stasis but innovation, and this might well happen if there are changes in the environment that allow for improvement. That doesn't mean innovations will always happen when the environment changes, and why should we expect it to? Each innovation has to take place within individual organisms, and that will require exceptional individuals. Once the “invention” works, it establishes itself, and if it's optimal, it won't change (= stasis).
 
DAVID: Comment. Voje is struggling for an answer that sounds real. We know the Earth has had enormous changes as evidenced by hot periods ( palms in the Arctic), glacial periods, and continental drift, and so many species show no change. they arrive full-blown and disappear millions of years later looking the same, or are still here laughing at us because we do not understand the process of evolution.
-“...and so many species show no change” is not really logical: if the environment changes, you would expect species to change, and in many cases they do - the biggest change being that they die! Others, however, adapt. The mystery is why new species arrive. See above.