Sexual reproduction is a type of reproduction where organisms are created by combining the genetic information from two individuals of different sexes. The genetic information is carried on chromosomes within the nucleus of specialized sex cells referred to as gametes. In males, these gamates are referred to as sperm and in females the gamates are referred to as eggs. Therefore, during sexual reproduction the two gamates fuse together in a process referred to as fertilization, to create a zygote. The zygote then develops into an embryo offspring, taking half of its DNA from each of its parent. For example in humans, a zygote contains 46 chromosomes, that is, 23 from the mother and 23 from the father. Sexual reproduction is the means of reproduction in humans and animals.
Types of Sexual Reproduction
- Autogamy also referred to as self-fertilization or self-pollination, is the fusion of male and female gamates, which are produced by a single individual. This type of reproduction is common in most plants and earthworms.
- Allogamy, this type of sexual reproduction occurs when the gamates which fused together during fertilization came from two different individuals.
Characteristics Of Sexual Reproduction You Need To Know
- Sexual reproduction is biparental. Biparental means that, two parents are involved in the production of progenies through sexual reproduction.
- Sex organs are usually involved.
- In many instances, the number of progenies produced through sexual reproduction will be limited.
- The unit of reproduction is gamate of parents.
- In sexual reproduction, formation of gamates and union of gamates (fertilization) are involved.
- Sexual reproduction is usually found in higher invertebrates and all vertebrates.
- Sexual reproduction can take a long period of time to complete i.e several months.
- Sexual reproduction has some evolutionary significance given that it leads to genetic variation in new generations of offspring.
- Meiosis is essential for sexual reproduction. Meiosis ensures that the reduction of chromosome number to haploid number.
- In sexual reproduction, the new progeny arises from the zygote.
- In sexual reproduction, the progenies will be genetically different from the parents.
- Types of sexual reproduction include: Syngamy and conjugation.
- Example of sexual reproduction include: Reproduction in humans, Animals etc.
What Are Some Of Advantages And Disadvantages Of Sexual Reproduction?
- It results in genetic diversity within a species.
- Genetic variations can result to evolutionary advancements.
- It improves the overall health of a species.
- Sexually reproduced species can quickly adapt to changes in the environment.
- Unfavorable genetic characteristics can be passed to the offspring.
- Finding a mate can be time and energy consuming.
- Fewer offspring are produced through sexual reproduction.
- Reproduction is not 100% certain because some mates can be infertile.
Asexual reproduction is a type of reproduction whereby offspring are produced from a single parent rather than through fertilization. Asexual reproduction produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. Asexual reproduction occurs in prokaryotic microorganisms and in some eukaryotic single-celled and multi-celled organisms. Example of organism that reproduce asexually include:
- Hydra (jelly fish)
- Some flowering plants such as strawberries
Asexual reproduction is very much common in environments that favor rapid population growth over genetic diversity, as the offspring inherits its genetic traits completely from one parent. Usually, in stable environment, asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment.
Types Of Asexual Reproduction
- Binary Fission: This is a type of asexual reproduction in which a cell simply copies its DNA and then split into two. It occurs in prokaryotic microorganisms and in some invertebrates and in multi-celled organisms. Also some unicellular eukaryotic organisms reproduce by binary fission through mitosis.
- Budding: Budding is a form of asexual that results from the outgrowth of a part of a cell or body region leading to separation from the original organism into two individuals. It is common in invertebrates like hydra and corals.
- Fragmentation: In fragmentation, a parent-organism is split into multiple parts; each part (offspring) eventually grows to become a complete, independent organism. This type of asexual reproduction is common in earthworms, plants and in some sea creatures. These organisms have ability to regenerate from fragments following injuries that happen to split them into multiple pieces.
- Parthenogenesis: This is a type of asexual reproduction whereby, an egg develops into a complete offspring without being fertilized. Parthenogenesis is common in invertebrates such as water flees, stick insects, rotifers, ants, wasps, bees and aphids.
- Sporogenesis: Sporegenesis also referred to as agemenogenesis, is a type of asexual reproduction whereby, a new organism (offspring) develops from spores.
- Vegetative Propagation: This is a type of reproduction whereby a plant grows a new shoot which is capable of becoming a whole new organism.
Characteristics Of Asexual Reproduction You Need To Know
- Asexual reproduction is uniparental. What this means is that progenies are produced from a single parent.
- Sex organs are never involved.
- In many instances, large numbers of progenies are produced through asexual reproduction.
- The unit of reproduction may be whole parent body or a bud or a fragment or a single somatic cell.
- In asexual reproduction, formation of gamates and union of gamates (fertilization) are never part of it.
- Asexual reproduction is usually found in lower organisms.
- Asexual reproduction is completed in a very short period of time.
- Asexual reproduction does not have an evolutionary significance because there is very little chance of genetic variations in new generation of offspring. Yes, mutation in DNA can still occur but not nearly as frequent as in sexual reproduction.
- Meiotic cell division is absent in asexual reproduction, all cells divide by fission, budding, or regeneration.
- In asexual reproduction, the new progeny arise from a single cell or from a part of the parent.
- In asexual reproduction, the progeny and the parent will be genetically similar.
- Types asexual reproduction include: Budding, vegetative reproduction, fragmentation and spore formation etc.
- Examples of asexual reproduction include: Bacterial fission, budding of yeast, budding of Hydra etc.
What Are Some Of The Advantages And Disadvantages Of Asexual Reproduction?
- The energy required for reproduction is minimal.
- Maturity is rapid
- Only one organism is required for reproduction.
- It can occur in various in various environments.
- There are multiple forms of asexual reproduction.
- Due to the fact that only one parent is involved in reproduction, diversity is limited.
- Population numbers can bring a challenge in as far as control is concern due to overcrowding.
- The problem of adaptation may arise. Asexual organisms are not always able to adapt to a changing environment or habitat.
- Asexual organisms majorly have a short lifespan.
- Negative mutations are common in asexual organisms because the offspring is typically a clone of the parent.
Difference Between Asexual And Sexual Reproduction In Tabular Form
|BASIS OF COMPARISON||SEXUAL REPRODUCTION||ASEXUAL REPRODUCTION|
|Description||Sexual reproduction is biparental. Biparental means that, two parents are involved in the production of progenies through sexual reproduction.||Asexual reproduction is uniparental. What this means is that progenies are produced from a single parent.|
|Sex Organs||Sex organs are usually involved.||Sex organs are never involved.|
|Number Of Progenies||The number of progenies produced through sexual reproduction will be limited.||Large numbers of progenies are produced through asexual reproduction.|
|Unit Of Reproduction||The unit of reproduction is gamate of parents.||The unit of reproduction may be whole parent body or a bud or a fragment or a single somatic cell.|
|Fertilization||Formation of gamates and union of gamates (fertilization) are involved.||Formation of gamates and union of gamates (fertilization) are never part of it.|
|Presence||It is usually found in higher invertebrates and all vertebrates.||It is usually found in lower organisms.|
|Completion Time||Reproduction can take a long period of time to complete i.e several months.||Reproduction is completed in a very short period of time.|
|Evolutionary Significance||It has some evolutionary significance given that it leads to genetic variation in new generations of offspring.||It does not have an evolutionary significance because there is very little chance of genetic variations in new generation of offspring.|
|Cell Division||Meiosis is essential for sexual reproduction. Meiosis ensures that the reduction of chromosome number to haploid number.||Meiotic cell division is absent in asexual reproduction, all cells divide by fission, budding, or regeneration.|
|New Progeny||The new progeny arises from the zygote.||The new progeny arise from a single cell or from a part of the parent.|
|Genetic Variation||The progenies will be genetically different from the parents.||The progeny and the parent will be genetically similar.|
|Types||Allogamy andAutogamy||Budding, vegetative reproduction, fragmentation and spore formation etc.|
|Examples||Reproduction in humans, Animals etc.||Bacterial fission, budding of yeast, budding of Hydra etc.|