The Evolutionary Process

Gene flow is the movement of genetic material from one population to another.

T

Mutations are changes in an organisms DNA affecting its physical and physiological characteristics

T

The sources of genetic variation are mutations, gene flow, and sexual reproduction

T

eye color is an example of genetic variation

T

Natural selection requires _____.

variation, inheritance, differential adaptiveness, differential reproduction

_____ is a source of genetic variation.

- Reproduction - Mutation - Gene flow

Mutation

A change in an organism's DNA affecting its physical and physiological characteristics

Did you know? #1

Although Charles Darwin receives credit for discovering the mechanism of natural selection, Alfred Russel Wallace simultaneously proposed evolutionary theories paralleling Darwin's.

A _____ is a sequence of 3 nucleotides corresponding with a specific amino acid for protein synthesis.

Codon

_____ is a prerequisite for the mechanisms of evolution.

Genetic Variation

Substitution

Exchanges one nitrogenous base for another

A substitution occurs when an extra base pair is added to a DNA sequence.

F

Genetic Variation is the movement of genetic material from one population to another

F

Reproduction is the primary evolutionary process

F

Biodiversity is attributed to evolutionary processes only on a cellular level.

F Biodiversity is attributed to evolutionary processes on every level of biological organization.

A _____ occurs when a small group of individuals from a population breaks off to establish a subcolony.

Founders Effect

_____ is a type of mutation.

Frameshift

The founder effect is an example of _____.

Genetic Drift

Genetic Drift

Genetic drift is the mechanism of evolution in which the allele frequencies of a population change by chance. Genetic drift occurs randomly and does not select for specific alleles. - While genetic drift occurs in all populations, the effects in a small population are stronger. - For example, flipping a coin 1,000 times is more likely to produce a 50-50 head-to-tails ratio than flipping the coin only 10 times. Two examples of genetic drift are the bottleneck effect and the founder effect. The bottleneck effect occurs when population numbers are reduced dramatically due to events such as natural disasters, which can destroy many individuals. - The remaining population may consist of alleles in different frequencies than were present in the original population. - After this event the genetic composition of the random survivors becomes the composition of the entire population. See Figure 3. The founder effect occurs when a small group of individuals breaks off from the larger population to establish a subcolony. - This new colony may not represent the genetic diversity of the original population. - The founder effect is similar to the bottleneck effect except it is due to colonization rather than a catastrophe.

Explore Evolutionary Processes

Genetic variation is attributed to evolutionary processes on every level of biological organization, from cellular molecules to species. Evolution is the process that results in changes to gene frequencies of a population, and successive populations, due to the accumulation of changes in DNA over time. - The mechanisms that can lead to these changes include mutation, migration, genetic drift, and natural selection.

Explore Sources of Genetic Variation

Genetic variation refers to diversity in gene frequencies among individuals or populations. Genetic variation requires a gene pool with multiple alleles for traits, such as eye color. The sources of genetic variation include mutations, gene flow, and sexual reproduction. Mutations are the primary source of genetic variation, and are alterations in an organism's DNA sequencing. Mutations are heritable and affect an organism's genetic makeup. Only some mutations are expressed in an organism's genotype. Gene flow is the movement of genetic material from one population to another. sexual reproduction is the production of offspring, and can introduce new genetic frequencies into a population by combining the genetic material of each parent. Genetic variation is a prerequisite for the mechanisms of evolution. See Figure 1 for an example.

Exercise 1 Evolutionary Process Identification

In this exercise, you will use the Internet to research several given scenarios. You will then determine the evolutionary processes associated with each scenario. You will also use the Internet to research additional examples of the evolutionary processes covered in this lesson. Procedure: Part 1: Process Identification Use the Internet to reserach the scenarios listed in Data Table 1. Determine the evolutionary process- either mutation, migration, genetic drift, or natural selection- associated with each scenario. Be sure to find at least 3 sources confirming your conclusions. Enter your results in Data Table 1. If applicable, determine the specific type of process, i.e. an insertion type mutation, and enter your results in Data Table 1. Part 2: Examples of Evolutionary Processes Use the Internet to research an additional example for each evolutionary process covered in this lesson. Identify each scenario in Data Table 2. Determine the evolutionary process associated with each example and enter your results in Data Table 2. If applicable, determine the specific type of process- i.e. an insertion type mutation- and enter your results in Data Table 2.

Genetic Drift

Mechanism of evolution in which the allele frequencies of a population change from generation to generation, as a result of individuals producing more offspring by chance

Migration

Migration is the movement of a population, group, or individual which may result in the introduction or removal of genetic material from one population to another if interbreeding occurs. - Migration results in the dispersion of gametes and offspring, or the relocations of breeding individuals. There are two types of migration - immigration introduces genetic material to the gene pool - emigration removes genetic material. The result of migration is an increase in genetic variability within a population. - Variability enables populations to respond to environmental changes, and over time, any introduced trait will become part of the population's gene pool. This prevents reproductive barriers from forming, which can lead to speciation.

Natural Selection

Natural selection is the primary mechanism of evolution, resulting in changes to the gene pool of a population and subsequent populations from the sexual reproduction of beneficial traits. - The components required for natural selection to occur are variation, inheritance, an unsustainable rate of population growth, and differential survival and sexual reproduction. Variation describes individuals within a population with different traits, giving them a competitive advantage or disadvantage. - Variations can include size, color, or number of offspring. Inheritance describes the traits that are continuously passed on from parents to offspring, or the traits that are influenced by environmental conditions. An unsustainable rate of population growth describes populations that produce more offspring than resources can support, leading to substantial mortality. Differential survival and reproduction describes the individuals who possess beneficial traits yielding more offspring in an environment with limited resources.

Frameshift

Result of an insertion or deletion causing the message from a gene to no longer translate

Deletion

Results in a section of DNA being removed during replication

Natural Selection

Results in changes to the gene pool of a population and subsequent populations from the reproduction of beneficial traits.

Insertion

Results in extra nucleotides being added into a DNA strand

Research an example of a specific type of evolutionary process not involved in the scenarios described in Exercise 1. List the scenario and briefly describe the specific process

The Galapagos finches are an example of an evolutionary process as their beaks changed. In this scenario, Darwin observed that fruit-eating finches had parrot-like beaks, whereas the insect-eating finches had narrow prying beaks. Darwin concluded that a storm displaced the finches, separating them from their original island, which allowed for the finches to adapt to their food source, which allowed for the change in beak shape. The process that occurred was adaptive radiation meaning a group of organisms is diversified. This happened when the original species of finch had to adapt to a new environment allowing for a competitive living—environment, causing mutations to occur in the finches size, beak shape, song, and feeding behaviors. Expected Answer Polydactyly is a symptom of chrondoectodermal dysplasia, causing extra fingers or toes. This syndrome is found commonly among an Amish community in Pennsylvania. This population formed from a small group of original members. As is the Amish tradition, Amish marry within their own community, limiting the genetic variation entering the population. This scenario is an example of the founder effect, or a form of genetic drift where a small group of individuals breaks off from the larger population to establish a subpopulation.

List and define the four evolutionary processes covered in this lesson.

The evolutionary process results in changes in genetic material for a given population over time: this lesson covered mutations, genetic drift, gene flow, and natural selection. Mutations are the primary source of genetic alteration and variations, which results in changes seen in organisms' DNA. Mutations include substitution, codons, insertions, deletions, frameshift mutations, naturally occurring mutations, and externally influenced mutations. For example, Substitution occurs when one nitrogen base is exchanged for another, which result in codon changes. Codon changes (a sequence of 3 nucleotides) may encode different amino acids, which result in the alteration of protein. Genetic Drift effects the appearance of a gene in a specific (smaller) population; this can allow gene variations to subside, which reduces variability. It's important to note that genetic drift occurs randomly and includes the bottleneck effect and the founder effect. The bottleneck effect is when a population's numbers reduce due to naturally occurring phenom such as a natural disaster like a flood or fire. The founder effect is described as a smaller population of species leaving the broader community, allowing for the creation of subcolonies. Gene Flow or gene migration is the transfer of genes from one population to another, which allows for the introduction or removal of genetic material. Gene flow includes migration, immigration, and emigration. Migration provides a more diversified population due to the dispersion of gametes allowing for the relocation of offspring. Immigration allows for genetic material to be introduced, whereas Emigration allows for the removal of genetic material. Natural selection is the main mechanism for evolution and allows for evolutionary change in a population. Natural selection includes variation, inheritance, unsustainable rate of population growth, and differential survival and reproduction. Variation can include size, color, and the number of offspring for a species allowing for different traits to create a new population with an advantage. Inheritance can be affected by the species-environment, described as traits that are continuously passed down from parents to offspring. An unsustainable rate of population rate is described as a population that produces more offspring than resources can allow for survival. Differential survival and reproduction represent individuals in a population of species that yield beneficial traits for survival when the environment they live in has limited resources.

Migration

The movement of a population, group, or individual resulting in the introduction of genetic material from one population to another

_____ occurs when individuals differ in appearance or behavior.

Variation

Evolution of a species occurs when _____.

The sequencing of an organism's alleles change

Mutation

There are four main types of mutations: substitution, insertion, deletion, and frameshift. A substitution occurs when one nitrogenous base is exchanged for another, as shown in Figure 2. Changes to nitrogenous bases result in codon changes. A codon is a sequence of 3 nucleotides (adenine, thymine, guanine, and cytosine) corresponding with a specific amino acid for protein synthesis. These codon changes may encode different amino acids, altering the protein that is produced. A mutated codon may also result in the originally intended amino acid, causing no effect on the protein produced. A substitution could also result in the formation of a stop codon causing the production of an incomplete protein. Additional mutations include: insertions that result in extra base pairs being added into the DNA strand, and deletions that result in a section of DNA being removed during replication. A frameshift mutation is the result of an insertion or deletion that causes the message from a gene to no longer translate, rendering them useless. See Figure 2 for examples of the four main types of mutations. Mutations can occur from both naturally and externally influenced sources. - Naturally occurring mutations are typically the result of failing to correctly copy DNA from the original sequence during cell division. - Externally influenced mutations may result from chemical or radiation exposure that causes the DNA to degrade beyond repair. - Mutations that occur in reproductive cells may result in significant changes to the genotype and phenotype of offspring. These mutations fuel the process of evolution.

List and describe the specific types of mutations covered in this lesson.

Three types of mutations can include substitution, insertions, and a frameshift mutation. Substitution occurs when one nitrogen base is exchanged for another, which result in codon changes. Codon changes (a sequence of 3 nucleotides) may encode different amino acids, which result in the alteration of protein. Insertion mutations result in an extra base pair being added to a DNA strand. Frameshift is the result of deletion and insertion which causes genetic messages to no longer be processed making them useless.

Anemophily is a type of pollination where pollen is distributed by wind.

True

Natural selection can involve multiple evolutionary mechanisms. For the first scenario presented in Part 1, discuss the evolutionary processes taking place and the effects on the peppered moth coloration.

Upon researching, I found Darwin's Moth or The Peppered Moths is an excellent example of one of the most significant discoveries (natural selection) from Darwin. One evolutionary mechanism that occurs in the Peppered Moths is Genetic mutation. This changed the color variations of the Peppered Moth populations, which include the white, black, and peppered color that appears. When this mutation occurred, the black moth was unable to blend in, which allowed for higher visibility for predators—making the likelihood of them becoming prey higher, allowing for a lower population of the black moths in contrast to the white and peppered moths. With this moth population, the white moth proved to be the preferred color through natural selection. The white moths color allowed for a higher survivability rate as this color allowed for lower visibility to predators. As defined by natural selection, we can assume the reproductive population of the black moths is lower as compared to the white and peppered moths, which allowed for fewer black moths to be born. Upon further research, it's clear that the inherited trait of having a variety of different characteristics (color of moths) impacted their survival rate directly. I did wonder if there was a possibility of this moth population to mutate further, possibly producing black and white or black and peppered moths over time. If this mutation occurred, we could assume the color hybrid could allow for an even larger moth population eradicating the solid colored moths all together.