The reproduction of living beings is a biological process through which organisms create offspring, which is of vital importance to perpetuate the species. Two types of reproduction are recognized: sexual reproduction and asexual reproduction, which in turn are subdivided into others. Let’s look at each one below.
Asexual reproduction
Asexual reproduction is one where only one parent is necessary to create a descendant organism. In this type of reproduction, a parental individual fragments, splits or divides, giving rise to one or more individuals with the same genetic load, unless a mutation occurs.
Asexual reproduction can manifest itself in both unicellular and multicellular organisms. It has the peculiarity of generating identical descendants.
Types of asexual reproduction
There are various types of asexual reproduction, such as binary fission, parthenogenesis, budding, fragmentation, sporulation and vegetative multiplication.
Binary fission
A parent organism duplicates its DNA and then divides into two identical cells.
For example, bacteria and archaea.
Fragmentation
The parent organism fragments or splits. From this fragment another individual with the same characteristics is generated.
For example, corals and starfish.
Gemmation
The parent organism generates a sprout that, when detached, gives rise to another organism.
For example, certain yeasts and sponges.
Stages of asexual reproduction of a hydra (budding).
Sporulation
The parent organism creates spores from which a new organism is formed.
For example, mold.
Parthenogenesis
It is produced from unfertilized female sex cells that give rise to another life. Although a female sex cell is involved, parthenogenesis is considered asexual because it is generated from a single parental individual.
For example, bees and certain types of insects.
Vegetative multiplication
It consists of the formation of new organisms from one part of another, such as a bulb, tubers or rhizomes.
For example, sweet potatoes, sweet potato or sweet potato.
You may be interested in Asexual reproduction.
sexual reproduction
Sexual reproduction is one that requires two parents, one female and the other male. Therefore, the offspring obtained are similar (not identical).
Through a cellular reproduction process called meiosiseach parent generates gametes (female and male respectively), which carry half of the genetic material that makes up a somatic cell.
When the gametes come into contact, fertilization occurs, resulting in the creation of a zygote. The zygote is the cell from which a new living being is generated.
For the gametes to come into contact, a process of fertilization. Fertilization can be carried out in three different ways: internal, external and autogamy.
Internal fertilization
Through mating, the gametes are fertilized and develop inside the female. Note: the Hippocampus kudaknown as the seahorse, is an exception to this rule as it is the only male capable of becoming pregnant.
For example, viviparous animals, including lions, zebras, apes and humans.
External fertilization
The parents shed sex cells into the environment, where fertilization occurs. It is common in the aquatic environment.
For example, vertebrate fish, crustaceans and a large part of algae, all belonging to the ovuliparous group.
Autogamy
Own of organisms with female and male sexual organs at the same time (hermaphrodites). These organisms can fertilize themselves under specific conditions.
For example, some species of flowers, among which roses and wheat flowers stand out.
Types of sexual reproduction
From a specialized point of view, sexual reproduction can be classified according to the morphological characteristics of the gametes.
Isogamous sexual reproduction
It takes its name from Greek terms isowhich means ‘equal’ and fallow deer, which means ‘marriage’. It corresponds to those species where the gametes of each parent are equal in size and shape. Therefore, it is not possible to distinguish between feminine and masculine.
For example, the reproduction of some kinds of fungi.
Anisogamous sexual reproduction
It takes its name from Greek terms anwhich means ‘denial or lack’, isowhich means ‘equal’ and fallow deer, which means ‘marriage’. It corresponds to those species where the gametes of each parent differ in shape and dimensions. This is the case of sperm and eggs.
For example, most mammals, such as cats, dogs or horses.
Sexual reproduction in animals
The modalities or forms of sexual reproduction in animals include viviparity, ovoviparity or oviparity (which includes ovuliparity).
Viviparity
In viviparous animals, fertilization and development of the embryo occurs inside the female, responding to internal fertilization.
For example, most mammals (with the exception of platypuses and echidnas). Therefore, human reproduction obeys this pattern.
Oviparity
Oviparous animals are those whose females lay eggs. These are fertilized by the male before spawning.
For example, birds and most reptiles.
Ovuliparity
Frog eggs.
Ovuliparity is a variant of oviparity. Applies to animals whose egg fertilization occurs after spawning. Qualifies as an external fertilization. It occurs in aquatic species.
For example, most fish, some crustaceans and certain amphibians such as frogs.
Ovoviparity
In ovoviparous animals, fertilization and development of the egg takes place inside the female, so that the new organism is ready to hatch after spawning.
For example, the asp viper and the sharks.
Sexual reproduction in plants
Plants reproduce through a process called pollination, whether anemophilous (induced by wind), hydrophilic (induced by water) or zoophilic (induced by animals).
Two basic types of sexual reproduction of plants are known: reproduction in angiosperms (flowers) and in gymnosperms (seeds without flowers).
Sexual reproduction in angiosperms
Angiosperms refer to flowering plants, in which the reproductive organs of the species are found.
For example, the orange trees, the coffee trees and the apple trees.
Sexual reproduction in gymnosperms
Gymnosperms refer to plants without flowers, called conifers. These plants contain elbows that carry the seeds.
For example, the pines and cedars.
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human reproduction
Human reproduction is a clear example anisogamic sexual reproduction by internal fertilization. Humans belong to the group of viviparous animals.
The human reproduction process consists of different stages.
Intercourse: refers to the copulatory act that allows the man to introduce male gametes (sperm) into the female reproductive system.
Fertilization: is the following process, in which the sperm joins with the female gamete (oocyte), resulting in the formation of a zygote.
Implantation: occurs when the zygote, converted into an embryo, implants itself in the walls of the uterus to develop.
Organogenesis: It is the stage in which the embryo develops its main organs.
Fetal development: It is the final stage, when the embryo becomes a fetus and completes its development process.
See also: Living things