What Is The Genetic Makeup Of An Organism Of Asexual Reproduction

Chapter 24. Fauna Reproduction and Development

24.1. Reproduction Methods

Learning Objectives

By the end of this section, y'all will be able to:

• Describe advantages and disadvantages of asexual and sexual reproduction
• Hash out asexual reproduction methods
• Hash out sexual reproduction methods

Animals produce offspring through asexual and/or sexual reproduction. Both methods accept advantages and disadvantages. Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. A unmarried individual tin can produce offspring asexually and large numbers of offspring tin be produced quickly. In a stable or anticipated environment, asexual reproduction is an effective means of reproduction because all the offspring volition be adapted to that environment. In an unstable or unpredictable environment asexually-reproducing species may be at a disadvantage considering all the offspring are genetically identical and may non take the genetic variation to survive in new or different conditions. On the other hand, the rapid rates of asexual reproduction may let for a speedy response to environmental changes if individuals accept mutations. An boosted advantage of asexual reproduction is that colonization of new habitats may be easier when an individual does non demand to notice a mate to reproduce.

During sexual reproduction the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents. The genetic diversity of sexually produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment. Species that reproduce sexually must maintain 2 different types of individuals, males and females, which tin can limit the power to colonize new habitats as both sexes must be present.

Asexual Reproduction

Asexual reproduction occurs in prokaryotic microorganisms (leaner) and in some eukaryotic unmarried-celled and multi-celled organisms. There are a number of ways that animals reproduce asexually.

Fission

Fission, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. Afterwards a period of growth, an organism splits into two split up organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, role of the individual separates and forms a second individual. This procedure occurs, for example, in many asteroid echinoderms through splitting of the cardinal disk. Some sea anemones and some coral polyps (Figure 24.2) also reproduce through fission.

Figure 24.2.  Coral polyps reproduce asexually by fission. (credit: G. P. Schmahl, NOAA FGBNMS Manager)

Budding

Budding is a class 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 ii individuals. Budding occurs normally in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the primary body, as illustrated in Figure 24.three, whereas in coral budding, the bud does not disassemble and multiplies as part of a new colony.

Figure 24.3.  Hydra reproduce asexually through budding.

Watch a video of a hydra budding.

Fragmentation

Fragmentation is the breaking of the torso into 2 parts with subsequent regeneration. If the animal is capable of fragmentation, and the part is big enough, a split up private will regrow.

For example, in many bounding main stars, asexual reproduction is accomplished by fragmentation. Figure 24.4 illustrates a body of water star for which an arm of the individual is broken off and regenerates a new sea star. Fisheries workers have been known to try to kill the ocean stars eating their mollusk or oyster beds by cut them in half and throwing them back into the body of water. Unfortunately for the workers, the ii parts tin each regenerate a new one-half, resulting in twice every bit many bounding main stars to prey upon the oysters and clams. Fragmentation as well occurs in annelid worms, turbellarians, and poriferans.

Figure 24.four.  Sea stars can reproduce through fragmentation. The large arm, a fragment from some other sea star, is developing into a new individual.

Notation that in fragmentation, there is more often than not a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed.

Parthenogenesis

Parthenogenesis is a grade of asexual reproduction where an egg develops into a complete individual without beingness fertilized. The resulting offspring tin can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water flees, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees utilise 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 blazon of bee produced.

Some vertebrate animals—such as certain reptiles, amphibians, and fish—also reproduce through parthenogenesis. Although more common in plants, parthenogenesis has been observed in animal species that were segregated by sex in terrestrial or marine zoos. Two female Komodo dragons, a hammerhead shark, and a blacktop shark have produced parthenogenic young when the females accept been isolated from males.

Sexual Reproduction

Sexual reproduction is the combination of (unremarkably haploid) reproductive cells from two individuals to grade a third (normally diploid) unique offspring. Sexual reproduction produces offspring with novel combinations of genes. This can be an adaptive advantage in unstable or unpredictable environments. As humans, nosotros are used to thinking of animals as having two dissever sexes—male and female person—determined at conception. Even so, in the animal kingdom, there are many variations on this theme.

Hermaphroditism

Hermaphroditism occurs in animals where one individual has both male and female reproductive parts. Invertebrates such every bit earthworms, slugs, tapeworms and snails, shown in Effigy 24.5, are oft hermaphroditic. Hermaphrodites may cocky-fertilize or may mate with some other of their species, fertilizing each other and both producing offspring. Cocky fertilization is mutual in animals that accept limited mobility or are non motile, such as barnacles and clams.

Figure 24.five.  Many snails are hermaphrodites. When 2 individuals mate, they tin can produce upward to one hundred eggs each. (credit: Assaf Shtilman)

Sex Conclusion

Mammalian sexual practice decision is determined genetically by the presence of X and Y chromosomes. Individuals homozygous for Ten (Twenty) are female person and heterozygous individuals (XY) are male. The presence of a Y chromosome causes the development of male characteristics and its absence results in female characteristics. The XY system is too constitute in some insects and plants.

Avian sex determination is dependent on the presence of Z and W chromosomes. Homozygous for Z (ZZ) results in a male and heterozygous (ZW) results in a female. The Due west appears to be essential in determining the sex of the individual, similar to the Y chromosome in mammals. Some fish, crustaceans, insects (such as butterflies and moths), and reptiles use this arrangement.

The sex activity of some species is not determined past genetics simply by some attribute of the environment. Sexual activity determination in some crocodiles and turtles, for example, is frequently dependent on the temperature during critical periods of egg development. This is referred to as environmental sexual practice conclusion, or more specifically as temperature-dependent sex determination. In many turtles, libation temperatures during egg incubation produce males and warm temperatures produce females. In some crocodiles, moderate temperatures produce males and both warm and cool temperatures produce females. In some species, sex is both genetic- and temperature-dependent.

Individuals of some species change their sex during their lives, alternating between male person and female person. If the private is female person beginning, information technology is termed protogyny or "first female person," if it is male person first, its termed protandry or "beginning male person." Oysters, for instance, are born male, grow, and go female and lay eggs; some oyster species change sex activity multiple times.

Summary

Reproduction may exist asexual when one individual produces genetically identical offspring, or sexual when the genetic textile from two individuals is combined to produce genetically diverse offspring. Asexual reproduction occurs through fission, budding, and fragmentation. Sexual reproduction may mean the joining of sperm and eggs within animals' bodies or it may hateful the release of sperm and eggs into the surroundings. An individual may be one sex, or both; it may first out as one sexual activity and switch during its life, or information technology may stay male or female.

Exercises

1. Which form of reproduction is thought to be best in a stable environment?
   1. asexual
   2. sexual
   3. budding
   4. parthenogenesis
2. Which form of reproduction can result from damage to the original animal?
   1. asexual
   2. fragmentation
   3. budding
   4. parthenogenesis
3. Which form of reproduction is useful to an animate being with little mobility that reproduces sexually?
   1. fission
   2. budding
   3. parthenogenesis
   4. hermaphroditism
4. Genetically unique individuals are produced through ________.
   1. sexual reproduction
   2. parthenogenesis
   3. budding
   4. fragmentation
5. Why is sexual reproduction useful if simply one-half the animals can produce offspring and two separate cells must be combined to form a third?
6. What determines which sexual practice will upshot in offspring of birds and mammals?

Answers

1. A
2. B
3. D
4. A
5. Sexual reproduction produces a new combination of genes in the offspring that may better enable them to survive changes in the environment and assist in the survival of the species.
6. The presence of the Westward chromosome in birds determines femaleness and the presence of the Y chromosome in mammals determines maleness. The absenteeism of those chromosomes and the homogeneity of the offspring (ZZ or 20) leads to the development of the other sexual activity.

Glossary

asexual reproduction

form of reproduction that produces offspring that are genetically identical to the parent

budding

form of asexual reproduction that results from the outgrowth of a role of a cell leading to a separation from the original animal into 2 individuals

fission

(also, binary fission) method past which multicellular organisms increase in size or asexual reproduction in which a unicellular organism splits into ii separate organisms by mitosis

fragmentation

cutting or fragmenting of the original animal into parts and the growth of a separate fauna from each part

hermaphroditism

country of having both male person and female reproductive parts within the same individual

parthenogenesis

form of asexual reproduction where an egg develops into a complete individual without being fertilized

sexual reproduction

mixing of genetic material from 2 individuals to produce genetically unique offspring

Source: https://opentextbc.ca/biology/chapter/24-1-reproduction-methods/

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