To conduct the experiment, the Evobeaker(r), a computer simulation program called “How the Guppy Got its Spots” (Simbio Virtual Labs (r) was used (Biology 112, 2017,).
The experiment consisted of five locations: Upper West Stream and Lower West Streams, Upper East Stream and Lower East Streams, Meir Creek, with and without predators (Rivulus Cichlid A, Cichlid B), a holding cooler, and three tanks.
Simulations were conducted for four to eight generations before and after the removal and transplantation of predators.
Each simulation involved 15 males being randomly selected and their spot brightness recorded on a scale of 0-20.
The simulations were repeated 21 times. Results were visualized using histograms. Relevant two-sample tests were also used.
We tested the hypothesis that male spot light is determined by adult predator risk (AH1) and found that a decrease or an increase in predation risk could lead to a decrease or increase in the average male spot brightness over time. Male spot brightness was measured before and after 1000 days of the addition of a predator to Upper East Stream (Cichlid A), and after 1000 days of the removal of a prey (Cichlid A).
We tested the hypothesis that male spot lightness is determined by sexual selection (AH2). The average male spot brightness increased over time in a population without adult predators (P2): Male spot brightness was measured 800 days after 15 dull males (brightness score =7) were placed in a predator-free tank.
We tested the hypothesis that male spot light is determined by geographic location (AH3). The average spot brightness of males who are transplanted to a new area would be similar to that of their original location (P3). Male spot brightness was measured in the Upper West Stream before all fish were removed from Upper West Stream, and then all of the Lower East Stream fish were transplanted to the Upper West Stream.
1000 days later, male spot brightness was measured in the Upper West Stream.
We also used P1 to P3 to test the hypotheses of male spot brightness being determined by predation risks, sexual selection, and geographic location (AH4). If any of these predictions is true, then AH4 would support. However, AH5 would not be supported if none of them are true.
Charles Darwin proposed a mechanism that would justify descent with modification in his theory about evolution.
This theory states that if a population of organisms displays inheritance, variation, and differential reproductive success, there is a good chance that its composition changes from one generation to the next (Laland, et al. 2014).
Guppies (Poeciliareticulata), are aquarium fish with a distinctive pattern.
Although wild males aren’t extravagantly decorated, they can still be stunning.
They sport spots, stripes, and splashes in a variety of bright colours, including blue, yellow, orange, and black (Kodric Brown, 1985).
John Endler, an evolutionary biologist who was a pioneer in evolutionary biology, studied the bizarre colouful patterns of wild Trinidad guppies in the 1970s. He was puzzled by the differences among these fishes.
Deacon and Magurran (2016) noted that male guppies who lived in one pool had bright orange and blue spots on their sides, while those living downstream only had small dots in the tails.
Additionally, there were differences in the distributions of predators for guppy guppies.
Endler conducted the research with the hypothesis in mind that predators living in aquatic systems could be responsible for the differences among the populations.
This hypothesis was based on the observation that guppy who lived in a stream with predatory Cichlids had fewer spots than guppies that were living with Rivulus (Endler 1980).
This laboratory work was designed to challenge learners to create a study that would allow for documentation of evolution through natural selection in nature.
This was done to conduct field explorations on wild guppies in order to evaluate variation among males within a variety of wild populations.
John Endler’s definitive study of natural selection in guppies is the basis for the EvoBeaker simulations.
This research was done to assess the variation between guppy males from different populations.
According to the study, predators can significantly reduce the brightness of the male spot.
Alternately, the average brightness in the male spot rose significantly after predators were removed from the stream.
This first hypothesis corresponds to the fact that male spot brightness is determined by adult predation (AH1)
As a fact, the prediction that an increase or decrease in predation risk will result in a reduction or elevation of average brightness of male spots with time (P1) has been confirmed.
Similar results were observed when males and females were introduced to predator-free tanks. This led to a significant increase in the average brightness for male spots in the end.
The second hypothesis, which explains why male spots are brighter by sexually selective (AH2), was also accepted.
It was proven that the prediction that male spots brightness will increase over time in a population without adult predators (P2) is true.
The average spot brightness in male guppies was not significantly different between before and after transplanting.
The average brightness of spots in males of Lower East Stream following transplantation to Upper West Stream, and thereby removing males from the Upper West Stream that were previously there, showed a significant difference.
Geographically locating (AH3) did not support the hypothesis that spot brightness could be determined.
The prediction that the average brightness in spot would be the same in new residents of a similar area (P3) was false.
Based on the combined risk of predation and sexually selecting, the fourth hypotheses was that spot brightness could be determined in males by locating geographically (AH4).
AH4 was supported because two of the three predictions were correct.
The study supports the theory of natural Selection, and more specifically the sexual selection.
Sexual selection refers to a type of natural selection in which certain organisms produce offsprings that are better than theirs so that they have higher chances of being selected for mating (West Emberhard et. al., 2014).
Guppies are unable to exist without a partner, so they have adopted the sexual selection theory.
This struggle between male guppies to possess females results in a lack of offspring.
The evolutionary pressures force male guppies towards being brighter to attract females (Wilson and al., 2014).
The chances that a female guppy will choose him to be her preferred mate would increase if he is brighter (Hooker and al., 2016).
The evolutionary pressure to hide in water bodies with high predator risk is to do so.
In such cases, the priority is to stay alive and not reproduce. This is why body spots are not distinguished.
These results provided valuable evidence that long-standing models of sexchromosome catalysis can be trusted, suggesting that there is both sexual selection and sexual conflict in the evolution of genomes.
Therefore, it can be concluded that spots in guppies are a result Darwin’s natural selection theory.
It supports the theory that sexual selection is supported.
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