How many types of reproduction are there

Organisms that reproduce through asexual reproduction tend to grow in number exponentially. However, because they rely on mutation for variations in their DNA, all members of the species have similar vulnerabilities.

Organisms that reproduce sexually yield a smaller number of offspring, but the large amount of variation in their genes makes them less susceptible to disease. Many organisms can reproduce sexually as well as asexually. Aphids, slime molds, sea anemones, and some species of starfish are examples of animal species with this ability. When environmental factors are favorable, asexual reproduction is employed to exploit suitable conditions for survival, such as an abundant food supply, adequate shelter, favorable climate, disease, optimum pH, or a proper mix of other lifestyle requirements.

Populations of these organisms increase exponentially via asexual reproductive strategies to take full advantage of the rich supply resources. When food sources have been depleted, the climate becomes hostile, or individual survival is jeopardized by some other adverse change in living conditions, these organisms switch to sexual forms of reproduction.

Sexual reproduction ensures a mixing of the gene pool of the species. The variations found in offspring of sexual reproduction allow some individuals to be better suited for survival and provide a mechanism for selective adaptation to occur. In addition, sexual reproduction usually results in the formation of a life stage that is able to endure the conditions that threaten the offspring of an asexual parent.

Asexual and sexual reproduction, two methods of reproduction among animals, produce offspring that are clones or genetically unique.

Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. This type of reproduction occurs in prokaryotic microorganisms bacteria and in some eukaryotic single-celled and multi-celled organisms. Animals may reproduce asexually through fission, budding, fragmentation, or parthenogenesis. Fission, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms.

After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates, forming a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps also reproduce through fission.

Fission : Coral polyps reproduce asexually by fission, where an organism splits into two separate organisms. Budding is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals.

Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult, which breaks away from the main body; whereas in coral budding, the bud does not detach and multiplies as part of a new colony. Budding : Hydra reproduce asexually through budding, where a bud forms that develops into an adult and breaks away from the main body.

If the animal is capable of fragmentation, and the part is big enough, a separate individual will regrow. Many sea stars reproduce asexually by fragmentation. For example, if the arm of an individual sea star is broken off it will regenerate a new sea star. Fishery workers have been known to try to kill the sea stars that eat their clam or oyster beds by cutting them in half and throwing them back into the ocean.

Unfortunately for the workers, the two parts can each regenerate a new half, resulting in twice as many sea stars to prey upon the oysters and clams. Fragmentation also occurs in annelid worms, turbellarians, and poriferans. Note that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximately the same size are formed.

Parthenogenesis is a form of asexual reproduction where an egg develops into a complete individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water fleas, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees use parthenogenesis to produce haploid males drones and diploid females workers.

If an egg is fertilized, a queen is produced. The queen bee controls the reproduction of the hive bees to regulate the type of bee produced. The similarity of DNA between individuals in a population of clones can make it easier for these species to be wiped out by diseases. Sarala Pradhan, Ioulia Bespalova. To Breed or Not to Breed. Scientists, teachers, writers, illustrators, and translators are all important to the program.

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Many bacteria reproduce by binary fission. The parent bacterial cell produces two identical clone cells by first creating a copy of the DNA molecule.

Then, this is followed by chromosome segregation wherein DNA is pulled apart toward the opposite poles of the dividing cell. The cell constricts at the equatorial plane cytokinesis , separating the cellular contents into two new cells. The process is similar to mitosis in eukaryotes. However, there is no spindle apparatus involved.

The duration varies between bacterial species. When food is scarce and the conditions are not suitable, plasmodium slime molds produce stalked reproductive fruiting bodies sporangia that contain spores. At the apical portion of the sporangia, the cells undergo meiosis, producing haploid spores that are dispersed by wind.

When the conditions become favorable again, e. The haploid cells are involved in the sexual phase of the plasmodium slime mold life cycle. Cellular slime molds also have asexual and sexual phases in their life cycle. However, when the conditions are not favorable, they come together as a pseudoplasmodium. They form a pseudoplasmodium because the cells remain distinct, each with a nucleus of its own.

A real plasmodium in slime molds is a single mass of cytoplasm undivided by membranes and containing multiple nuclei. Nevertheless, both the cellular slime molds and plasmodium slime molds produce fruiting bodies.

Some of the cellular slime molds in the colony form the stalk whereas the others form the sporangium where haploid spores are produced and released from. Each spore germinates into an individual amoeba-like cell. The New Mexico whiptails Aspidoscelis neomexicanus are lizards that are all females. They reproduce asexually by parthenogenesis by doubling the chromosomal number twice to restore diploidy.

So to begin with, they produce eight copies of each chromosome. Thus, after two rounds of cell division, four daughter cells, each with two sets of chromosomes instead of just one. Although they do not need a male mate, they still display mating behavior with other females. A female whiptail mounts another female whiptail.

This pseudocopulation behavior seemingly promotes ovulation. While other asexuals produce genetic clones, the New Mexico whiptails are still able to produce genetically-diverse offspring.

How is that possible? Do you think humans are capable of reproducing asexually? Come and share with us what you think. Try to answer the quiz below to check what you have learned so far about asexual reproduction.

Smith, J. Maynard The Evolution of Sex. Cambridge University Press. ISBN Otto, S. Sexual Reproduction and the Evolution of Sex. Nature Education 1 1 Fields, A. Facultative parthenogenesis in a critically endangered wild vertebrate. Current Biology, 25 11 , R—R Wikipedia Contributors. Wikipedia; Wikimedia Foundation. Sezonov, G. Journal of Bacteriology. PMC Chapter Concept Yong, E. Extra chromosomes allow all-female lizards to reproduce without males. Discover Magazine; Discover Magazine.

How an Asexual Lizard Procreates Alone.