Reproduction is vital for the survival of any species. Different organisms use different methods to reproduce. One of these methods is sexual reproduction, which has its own advantages and disadvantages.
WHAT IS SEXUAL REPRODUCTION?
Sexual reproduction is the method by which living organisms produce offspring by the process of fertilization. This process in seen in higher organisms. This involves a gamete that travels to fuse itself with a larger stationary gamete produced. The smaller gamete that travels to a larger one is produced by the male. This is known as the sperm cell. The large gamete is produced by the female. It is known as the ovum or the egg.
The process of the sperm and ova merging is known as fertilisation.
Fertilisation creates a single-celled zygote which includes genetic material from both gametes. In a process called genetic recombination, genetic material (DNA) joins up so that chromosome sequences are aligned with each other, and this is followed by exchange of genetic information. The exchange of genetic information decides the traits of the offspring.
After this, the cells begin diving themselves. The genes of both parents are stored in one cell each. These cells divide themselves into 2, and produce four daughter cells with half the number of chromosomes from each original parent cell. Any two of these 4 cells can combine and decide the traits for the offspring. For instance, in human reproduction, each human cell contains 46 chromosomes in 23 pairs. Each parent provides 23 chromosomes, resulting in a total of 46 for the offspring
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WHAT IS THE OPPOSITE OF SEXUAL REPRODUCTION?
Asexual reproduction can be defined as the process by which offspring are produced from a single parent rather than through fertilization. It is most common in environments that favour rapid population growth over genetic diversity. It is found in organisms like planarians, annelid worms, sea stars and species of fungi.
There are 5 types of asexual reproduction, spores, fission, vegetative reproduction, budding, and fragmentation.
Spores are structures that grow naturally as part of an organism’s life cycle. They are designed for separation from the organism and dispersal via air or water. When conditions are correct, the organism releases its spores. These individual spores are then considered entirely separate and autonomous organisms.
Fission occurs at the cellular level. A cell’s contents are replicated internally and then subjected to division. The cell then forms into two distinct entities and separates itself. Budding is a process by which an entirely new organism grows on an existing one. The developing organism begins its life as an entirely separate life form from its “parent”, separating into an autonomous entity only when it has fully matured.
An organism that reproduces via fragmentation physically splits and develops new, genetically identical organisms out of each segment. The segments rapidly grow new cells to constitute their muscle fibre and internal structure through mitosis. Another form of asexual reproduction is vegetative reproduction. In plants, multicellular structures become detached from the parent plant and develop into new individuals that are genetically identical to the parent plant.
Does sexual reproduction reign supreme?
Let’s find out.
Advantages of Sexual Reproduction
In sexual reproduction, two parties are involved. These two parties contribute their genes and characteristics to form an entirely new organism. This ensures that the offspring isn’t exactly like one of the parents. Their features might be similar or overlap, but they will not be 100% same. In humans, this can be seen in the differences of eye colour, hair colour, skin colour, height, et cetera. The combination of two genetic material donations allows for there to be a higher level of genetic diversity, which is necessary to keep the general population of any species healthy.
On the other hand, asexual reproduction involves only one parent. This means that the offspring produced is the exact copy of the parent. All features of the parent organism, negative or positive, are found in the offspring.
Reduced Chance of Genetic Disease
In asexual reproduction, the offspring is an exact copy of the parent. This means that any disease that the parent suffers from will definitely be passed on to the offspring. Unless mutations occur during cell reproduction, the offspring will necessarily be a clone. However, in sexual reproduction, this is not true. Two different donations of genetic materials are combined, and nature picks and chooses genes from them. This greatly reduces the chances of a genetic disease being transferred. Even when both parents are a carrier for a specific disease or condition, the rate of transference is typically 50%.
Charles Darwin introduced a principle called the “survival of the fittest”. This meant that by the process of natural selection, the species that are best suited to their environment are the most likely to survive. In this process of reproduction, traits that are beneficial are passed on to the offspring. This allows the species to begin to evolve on micro-levels, and potentially on macro-levels as well.
In the event that it does not lead to evolution, it allows the elimination of undesirable traits or genes. By identifying high-risk individuals and restricting their access to breeding, it is possible to eliminate certain poor genetic profiles. These restrictions can be seen in some species, such as horses.
Improves Mental and Physical Health
Indulging in sexual reproduction has been linked to various health benefits. In humans, it leads to the secretion of dopamine, known as the “happy hormone”. This can function as an antidepressant. It can help to relieve pain. A 2010 finding by Princeton scientists discovered that sexually active creatures experience brain growth compared to creatures that are not sexually active.
In males, it lowers the risk of developing heart disease. Additionally, it can also promote a stronger immune system, stronger muscles, and may even lower certain cancer risks.
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Disadvantages of Sexual Reproduction
Asexual reproduction needs only one parent organism to produce an offspring. Newer organisms can be reproduced as and when required. However, sexual reproduction requires two organisms. These organisms must also be from sexes that are compatible for reproduction. This increases the time and efforts that are needed in order to reproduce. In some species, mating calls are required in order to convince the other organism to participate in the process of reproduction. Usually, is the auditory signal used by animals to attract mates.
Given that there are no variables involved in asexual reproduction, offsprings are produced in every case. The parent organism initiates the process of reproduction, and at the end of it, an offspring is born. However, in sexual reproduction, it does not work this way. There is no guarantee of an offspring being born. There are multiple things that can prevent successful reproduction. For instance, the chosen partner might be infertile. The gestation period is also very long, which provides a long time window for variables to go wrong.
Fewer Number of Offsprings
There is a limit on the number of offspring that can be born from sexual reproduction at a time. In some cases the number might increase, but humans typically have one child through reproduction. Horses usually have one foal whereas cats and dogs have nearly a dozen in a litter. Sexual reproduction encourages greater quality in the genetic profile, but there are usually lower population numbers because of this trend. Asexual reproduction occurs with greater frequency and better certainty.
Pros and Cons of Sexual Reproduction
|Reduced chance of genetic disease||
|Fewer number of offsprings|
|Improves mental and physical health||