If males are common, they produce more females. This is determined by how long it is after ovulation that a female is fertilized. E. Population Growth. If a species periodically experiences opportunities for population explosion, might favor more females because this will favor more rapid growth. This happens in wood lemmings.
Species is diploid.
A. ESD is adaptive in life history where the environment that offspring enter has a gender-dependent influence on fitness. For example, if large body size is more important to the reproductive success of females than males, those members of a population that enter an environment allowing rapid growth should become female, whereas those individuals encountering poor growing conditions would make the best of a bad situation and become male. Neither parents or offspring can control which type of patch offspring enter. Under these conditions, genetic sex determination would lead to individuals often having the sex of the lower fitness for their particular environment. ESD allows sex ratios to be adjusted in response to specific environmental conditions.