Is there such thing as de-evolution?

[scilover89]

I wonder whether there is such things as de-evolution? In the past, there's an extinct bird called Do Do bird (Is it? I am not quite sure.).At first, it can fly, but several years later, somehow their wings become unable to fly, which made them vulnurable to predator and consequently led to their extinction. Same case also happen to chicken.

 

[iansmith]

There is no such thing as de-evolution. A living organism will adapt to the environment presenteed. Do-Do bird were early type of birds that were not capable of flight like many other birds. Do-do birds are the early species between reptile and birds. They have reptilian like characteristics and bird like characteristics.

 

[alpha_wolf]

To expand on iansmith's reply, a species may evolve a feature such as wings, then as the environment changes (e.g. predators die out), the may no longer need the feature. In that case, the feature is likely to degenerate, because it requires energy to maintain it. Although the feature is now disappearing, this is still a process of "normal" evolution.

 

[nautica]

Ian, Although you are correct "de-evolution" does not exist (not possible due to that fact that evolution only means change reguardless of direction) but maybe we could use this term to describe the now changing human population in industrialized nations.

Allow me to illustrate my point (mainly b/c it is 4:30 am, I can't sleep, and I'm bored) For 1000's of years the human species has been able to survive mainly due to its ability to store fat. Now, in a time of abundance (yes, I know this is not the norm world wide but let's pretend) individuals are becoming increasingly over wieght. They are not neccessarily dying before reproductive age but some studies have shown that that overweight indivuals have fewer offspring than those who are not.

Now with that being said. Let us pretend that things continue the way they are for 1000's of more years (with no genetic manipulation or other catastrophic events). Abunance becomes more and more prevalant world wide and the ability of fat storage begins to decline. Eventually, humans could eat at McDonalds 5 times per day and still be lean. This would be a selective advantage and theoretically skinny people would be the norm while obesity would cease to exist.

After this type of evolution has occurred it would have the ability to wipe out the human population if we were once again were faced with having to be hunter/gatherers in order to survive. This is a circumstance in which I would like for the term "devolution" to be used. It could be defined as:

devolution - A change in allele frequency in which once beneficial traits are no longer beneficial and are selected against.

No, I don't think I like this definition - b/c it does not truly say what I am wanting to say. But, do you see what I am trying to say. Does anybody have a better definition? Or is the lack of sleep over emphasizing my ignorance? :zzz:

Nautica

 

[Moonbear]

Nautica, what you describe is still evolution, even if it's evolution in a direction that reduces variability to the extent that the species becomes extinct. There are quite a few "niche" species that have encountered this problem. Giant pandas being one popular example. They've become so specialized to one type of environment that they no longer have the ability to adapt to any change in that environment.

 

[Phobos]

which made them vulnurable to predator and consequently led to their extinction.

As I understand it, the flightless do-do varieties were doing well in their environment until their ecosystem changed. Specifically, "invasive species" (see below) moved into their islands and the dodos were not equipped to deal with the change in habitat & predator types.

http://www.amnh.org/exhibitions/expeditions/treasure_fossil/Treasures/Dodo/dodo.html?dinos

Some of the birds may have been eaten by the Dutch sailors who discovered them. However, the primary causes of their extinction were the destruction of the forest (which cut off the Dodo's food supply), and the animals that the sailors brought with them, including cats, rats, and pigs, which destroyed Dodo nests.

 

[tribdog]

did you know that one day some guy was cleaning out a museum and came across a stuffed dodo, but it was really dirty so he threw it away and it was the only one in the world. Now we have no stuffed dodos to study.

 

[loseyourname]

Ian, Although you are correct "de-evolution" does not exist (not possible due to that fact that evolution only means change reguardless of direction) but maybe we could use this term to describe the now changing human population in industrialized nations.

Allow me to illustrate my point (mainly b/c it is 4:30 am, I can't sleep, and I'm bored) For 1000's of years the human species has been able to survive mainly due to its ability to store fat. Now, in a time of abundance (yes, I know this is not the norm world wide but let's pretend) individuals are becoming increasingly over wieght. They are not neccessarily dying before reproductive age but some studies have shown that that overweight indivuals have fewer offspring than those who are not.

Now with that being said. Let us pretend that things continue the way they are for 1000's of more years (with no genetic manipulation or other catastrophic events). Abunance becomes more and more prevalant world wide and the ability of fat storage begins to decline. Eventually, humans could eat at McDonalds 5 times per day and still be lean. This would be a selective advantage and theoretically skinny people would be the norm while obesity would cease to exist.

After this type of evolution has occurred it would have the ability to wipe out the human population if we were once again were faced with having to be hunter/gatherers in order to survive. This is a circumstance in which I would like for the term "devolution" to be used. It could be defined as:

devolution - A change in allele frequency in which once beneficial traits are no longer beneficial and are selected against.

No, I don't think I like this definition - b/c it does not truly say what I am wanting to say. But, do you see what I am trying to say. Does anybody have a better definition? Or is the lack of sleep over emphasizing my ignorance? :zzz:

Nautica

De-evolution would have to be the opposite of evolution; that is, a change in allele frequencies that makes a given species less fit to survive in its environmental niche. What you are describing is a beneficial change that becomes detrimental when the environment itself changes in an unfavorable way. It is quite common for the environment to change at a faster rate than a species can adapt, which is why the vast majority of species that have ever existed are now extinct. This is, in fact, a crucial component of evolution, as it ensures that there will always be niches to fill somewhere.