Entry #3: Sex Ratios and ESS

The ESS concept stands for Evolutionarily Stable Strategy. Dawkin states that this type of strategy is a strategy that if most members of a population adopt it, cannot be bettered by an alternative strategy. The reason Fisher stated that a sex ratio of 50:50 (males:females) is an ESS is because he said that it will counter any bias. If there was a gene that was bias towards a certain sex, then the others would have lower mating success just as Fisher states. But, selection will go in the other sexes favor, making sure the ratio will stay balanced again. I believe that the autosomal chromosomes and the sex chromosomes will both favor a 50:50 ratio. Both males and females need the autosomes and the sex chromosomes to become a full human being. The autosomes are the first 22 pairs, which both males and females need so there is no competition needed, and the sex chromosomes which is the 23rd pair, is needed in both males and females. The only difference is the sex chromosomes determines the sex of the male or female. The only competition here is whether or not the chromosome will be XY or XX. The cytoplasmic elements are not a 50:50 ratio. Some elements are used more than others, but this cannot be helped since every element has a certain job it must do. Such as the mitochondria which makes ATP, it will not compete with the endoplasmic reticulum because it has no reason to take its job. The chromosomes are different from the cytoplasmic elements in that they determine the make up of a human being and the cytoplasmic elements help to keep them running. Therefore there is no reason for the cytoplasmic elements to counter each other if the ratio is not always 50:50.