Evolution of Sexual Reproduction Essay

Submitted By m_Salus
Words: 2125
Pages: 9

Why Having Sex is Beneficial
Abstract
Reproduction is the biological process by which new offsprings of individual organisms are produced. It is a fundamental process to life and organisms exist as the result of reproduction. Sexual and asexual reproductions are the two main types of reproduction. In asexual reproduction, an organism can reproduce without the involvement of another individual of its same species. Asexual reproduction is mostly limited to sing-celled organisms. On the contrary, sexual reproduction requires the fusion (combination) of two different individuals to form a gamete. This type of reproduction is mostly observed in multicellular organisms. Through evolution, sexual selection has been deemed more advantageous than asexual reproduction in a variety of situations. The advantage of sex is explained through the refutation of the sexual reproduction paradox, Red Queen’s Hypothesis, and Muller’s Rachet and its influence on the theories and evolution of sexual reproduction.
Introduction
Reproduction is essential for the survival and evolution of a species. It is through reproduction in which an individual passes on its genes to the next generation. Most multicellular species reproduce sexually where each parent contributes half of its genes to the offspring. This fusion of genes results in an offspring that is similar but also genetically different from their parents. The difference of genetic make-up between generations allows for sexually reproducing organisms to adapt more quickly to changing conditions in the niche (Futuyma, 2009). This increases the chances of these individuals to live long enough to reproduce and pass on their genes to the next generation, thus allowing them to have a greater influence on the genetic make-up of their species.
In contrast, asexual reproduction does not require the pairing of two different organisms to produce an offspring. Species with asexual reproduction (such as bacteria and protists) are able to pass on its complete genome to the next generation. Asexually reproducing species can establish a new colony/population faster than sexually reproducing species since it does not need a sexual partner to reproduce (Futuyma, 2009). However, since individuals that undergo asexual reproduction are genetically similar within a species, it takes longer for these populations to evolve in response to the changes around them which makes them more vulnerable to changes in climate or other agents that can wipe them out.
Today, all sexually reproducing organisms are derived from a common ancestor which was a single celled eukaryotic species. The evolution of sex mostly focuses on two themes: its origin and its maintenance. Studies have shown that sexual reproduction is maintained because it improves the quality of progeny in species. The great improvement of fitness from sexual reproduction is in the creation of genetic variation. Genetic variation proves to be incredibly advantageous in recombination DNA repair and in masking mutations through complementation. Recombination DNA repair is able to remove DNA damaged during meiosis and this allows for greater survival of the organism (Bert, 2000). Complementation in sexual reproduction is able to remove deleterious mutations quicker though masking the deleterious genes with either a normal dominant gene or through the elimination of the organism containing the deleterious genotype and exhibiting the deleterious function. Sex can also create new gene combinations that may be more fit than the preexisting ones and thus allow organisms to have a better survival and reproduction rates (Bert, 2000).
Refuting the Paradox of Sexual Reproduction
The common explanation of the existence of recombination and sex is that they increase the rate of adaptive evolution of a species in a constant or changing environment and thus reducing the risk of extinction. However, sex and recombination also have its disadvantages. One example is that…