An allele is a possible variation of a gene. For example, if “height” were a gene, “tall” or “short” would be alleles of the gene. (Of course, genetic information carries much, much more detail and cannot be so succintly described. In reality, the observed phenotype of an individual’s height is the result of many interacting genes.) Genes and their variants – alleles – are not fixed. Interesting patterns emerge when looking at the distribution of alleles in a population. When you look at the change in this distribution between generations, you’re studying allele flow. Read more

Natural selection conveniently describes how individual traits become more or less common in a population. As such, natural selection is statistical, as we’re primarily interested in the population moreso than individuals within the population. Two things need to be present for natural selection to take place. First, there must be genetic variation within a population. Second, there must be inheritance of genes between generations. Read more

When we talk about a “possible variation”, “distribution”, “random drift”, this should tip us off to the usefulness of statsitical models in describing biological population. The mathematics we can use here are extremely useful, amazingly so in many cases. But we need to take caution against treating the model as if it were reality. Many of us are tempted to seek completeness in mathematical modeling, either through formal precision or computational power. Read more