I'm not a biologist by any means, is there a limit 'Evolution'?

Question

It seems that where living organisms are concerned, anytime changes, especially in the environment occur, they seem to learn to adapt to any situation even to the extreme. For example there are fishes in the Arctic that developed an Anti-freeze protein so they wouldn't freeze in subzero temperatures! That's just one example in a world littered with countless more! What I would like to know is: are there limits to how living things can evolve? If all the animals and plants on land slowly died would we develop flippers? Or suppose oxygen slowly diminishes, would our body learn to metabolize with nitrogen?

Answer 1

There certainly are limits to what evolution can do,
the laws of physics and chemistry, as well as the
past history of each species' evolution set the
limits on what can occur. Horses and pigs and
humans are never going to be able to fly under
their own power. They have taken an evolutionary
path that prevents them from doing so. Primarily
they are too large in most cases. Muscle-powered
flight just doesn't work for anything very heavy, not
enough energy is available.

Environmental change does not always result in
evolution. When the Ice Ages hit the northern
continents what happened was not so much any
change in the species, but a migration of whole
communities first south then back north again as
the climate altered. This was a lot easier than
changing evolutionarily. There was some adaptation, of course, but relatively little either of
extinction or origin of new species.

Major disasters, of course, do not allow time for
evolution to change anything. Although it is not
as slow as is often thought, there is a limit to how
fast it can adapt. There has to be time at least
for production of a few new generations of plants
or animals.

There is a great deal we still do not know about
the capabilities of organisms in relation to the
physical environment. Why, for example, do we
have to have oxygen? Is there no other element
that could act as a receptor for the loose electrons
and protons produced by metabolism? Possibly
not, or something might have developed the
ability to use the other element. So we die more
quickly if deprived of access to oxygen than of any other essential element.

Answer 2

Well, evolution is of course limited by the laws of physics and chemistry. For example, an organism could not evolve the capacity for levitation or telekenesis.

But overall, you are correct. Given enough time, an organism can evolve all sorts of incredible adaptations to help it survive.

However, the evolution of an organism is still at the mercy of its genetic material. It can produce new genetic material, but it cannot do so *at will*. Just because an antifreeze protein would be very useful, doesn't guarantee that such a mutation would appear in time to save the animal from extinction ... it just means that if such a mutation were to appear, it would be very advantageous and propagate rather quickly through the genome of the organism.

"If all the animals and plants on land slowly died would we develop flippers?" Maybe. If we didn't go extinct, then chances are we would evolve some things that help us survive better in water ... but it would not necessarily be flippers ... it might be something better ... or just different. But hey, if seals, dolphins, and whales can evolve from land-dwelling organisms, then why couldn't our descendants do the same

As for learning to respirate nitrogen instead of oxygen ... that is such a fundamental difference in the metabolism of animals that I'm guessing it would take the better part of a billion years. But hey, the entire animal kingdom is the result of a new form of metabolism that developed to breathe oxygen (the early earth had no oxygen in the atmosphere until the plants put it there). So strange things have happened.

Answer 3

I think you answered your own question. For a non-biologist you seem to have a good understanding of evolutionary biology. To answer your question, there is no limit to evolution unless a species is completely wiped out. Say we have a nuclear holocaust and radiation kills lots of folks on earth. It's quite possible that in about 200,000(we only get a useful evolutionary trait on average once in this time span) years that we would genetically develope an adaptation to the radiation. If oxygen indeed diminishes and we have time to adapt, we will do just that. So i guess the only real limit to evolution is time.

Answer 4

Evolution combines two features -- genetic reproduction with recombination and mutation. The first allows combinations of existing trait and the second potentially introduces new traits. Sudden changes with alternate metabolic pathways are improbable during sudden evironmental shifts, and the likely result is extinction. The major limiting factor to evolution is generation time. Only so many changes can happen at once.

Answer 5

Evolution is a process of living things adapting to their environment. Those species that fail to adapt will die. This has happened time and time again over the course of the earths history. While species will try to evolve to meet the environmental situation they don't always succeed.

Answer 6

Evolution is limited by
the amount of variation (genetic differences) already present in a population,
the amount of recombination (sex and mixing of genetic material),
number of offspring (evolution acts on individuals not specific genes),
time (evolutionary pressure vs generation time),
mutation rate (new variation)

Basically, evolution doesn't really have a chance if a very small or homogeneous population experiences a drastic environmental change.

Answer 7

There is almost no limit to evolution, I believe. Before we used oxigen, there were live beings that used other gasses and produced oxigen. There are bacteria that live in pools of boiling water. If changes will be slow, evolution will continue. but evolution is very slow-veeeeery slow. So changes now are a bit to fast for it. But I think that life will not disapear. It will continue to prosper in one way or another.
LP, Jauzi