maintaining functional characteristics.
maintaining functional characteristics.
Running head: LITERARY REVIEW
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LITERARY REVIEW
Natural selection maintains functional characteristics in ant species
Ashley Contreras
July 21, 2017
Henry Vo
Natural selection maintains functional characteristics in ant species.
The purpose of this review is to identify if natural selection plays a part in maintaining the status quo among ant populations. While it was initially thought that Random Genetic Drift could have a hand in maintaining functional characteristics, evidence shows that this is unlikely. Random Genetic Drift is an evolutionary process where genetic variations occur over time in a random manner. This process occurs under weak selection, affecting certain characteristics. This means that this process would be unimportant in maintaining functional characteristics. It is, therefore, thought that stabilizing selection, which is a form of natural selection, is responsible for maintaining functional characteristics. (Fisher, 2013). Comment by Contreras, Ashley M: Should be at the end of this paragraph. Start with an intro to natural selection Comment by Contreras, Ashley M: Describe the link between this selection and ant population then details can be discussed in the body
Some of the most important functional characteristics of ant species include a pair of leg spurs. These consist of a comb and a brush used for grooming. Grooming is essential for the ant as it helps in cleaning the highly sensitive antennae. With dirty antennae, the insect cannot follow a trail, smell food or even communicate with others. The font spur removes different sized particles from the antennae. The spur is covered with different types of hairs which make it resemble a lobster claw. When the antennae are pulled through this spur, particles of different sizes are removed and the insect can communicate effectively and as well, follow trails. The role of natural selection in maintaining the functional characteristics of the ant species can be identified by observing the genetic variations related to these parts. In most of the ant species, an insect has two pairs of spurs; a front spur, and a hind spur. Observing the genetic variation of these pairs of spurs could help in identifying the force at play in maintaining these functional characteristics. If both the front and the hind spurs are maintained by one force, then it can be expected that they do not show any genetic variations. (Freedman, 2007). Comment by Contreras, Ashley M: These three should be rewritten to become one topic sentence Comment by Contreras, Ashley M: Should be the topic sentence Comment by Contreras, Ashley M: Discuss genetic variations? You have only talked about their phenotypic variations
A research conducted on two molecular-phylogenetically indiscriminate ant species suggested that there could be different selective forces acting at different parts of the body of the ant species. The ant species used in this research had spurs projecting from the legs. The front spur is used to clean a sensory organ, the antennae, while the hind spur are occasionally used to clean the back surface of the ant’s abdomen. Given the importance of the front spur of the ant, due to its use in cleaning a major sensory organ of the ant and hence it unique brush-shape, natural selection forces can be assumed to play a big role on this spur. The hind spurs, on the other hand, have less functional importance. Natural selection forces can, therefore, be assumed to have no effect on the hind spur. (Phys.org, 2016). Comment by Contreras, Ashley M: Be more specific, my impression up to this point is that there are variation in phenotypes, but not clear on the factors that affect the genes/genetics to cause these variations Comment by Contreras, Ashley M: Discuss natural selection forces in details, this should be the focus of this review
There were significant differences between the two species of ant. This implied that gene flow between the two-ant species was highly limited. In addition to that, there was no evidence of inbreeding within the ant species. This was evidence that any morphological difference observed within or between the species populations was not a result of breeding or the flow of genes. These differences instead portrayed the impact natural selection has on these species’ characters. A comparison for both the front and hind spurs in the ant species showed that the front spurs had only a small degree of variation in terms of the length of the spur. However, the hind spurs, which are less important compared to the front spurs, showed significant variation in terms of length. This suggested the effect of the random genetic drift. (Darwin, 2010). Comment by Contreras, Ashley M: This should be a topic with more discussion within this paragraph, rather than a conclusion at the end
The conclusion was that there was a stabilizing selection force at play, which works to maintain the shape and size of the front spur in the ant species, which is highly useful in cleaning the antennae. The hind spur is not influenced by the stabilizing selection force. This is because the hind spur of the ant species has diversified over time. The stabilizing selection involved here is mostly associated with polygenic traits. The spur in the ant species is a polygenic trait. (Freedman, 2007). The fact that the ant species show uniformity in the front spur suggests that some other force must be acting on the Spurs to maintain the size and shape due to their importance. The major characteristic of stabilizing selection is that it favors the population of the species that is widely adapted to a certain environment. It often lowers diversity in the species because it leads to some kind of uniformity in a particular trait. For example, in the ant species, it leads to uniformity in the front spur. (Freedman, 2007).
Therefore, as opposed to Random Genetic Drift, natural selection plays an important role in maintaining the functional characteristics, especially in the ant species. Given its high functional importance, the front spur needs good maintenance compared to the hind spur. The genetic variation between the two pairs of spurs is what led to the conclusion that a different selection force is acting on each pair. The front pair is associated with natural selection due to its importance (Gibson, & Gibson, 2009).
References Comment by Contreras, Ashley M: The references need to be in alphabetical order
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Fisher, R. A. (2013). Genetical theory of natural selection. Place of publication not identified: Hardpress Ltd.
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Freedman, D. (2007). Natural selection. New York: Hyperion.
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Gibson, J. P., & Gibson, T. R. (2009). Natural selection. New York: Chelsea House.
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Darwin, C. (2010). On natural selection. Camberwell, Vic: Penguin.
Phys.org, (December 20, 2016). Stabilizing evolutionary forces keep ants strong. Phys.org – Science and Technology News, 2016-12.
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