Females can be fertilized by several males because the sperm share space once inside the female. As a result, different types of adaptations have appeared to ensure the reproductive success of males. Two types of adaptations can be distinguished:
1. TO ACHIEVE A PREFERENTIAL USE OF SPERM. The best known case is that of some dragonflies. The male reproductive system has a special structure called horn of the penis. With this structure, the male gains access to the female’s spermatheca (where the sperm of the males who have fertilized her is stored) and extracts any sperm from other males. It will then transfer its spermatophores.
2. AVOID THE MATING OF OTHER MALES:
a) Through vaginal plugs, created from secretions of the males, preventing others from mating. They can be hardened secretions, the ejaculate itself or a structure called “sphragis“, a kind of mold of the male’s genitalia from secretions that it leaves attached to the female.
b) Prolonged copulations, so that after mating, males remain attached to the female for hours or even days.
c) Chemical repulsion thanks to a dispersion pheromone released by males which prevents others from approaching the female.