A main sequence star is bigger than a neutron star,because neutron stars are remnant degenerate matter from a collapsed star,they are completely made out of Neutrons and are extremely dense,and have a diameter of only a several Kilometers.M<span>ost of them have a mass of 1.35-2 Solar masses.</span>
When a mutation has an effect that helps a species adapt to an environment, and specimens of both genders have it, it will end up taking over, causing evolution to gradually happen.
A concentration gradient must exist. hope this helps