It doesn't per se. Speciation occurs usually when two gene pools are isolated long enough by geography or by separate selective pressures that one group becomes able to reproduce with the other with difficulty, and eventually not at all. Horses can mate with zebras and a few other animals for instance, but produce sterile offspring.
Speciation has been observed in nature many times, and forced to occur in the laboratory. Google "instances of speciation" for examples.
natural selection and common descent
Charles Darwin! ummm it's kinda obvious! Durr
explain the correlation between Darwin's theory and Malthus' idea
If there is not reproductive fitness conveyed by a variant trait, then natural selection has nothing to select and nothing to promote into the populational gene pool.
He explained them in terms of descent with modification, common descent and natural selection.
nothing
bears light and dark
genes
How it can change in response to its enviroment
Yes, it is true.
To attract females. Natural Selection*
eszter likes boys <3
Specialization
According to science, natural selection chooses the best features for the best survival. When those processes do not occur for some reason, the species does not survive.
please answer
natural selection and common descent
Artificial selection is anthropogenic -- humans interfere with nature to determine what traits get passed on, whereas natural selection is when through sexual reproduction the traits passed on are determined by survival of the fittest.