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.
bears light and dark
How it can change in response to its enviroment
Yes, it is true.
To attract females. Natural Selection*
please answer
natural selection and common descent
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.
Specialization
No, there are no other theories but the theory of evolution by natural selection that explain so much about evolution.
Darwin used the theory of natural selection to explain evolution. Natural selection is the process by which organisms best adapted to their environment tend to survive and pass on their genetic traits to offspring. This concept helps to explain how species gradually change over time, leading to the diversity of life we see today.
Its NaTuRaL sElEcTiOn if you didn't know.
Charles Darwin! ummm it's kinda obvious! Durr