So I am taking an introductory Biology Course and I was recently introduced to the idea of Hardy Weinberg Equilibrium. I wanted to find out why exactly we calculate the frequencies of alleles in the next population using the law of multiplication.
In a hypothetical population of let's say 300 civets, 20% of the gene pool codes for blue eye color and the remaining 80% codes for black eye color. It is given that blue eye color is recessive.
300 civets = 600 alleles total
80% code for black eye color = 480 alleles
20% code for blue eye color = 120 alleles
When we calculate the frequencies of the next population we basically say what is the probability a given offspring will this pair of alleles. Following the example above, I would argue that the probability an offspring has two blue eye color alleles is (120/600) * (119/600). However, my textbook says that it is (120/600) * (120/600) = 0.04 but doesn't that assume replacement of alleles! My only rationale is that as the population tends towards infinity the difference becomes negligible.
Am I right?