Thanks for the education. I will try to put down a few learnings about mutation and speciation as you have told me. I also use some examples that I could understand better for illustrations.
- A species could mutate a lot, but not becoming a new species. So the rate of mutation is not necessary a timing mechanism for speciation
It has an impact, but in many cases it is not the only factor. However, you can get a new species through mutation alone.
- A species could mutate just a tiny bit, but ended into a new species. These species may look alike, but they do not mix in breeding. A example is horse and donkey. Right?
Yes, and they might be even more similar in appearance. Sometimes it is very difficult for human scientists to identify which species an individual belongs to.
- There are several other factors/processes individually, or combined with mutation to cause speciation. But which one would eventually cause speciation is not known.
Let's be careful here. It is not that the cause of speciation is unknown. It is that sometimes there are multiple causes. But we can still know what they are. It is not a case of having to choose just one of several potential causes as "the" cause. All the factors have an impact.
Perhaps you are thinking of speciation as something that happens at a particular moment. That is not the case. Often populations separate slowly and gradually so there is a long period in which interbreeding still occurs, but on a less and less regular basis.
So we have multiple factors interacting over time, and speciation is a gradual result of all of them acting together. But that is not at all the same thing as saying we don't know the cause(s).
- Genus Homo only had a few species even it has existed for 2-4 m.y. Currently Homo Sapiens is the predominate existing
species in the genus.
Not the predominant existing species. The only existing species. Btw it is not unusual to have only one existing species in a genus.
If the above understandings are correct, then they have the following consequences or implications.
- Even we suspect a few factors of speciation, we do not know which one caused the separation. We do know it happened
afterwards by various methods.
We do more than suspect some factors. We know what factors lead to speciation. Any factor which leads to isolating a population (in any sense) has the potential to lead to reproductive isolation eventually. Reproductive isolation is the indicator of speciation. Mutation and other factors work together to produce reproductive isolation. We know what those factors can be, and study of specific cases can tell us which factors were operative in those cases.
In the island lizards, the factor operating along with mutation was geographic isolation. You will note that on one island there were two populations of the same species each adapted to a different habitat on the island. However, although the adaptation to different environments led to establishing different variants of the species, the lack of isolation prevented speciation.
- When speciation does not take place, we do not know why.
On the contrary, we do know why. We can point to the factors that maintained gene flow and prevented isolation.
- Two species could look very similar. But they do not interbreed. Sometimes the difference could be only detected at the level of DNA sequence
Right. I remember reading of several species of squirrels which scientists could not tell apart even with blood analysis. They only figured out they were different species, because each was infested with a different species of tick and the various tick species could be differentiated.
- Genus Homo is not a very successful one as most of its species were extinct. But the species Sapiens becomes predominant not only over others in the genus, but over other kingdoms.
Well, that is a pretty subjective definition of success. By other criteria the genus is very successful. I don't know what you mean by "predominant ... over other kingdoms" though. Last I looked humans were still animals, not plants or fungi.
- Species Homo Sapiens mutates at a certain rate. But the effect of mutation is not known.
In general the effect is diversity. Often it is possible to determine the effect of a particular mutation. But there are 6 billion base pairs the human diploid genome. That is a lot of ground for molecular biologists to cover.
So there are probably specific mutations that have not even been found yet, and many that have not been studied yet.
But with study we can know the effect of a mutation.
- "Race" among species Sapiens is not due to mutation.
"race" is a sociological construct. In scientific terms the human species has no races.
The above conclusions/implications could be further simplified into one: We do not know what cause speciation.
A false conclusion based on some incorrect inferences.
All the above says "creation" to me.
Perhaps you would like to explain why.
