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The standard answer to:

what is evolution?

is:

It is a change in allele frequency over time!

I believe a complete definition should encompass the following concepts:

  • mutations
  • copy number variation (CNV)
  • codon usage
  • chromosome numbers
  • maybe some other things...

My questions are:

  1. Would it be worth it to talk about phenotype in a definition of evolution?
  2. What are the alternative definitions that have been proposed?
  3. What is your definition?

Note: I would rather talk about genetic evolution, but if you think it is worth making one definition for genetic and cultural (and some other stuff maybe) evolution, you're free to suggest it!

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1  
I would call it "heritable change through time or space caused by the mechanism of evolution (selection and drift)" that way it doesn't exclude epigenetic inheritance –  GriffinEvo Nov 9 '13 at 14:20
    
Asking the what our individual definitions are is too subjective. Also, are you looking for a definition? Or an explanation. You mention "worth"... worth to who? –  Articuno Nov 9 '13 at 16:45
    
@Sancho I think a definition is never objective. It is totally arbitrary to decide what is hidden behind the word "evolution". Therefore, I would have expected several suggestions of definition. I guess a good definition is a definition that fits quite well the everybody sense of what is the boarder of a concept. "Worth" to any individual person willing to answer this question. –  Remi.b Nov 9 '13 at 16:54
    
@Sancho Explanation? Explanation of what? I don't think I'm expecting any explanation about the science of evolutionary biology. I guess my question is close to a question of philosophy but I expected better answer by posting here than on philosophy beta. –  Remi.b Nov 9 '13 at 16:54
    
@Remi.b Are there "wrong" answers to this question, then? –  Articuno Nov 9 '13 at 17:01

3 Answers 3

up vote 1 down vote accepted

Theoretical biology spans multiple disciplines and the unaccompanied term evolution is defined differently in each:

As such chemical evolution is different from time evolution in physics and many other systems in theoretical biology that "evolve". These do play a role in theoretical biology.

Also, what standard answer to evolution in the field of theoretical biology are you referring to?

I recall learning that an allele as a special[:species:] gene variant, is defined as such as being present in at least one percent of the population. That definition has broadened meanwhile. A definition that has broadened.

Point in case, I don't believe there to be an evolutionary master-framework to (yet) exist, along the lines of desires for a Theory of Everything in physics.

On the other hand, as soon as you cross the boundaries of biological evolution, like let's say in the most primitive of living, biological entities, you are bound to cross over to cultural evolution as well. ( I am no expert on the subject, there are probably other intermittent steps as well). Synergistic effects in the process of evolution may even be considered in Quorum Sensing's most favorite model: Vibrio fischeri.

A simple search on the subject instantly yielded me:

"Evolution of alkaline phosphatase in marine species of Vibrio". J Bacteriol....

In other words: molecular evolution, as being part of the many evolutiony research focuses.

The idea and gross effects of Darwinian evolution are often rather straightforward at first glance. All the little details, that have to be accounted for -with scientific rigor-, as science itself is evolving, are probably where the team-work starts, as do the discussion.

So the only fixture you can count on is team in science.

The introduction to the evolutionary topic at hand, that you would use in an abstract or introduction would depend on the scientific sub-discipline, and would likely already be readily available through peer-publication.

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It is a change/development of state. You have initial state and some transition function, which specifies what is the next state for the current state. The state evolves or changes in time. Evolving = developing over steps. Here, every step is a state. It is more general than genetics. Control theory, computation engeneers like it also.

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I think that the additional elements that you are suggesting make a lot of sense for a definition of "biological evolution." Even the standard definition that you gave mentions alleles, which are specific to biology. Evolution, however, needn't be biological. It is the result of a combination of general mathematical principles. The same thing can happen in systems that have different mechanisms for allowing it. Calling all of these things evolution is useful, because the same principles apply to all of them, even if the implementations vary. Moreover, a lot of the goal of science is finding the simplest and most generally accurate explanations possible; part of what's so cool about evolution is that it is really simple, conceptually, but has such massive ramifications. Thus, I would suggest the following, even more general, definition (which, incidentally, is the one that I have generally heard described as standard).

Evolution is a change in a population over time. It requires that 
the population exhibit variation in heritable traits and differential 
reproductive success based on these traits.
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