I've read some of the topics in the forum and I've noticed some coments and questions about mutations and smart/dumb organisms.
I have 1 suggestion and some "coments" (?) i'd like to make so we can all think them thought.
suggestion: make the mutation rate be different in mitosis and in meiosis (fecundation); Well it so happens (in real life that) mutations are so much often in meiosis (because of crossing over - the process which makes the "father" and "mother" DNA mix up to create a new cromossome) than in mitosis, this would prety much solve the problem that large (and complex) organisms are very sensitive to mutation. With this change the variation will come from the meiosis and not so much from mitosis. Of course this would mean that every organism should have meiosis to have variation. There are a few things we can do to solve this:
- 1- when a cell divide there could be an option ON/OFF "Meiosis" when ON and "Mitosis" when off (and meioses should be used to create the egg of the organism - basicly the initial cell)
- 2- Nothing, yes nothing. In nature, the most simple organisms divide and complete their life cicle only using mitosis (all bacteria, all archaea, most protists, and even some plants) meiosis is a complex mechanism that only appeared late in evolution (at the same time as sexual reproduction did) and this means: simple organisms reproduce ising mitosis and it's enough, complex organisms use meiosis. Since simple ones divide so much often this will compensate for the low mutation rate. In complex organisms they usually replicate less often (even if slightly) and so the meiosis puts more variability on their genomes.
In college I got the formal knowledge of what most of us most probably think already, which is "Genetic drift". I'll explain:
Well, when in a population we have ex: 60% frequency of 1 gene and 40% of other, we expect them to stay in the same proportion if both are equally advantageous, or if it's a gene that is not important at all. But in not infinite populations (which is the case all the time ) there are random chances that the frequency won't stay the same due to random sampling of organisms, this phenomena is stronger the smaller the population is. An example:
if u can't see the image the link is: https://upload.wikimedia.org/wikipedia/ ... _chart.png
Even when it's a gene that is under selection (a useful gene or a "bad" on) genetic drift also plays a role in it. The smaller the population the bigger the role. Don't underestimate it's power, it happens a lot that genetic drift is bigger then selection. (Every one saw this happening I'm sure, when u have a population with one color and all of a suddent the population changes color, probably it was because of genetic drift, since color doesn't aftect it's ability to reproduce and likely only the color has changed).
So basicly evolution, is not perfect, and not predictable, and it doesn't always goes for better, there is more random then u expect.
I usually separate evolution in 3 steps:
- 1- Mutation (for variability)
- 2- Selection
- 3- Fixation of the gene
So I said all this, please give me your feedback on what u think about all this, if it makes sence, if there are some kind of sollutions to somethings... etc