Jumping Spider Dances: Sex
ratios and Operational Sex Ratios
The "sex ratio" in a population is the ratio of females to
males. If there are equal numbers of males and females, the ratio is 1
: 1.
However, although there may be equal numbers of males and females, the
"operational sex ratio" (ratio of sexually receptive males to
sexually receptive females) can be quite different. If half the females
are already mated, or if half the males are sexually immature and can't
mate yet, the "operational sex ratio" will be quite different
from the actual sex ratio.
Males have enough sperm to inseminate many females (with sperm to spare).
Females can only produce 10 eggs at a time, and one mating can easily
fertilize all the eggs.
Therefore, because the potential rate of reproduction is quite different
between the sexes, at any one time there are many more sexually receptive
males than sexually receptive females.
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