Abstract
Natural selection is the gradual process where biological traits are changed to become either more prominent or uncommon in a given population. Individuals who have certain trait variations may have better survival chances and having higher reproduction rate compared with those who lack such trait variations. This favors such a population to thrive more compared with others and eventually result to a new population that has evolved. This experiment aimed to demonstrate the power of a small advantage in causing evolution as a result of natural selection. The number of the unicorns in the population where all the colors had the same fitness was almost constant with an average of 25 unicorns per generation. The number of the unicorns in the population where all the colors had the unequal fitness increased as generations increased attaining a level of 70 unicorns by the 50th generation. The experiment successfully demonstrated the power of a small advantage in causing evolution as a result of natural selection. The red unicorns increased in number when having a red color was considered to be more fit than having the other colors.
Introduction
Natural selection refers to the gradual process through which biological traits are changed becoming either more prominent or uncommon in a given population due to the effect of the traits that are inherited and their interaction with the environment. Natural selection represents a crucial mechanism in the process evolution (Andersson, 1994). The term natural selection was publicized by Charles Darwin as a comparison with the artificial selection or the commonly known selective breeding.
Within any group of organisms in any given population, there are variations within the members making up the population. This occurs partially due to the random mutations that take place in the genomic material of the individuals, which can then be passed to their offspring. Through the life, the genome in an individual continues to have an interaction with the environment resulting in variations in the different traits, in the genome. The environments surrounding the genome such as the populations, other cells, the molecular biology, species, other individuals, and the abiotic environment are some of the areas that may be affected resulting in an effect on the genome (Andersson, 1994).
People who have certain trait variations may have better survival chances and having higher reproduction rate compared with those who lack such trait variations. This favors such a population to thrive more compared with others and eventually result to a new population that has evolved. In addition, factors that may affect the success of reproduction may also affect the chances of survival leading to a phenomenon referred to as sexual selection. Although natural selection works on changing the phenotypes, or those characteristics that are observable in an organism, there are possibilities of the genetic basis describing the phenotypes becoming more common in the population. Overtime, the selection results in a population that has specific traits that enable them to thrive well in a particular environment and to some extents resulting to new species emerging (Andersson, 1994).
Natural selection, therefore, enables evolution to occur within a given population favoring the organisms that are best fit to survive in the environment. In contrast to the artificial selection where the members of a population who express certain traits are specifically chosen by human, natural selection does not make intentional choices. The selection occurs automatically and, therefore, the best or the appropriate species are selected. In artificial selection, the results are sometimes far from the desired ones due to proper interaction with the environment (Andersson, 1994).
The process of natural selection occurs among those individuals making the population and the differences created have no effect on the survival rate of the selected individuals. Some changes may, however, increase survival chances of the individuals in the population. For example, in a population with green and brown beetles, the green beetles may be eaten more by the birds than the brown beetles. This causes the brown beetle to reproduce more due to their number than the green beetles. The adult brown beetles thus have a higher survival rate compared to the green beetles. This results in the brown coloration if the beetles being more favored and this increases their number in the population. Eventually, the population will be composed of the brown beetles. There are, however, some incidents where a trade-off between current reproduction and survival. Those that are able to reproduce more may dominate those who are living longer of their reproduction rate is low (Andersson, 1994).
This experiment aimed to demonstrate the power of a small advantage in causing evolution as a result of natural selection.
Methods
In order to measure the power of even a small advantage in causing evolution, an experiment was set up using a population in which one color was only slightly better at survival and reproduction than the other. In order to do this, a population where everyone was equally fit was first set up where the species that were either blue or red in color had equal chances of survival. The population was run for 50 generations or until only one color was left. The number of red unicorns for each generation was recorded, and the experiment repeated for a total of 10 trials. Once the 10 runs were complete, the average number of the red unicorns over all the trials for the 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 generations was calculated and the data recorded. The parameters that were used for the two experiments were as shown in Table 1 below.
The process was repeated using the population parameters that red had only a 5% advantage over the other two colors.
Results
The average number of red unicorns for the 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 generations was calculated and the data recorded in Table 2 below. The number of the unicorns in the population where all the colors had the same fitness was almost constant with an average of 25 unicorns per generation. The number of the unicorns in the population where all the colors had the unequal fitness increased as generations increased attaining a level of 70 unicorns by the 50th generation. The red unicorns did not attain a 100 mark by the fiftieth generation, and the highest number was 96 unicorns after 43 generations in the population where Red had only a 5% advantage over the other two colors.
The average number of the unicorns recorded for the 11 generations was used to plot a graph of average unicorns against generations as shown in Figure 1. The average number of the unicorns increased as the generations increased in the population where all the colors had equal fitness. In the population where Red had only a 5% advantage over the other two colors, the number of the red unicorns was almost constant in all generations.
Figure 1: The relationship between the average number of red unicorns and generations
Discussion
This experiment aimed to demonstrate the power of a small advantage in causing evolution as a result of natural selection. From the results obtained, the population where all different colored unicorns had an equal level of fitness did not favor the increase in number of the red unicorns. The unicorns were the same in all the generations up to the 50th generation. This means that the red unicorns did not have any unique traits that would have made then better survivors in their environment compared to the other two colors.
On the other hand, being red colored gave the red unicorns a better chance of survival compared to the other two colored unicorns. The environment in this population favored the unicorns that were red colored, and this enhance their expansion. The process of natural selection that occurred in this population selected the red unicorns leaving behind the other two kinds of unicorns. This probably made them able to evade predators in a better was while the other unicorns were being eliminated. This resulted in the red unicorns having a better chance of reproducing more increasing their number in the following generation. Continuing this process for a period of 50 generations resulted in the number of the red unicorns outweighing the number of the other unicorns. Continuing the process further would have resulted into a population that is composed of red unicorns only. Although there are some incidents where a trade-off between current reproduction and survival occur (Andersson, 1994), such a situation is evident that it did not happen in the population where the red unicorns were more fit than the others. The red unicorns were able to reproduce at a high rate and thus increasing their population size.
In conclusion, the experiment successfully demonstrated the power of a small advantage in causing evolution as a result of natural selection. The red unicorns increased in number when having a red color was considered to be more fit than having the other colors.
Reference List
Andersson, M. B. (1994). Sexual Selection. New Jersey: Princeton University Press.
