IB ESS SL 3.1.4 Natural Selection Questions

natural selection (resulting from changing environment) acts on existing genetic variation (that has arisen through mutations over the eons);
natural selection increases the survival of fittest genetic variations/traits;
these traits are heritable/passed onto offspring / selected individuals will have higher reproduction potential / so species will adapt to different environments;
the proportion of these traits may increase in some populations/in subsequent generations;
which can lead to speciation/increasing species diversity if there is reproductive isolation;