Advantageous to break up genotypes because of continually increasing diversity among interacting species. Advantageous to break up genotypes because of diversity in environment. Mutant causing more of rarer sex at advantage. Also changes if individuals of a sex have different chances of mating. Biases in Sex Ratio 1.
Improved condition affects fitness of one sex more than another.
Highly structured populations. If there is intense competition among males, sex ratio may be biased towards females. Local resource competition. Degree to which offspring help or hinder parents may affect sex bias. Allows existence at lower densities.