Sexual reproduction is related to processes involving the exchange and mixing of genetic material between individuals of the same species. Individuals who arise through sexual reproduction resemble their parents, but are not identical with them.
This mode of reproduction, while more complex and more costly than asexual reproduction, has great advantages for living beings and is most widely employed by different groups. Even organisms that have asexual reproduction can also reproduce sexually, although there are some species where sexual reproduction does not occur.
If our environment were completely stable, unchanged over time, asexual reproduction would be very advantageous because it would preserve, without modification, the characteristics of organisms for a certain ecological condition. This, however, is not reality. The environment can always change. Surviving them largely depends on whether genetic heritage contains as many solutions as possible.
Coloring is a type of variability.
Populations of genetically identical individuals, such as those originating from asexual reproduction, are more susceptible to environmental change. If an unfavorable change occurs in the environment, all individuals can die at once. This may not happen with populations of individuals who reproduce sexually, because the genetic variability between them is greater. This environmental change may affect part of the population, but another part survives by having in its genetic material conditions to resist the change.
In agriculture, asexual reproduction of plants is widely used to maintain commercially important characteristics over the generations. The use of this feature, however, allows whole crops to be wiped out if any alteration occurs that harms these organisms.
In animals, sexual reproduction involves meiosis, whose products are always gametes, haploid reproductive cells. Male gametes are sperm and female gametes are eggs.
In most animals, sperm are produced by the male individual and the eggs are produced by the female individual. In such cases, the sexes are separated. Some animals, however, such as earthworms, are hermaphrodites, because eggs and sperm are produced by the same individual.
In hermaphrodites, self-fertilization may occur, that is, egg fertilization by the sperm of the same individual. Occurs in some plant species. However, there are usually mechanisms that prevent self-fertilization. In such cases, the eggs of one individual are fertilized by the sperm of another individual of the same species. Then we talk about cross fertilization.
Earthworms cross fertilize