Natural Selection in Animals

Stephanie Villa, Leidy Luciano, Bertrand Appia, & Shreya Raghavan 

Laboratory 1

Abstract

(Stephanie)

The theory of evolution was developed through the lens of natural selection. Natural selection describes how populations evolve throughout time. Natural selection emphasizes the survival of a particular organism is increased by the ideal traits that have been developed depending on their environment. These ideal traits are presented throughout the variation of genetic traits that cause a mutation. These mutations cause random changes in the DNA that can create portions of a population to better adapt to the environment and survive. Therefore, the evolution of an organism is essential for the overall survival of a species throughout time. 

Introduction

(Stephanie) 

Within this lab, we will examine a mutation of a species and the role of natural selection in the evolution of the species population. Mutations can cause changes in the physical appearance of an organism and in their abilities. These mutations, if favorable, can cause the evolution of a species. Alongside natural selection, these changed aspects can cause a change within the population of a species over time. For instance, if a change is favorable the mutant organisms’ survival rate will increase. Overtime the mutant organism will reproduce and pass down the adaptable aspect to offspring that make up the population. The main objective of this lab is to determine whether the mutant population of a species will surpass the normal population due to the changing environment surrounding the species. Inserting a new predator within an environment and observing the survival rate within a population of normal species and only one mutant will allow us to determine whether the different traits of the mutant animal will be a dominant trait present in the species population over time. 

Methods & Materials 

(Leidy) 

The study was administered, by using a virtual lab conductor that stimulated how different mutations in animals affected their evolution. There were three main mutations to choose from: large body/ long legs, small body/ white fur, and claws for climbing. Per each mutation selected two different conditions were given to select from. These conditions alongside the different mutations determined the survival of the animals in the virtual lab. After selecting a mutation and a condition we would click on the begin mutation button. The virtual lab stimulates what would happen to animals with the two selections made after five generations. A small visual of what happens to the animals during the mutation is given. Afterward, a graph can be derived by clicking on the populate graph button. The graph is then used to compare what happened to the animal population throughout the five generations. The blue line represents the population of animals without the mutation and conditions selected. While the yellow line represents the population of the animals with the mutation. Our group, in particular, was in charge of mutation 3, claws for climbing, and condition A, a new predator.

Results 

(Bertrand)

	Normal	Mutation
Generation	Population	Population
0	50	10
1	43	14
2	38	20
3	30	24
4	21	36
5	14	39

The population of the animals with the mutation allowing them to climb and the normal animals that didn’t have mutations was observed in the simulation with the presence of a new predator in the ecosystem. When looking at the table you can see how the mutants had an incredibly small population compared to the animals with normal traits. The mutant’s population was smaller because they were first introduced into the population with only a few animals exhibiting the trait of claws for climbing. As time passed through each generation you can see the mutant’s population increase while the normal animals’ population decreases. The mutation for climbing helped the animals evade the predator more effectively. Evading the predator allows the mutant population to have more opportunities to reproduce and pass on the trait of having claws for climbing. The normal animals were left without a way to evade the predator. The only options they were left with were simply trying to outrun or hide from the predator. Looking at the table you can see how ineffective it was, this left the normal animals with fewer opportunities to reproduce than the mutants since they were now the predators’ primary food source since they were more accessible. After the third generation, the mutants’ population managed to pass the ‘normals’.   

Discussion 

(Shreya) 

Our hypothesis was correct in that the mutant population ultimately surpassed the normal population due to their ability to climb, which allowed them to evade predators. The theory of natural selection says that organisms that have traits that are best suited to their environment have the highest likelihood of survival. Thus, in the scheme of evolution, where groups of populations evolve, these favorable traits are selected for throughout generations as it offers the best chance of survival. In this simulation, the mutant squirrels had the trait of claws for climbing, versus the normal squirrels without the claws for climbing. When there was a new condition, a new predator, natural selection came into play, and the squirrels with the claws were selected over the normal squirrels. The individuals with no claws to climb were killed off by the new predator, as they had no defense mechanisms. However, those individuals that had claws, and were able to climb up the trees in order to avoid being prey to the new predators, have an evolutionary advantage over the squirrels with no claws, and thus were selected for in the succeeding generations, and five generations later, as shown in figure 2,  eventually resulting in a population with very few normal squirrels and a majority of squirrels with claws. Figure 4, which is a graph of the number of mutant and normal animals per generation, shows this trend. As the number of generations increased, the number of normal squirrels decreased, and the number of mutant squirrels increased in the population, again supporting our hypothesis. 

Conclusion 

(Stephanie) 

In this lab, we learned that the adding of a new predator changes an environment and has an effect on the evolution of a species throughout time. From observations, we learned that the mutant animal was more adaptable to the environment which caused its survival rate to be greater than the normal animal who didn’t possess the trait. Mutations play a role in the evolution of a species because they bring adaptable traits that prolong the survival of a species and are passed down throughout time. Alongside natural selection, the traits of the mutant are put to the test to be either favorable for survival or ineffective. Working together they become factors of whether a trait is effective in increasing the survival rate of a specifies and overtime change the characteristics of the population. 

Figures

(everyone)

Figure 1

Figure 2

Figure 3 

Figure 4