Dottus Predation Lab Report

The Effects of Predation as a Selection Pressure

Introduction

Predation occurs towards organisms who have distinguishable traits such as color or certain behaviors that makes them stand out among other adapted organisms (e.g., Mader, 2016). During this experiment, the colored dots were used to represent the phenotypes of the organisms Dottus Variengatus. The null hypothesis tested states that the phenotypes of the Dottus Variengatus have no effect on the numbers of each phenotype selected by the predator. Predators might have certain routines when preying, which is beneficial for organisms with cryptic or intermediate phenotypes because they are better adapted to the environment, meaning they will be more likely to survive (Willink, García-Rodríguez,

The starting population of the experiment contained 100 organisms that had 10 different Dottus Variengatus phenotypes. A multicolored-city board was used to simulate the environment where these organisms lived. To perform the experiment, groups of three were formed. The first member had to act as a new predator of the population, the second member was assigned to randomly disperse the colored dots on the board, help keep count of the consumed dots, and collect materials at the end of the experiment. The third member had to collect the prey from the predator, and help keep count until 25 dots were collected. The predator was not allowed to see where the dots were placed by the second member. The predator had to turn around to select the first dot observed give it to the third member of the group and continue doing this procedure until 25 dots were counted by the second member. The depended variable of this experiment was the number of times each dot was chosen. The controlled variables were the number of dots

After calculating the probability levels for the Chi square values, the sum was 17.8. The value fell in the range of low probability due to chance. Both, Table 9.7 and Table 9.8 rejected the null hypothesis of the experiment.

Discussion

The colored dots were used as a representation of the different phenotypes of the organism Dottus Variengatus. The starting population in the experiment contained 100 organisms of Dottus Variengatus. The results of both parts of the experiment rejected the null hypothesis tested. The Dottus variegatus individuals experienced negative selection effects by predators based on their bright and distinctive phenotypes that made them stand out among the rest of the population. Individuals with lighter colors represented the adapted individuals which experienced positive selection pressure. These individuals were benefited by predation because they survived and could continue to pass their alleles and contribute to the gene pool of the future population. The Chi square gave a statistical analysis comparison between the results of predation occurring because of selective pressure or predation occurring by chance alone. The result of the Chi square analysis showed a low probability of predation due to chance, showing again that the phenotypes of organisms affect their predation possibilities. Majority of the data proved that some organisms