Genotypic variation in at the heart of evolution. The(cid:396)e a(cid:396)e a lot of (cid:272)ha(cid:374)ges happe(cid:374)i(cid:374)g, (cid:271)ut u(cid:374)less that (cid:272)ha(cid:374)ge i(cid:374) o(cid:374) the ge(cid:374)e it does(cid:374)"t (cid:373)atte(cid:396). The change has to happen in the gamete that will become sperm and egg for the change to become heritable. The variance at the population level can be assed two different ways depending on the type of trait. Quantitative going out measuring, actual numbers. Qualitative traits you could do this by looking at a phenotype. We can see evolution happen from one generation to the next. Evolution can be measured by changes in the frequencies over time. Genotypic frequencies represent how the cr and cw are distributed among individuals in a population. They independently came up with the some notion. First thing you need to do figure what the null model is (when nothing is happening. ) Than you compare what is maybe happening to the bas line scenario.