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Answer 1
If you have group of a species with dark skin and another group with light skin in an environment with much direct sunlight, the dark skinned gene group will be selected as the dark skin (with more melanin) is protective in that sunlit environment. If the environment is northern, the lighter skin gene will become more common. This variation will be a help in natural selection.
Answer 2
Genetic variation, or reproductive variation, are the mechanisms that cause one sibling to be slightly different from another. It is this difference that allows natural selection to work, for there may be various reasons, to do with these differences, why one sibling is more successful in producing offspring than the other.
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Is natural selection the only force that drives biological evolution?
No. Natural selection requires reproductive variation to work on. Besides reproductive variation and natural selection, there are various forces, biochemical as well as population dynamical, that affect the allelic composition of a population.
How does variation work to help cause evolution?
You have to have variation in order to be able to have more successful variations, which succeed in evolutionary terms, and less successful variations which fail. If there were no variation in a species, there would be no natural selection.
Why was variation the weakest concept in Darwin's theory?
Variation?!?! That was an obvious observation of naturalists that opposed Darwin's concepts totally. Unless you mean the heritability that leads to variation? Explaining that variation was the problem. Creationists of the time explained this by positing god's whimsy in designing his species, but this was shown to be nonsense as natural processes are at work in variation and this can be shown experimentally. The concept of natural selection explained how that natural variation was selected on beneficial traits. What Darwin did not understand is how that variation was passed on to progeny. His explanation was wrong.
What was Charles Darwin's theory on the driving force of evolution called?
Darwin claimed it was the process of natural selection that drove evolution. However this is incomplete, without both a process that creates variation and the process of natural selection evolution could not work. There are many processes that create variation (e.g. mutation, crossover, transformation, infection, conjugation, polyploidy).
What would most likely decrease the genetic variation in the human population?
A widespread disaster would reduce the variety within the human genetic pool by eliminating all but certain segments of the population. A global plague could potentially have the greatest effect, as plagues (see: black plague, Spanish influenza) often will often decimate all of a local population save for those with genetic immunity--thus standardizing that mutation in future populations. Global catastrophe could also inhibit travel, and would limit human reproduction to their immediate region, limiting the genetic range of potential offspring.
What comes first mutation or natural selection?
Natural selection can only work on genetic variation that already exists. So mutation comes first, then natural selection.
Why is variation important for natural selection and what are the main sources of this variation?
Without variation natural selection would have nothing to select from that would confer survivability and reproductive success. on the organisms being selected against the organisms conspecifics and the immediate environment. Mutation and sexual recombination provide the main sources of this variation that is needed to make selection work. Mutation is the variation presented that causes the real adaptive change that can lead to speciation.
Does natural selection work on preexisting variation in a population?
Yes, natural selection acts on preexisting genetic variation within a population. Individuals with traits that give them a survival or reproductive advantage are more likely to pass on their genes to the next generation, leading to an increase in the frequency of those advantageous genes in the population over time.
Does natural selection work on a variation already present in a population?
Yes.
Is natural selection the only force that drives biological evolution?
No. Natural selection requires reproductive variation to work on. Besides reproductive variation and natural selection, there are various forces, biochemical as well as population dynamical, that affect the allelic composition of a population.
How does variation work to help cause evolution?
You have to have variation in order to be able to have more successful variations, which succeed in evolutionary terms, and less successful variations which fail. If there were no variation in a species, there would be no natural selection.
How does genetic variation and environmental factors work together to cause natural selection?
Higher the genetic variation, better luck to deal with wider range of environmental factors hence better luck to pass the sieve of natural selection. ALSO Organisms (plants, animals, bacteria, etc) that have more traits that are favorable in the environment will live longer and have more opportunities to reproduce and create offspring that share their favorable traits. Organisms with traits unsuitable for the environment will die sooner, and will produce fewer or no offspring. If given enough time in a stable environment, the population will eventually reflect the genes best suited for it, assuming pure natural selection.
How do variation and natural selection work together to cause evolution?
They help each other by gradually accumulate in a species, while unfavorable ones may disappear. Over a long time, natural selection can lead to changes.
Why was variation the weakest concept in Darwin's theory?
Variation?!?! That was an obvious observation of naturalists that opposed Darwin's concepts totally. Unless you mean the heritability that leads to variation? Explaining that variation was the problem. Creationists of the time explained this by positing god's whimsy in designing his species, but this was shown to be nonsense as natural processes are at work in variation and this can be shown experimentally. The concept of natural selection explained how that natural variation was selected on beneficial traits. What Darwin did not understand is how that variation was passed on to progeny. His explanation was wrong.
What two limits to evolution by natural selection?
Natural selection is limited by the ability of the population to produce variation. This in turn is limited by the amount of mutation a lineage can survive. Too many mutations, and the effect becomes detrimental. Too few, and the population may not be able to adapt fast enough to changing circumstances and go extinct.
What was Charles Darwin's theory on the driving force of evolution called?
Darwin claimed it was the process of natural selection that drove evolution. However this is incomplete, without both a process that creates variation and the process of natural selection evolution could not work. There are many processes that create variation (e.g. mutation, crossover, transformation, infection, conjugation, polyploidy).
What are three gradual process that change species overtime?
Natural selection, gene flow and genetic drift, though drift can work rather quickly.
