In nature, a 50:50 ratio is maintained for male and female.
Even though it can be stated that having less numbers of males and a lot of female, is far more efficient than other but to calculate roughly, each number of sexes are born every season. This is true for all animal species present in the earth.
In nature, this equal ratio is so common that it makes us wonder why it is this way. The ratio we are talking about is the biological sex, not gender. In biology we have learned that the male sperm contain the XY chromosome and the female egg contains the XX chromosome. Therefore, there’s a 50% probability of production of either sex.
Main Point Of Evolution?
If getting your genes from one generation to the next is the whole point of evolution, then just by putting a lot of eggs into female ovum can crack the deal. Usually, males produce a lot of sperm. Thus only a few males is enough to keep the population churning. This can be considered as an ideal situation.
Now, consider a hypothetical population, where out of 10, 9 are born female and 1 is male. During mating each male will mate 9times as often as a female. If every such meeting results in 2new people for the next generation, then it can be said that 18 offspring have carried each male’s gene and only 2 offspring carries the female genes.
Thus, according to the fitness score the male leads the female by 9 times. But if the whole scenario is reversed i.e., if out of 10, 9are male and 1 is female then the offspring would have a huge advantage over the other. This mutation will spread there will be a lot more male than females. As female is rare, then the parent with extra female offspring would be favoured. Now that will go on until female’s ratio is more. Thus, this imbalance will continue infinitely until a 50:50 ratio is reached.
So, this is why we see this ratio again and again. As this is the only way which is evolutionary stable.