Evolution: Natural Selection - Lance Small
Curriculum Expectations
C1.2 Evaluate the possible impact of an environmental change on natural selection and on the vulnerability of species (e.g., adaptation to environmental changes can affect reproductive success of an organism)
C2.1 use appropriate terminology related to evolution, including, but not limited to: extinction, natural selection, phylogeny, speciation, niche, mutation, mimicry, and adaptation
C3.1 explain the fundamental theory of evolution, using the evolutionary mechanism of natural selection to illustrate the process of biological change over time
C3.4 describe some evolutionary mechanisms (e.g., natural selection, artificial selection, sexual selection, genetic variation, genetic drift, biotechnology), and explain how they affect the evolutionary development and extinction of various species (e.g., Darwin’s finches, giraffes, pandas)
C2.1 use appropriate terminology related to evolution, including, but not limited to: extinction, natural selection, phylogeny, speciation, niche, mutation, mimicry, and adaptation
C3.1 explain the fundamental theory of evolution, using the evolutionary mechanism of natural selection to illustrate the process of biological change over time
C3.4 describe some evolutionary mechanisms (e.g., natural selection, artificial selection, sexual selection, genetic variation, genetic drift, biotechnology), and explain how they affect the evolutionary development and extinction of various species (e.g., Darwin’s finches, giraffes, pandas)
Learning Goals
Students will:
- Distinguish between different evolutionary mechanisms
- Define the theory of natural selection and provide both real life examples and hypothetical examples
- Analyze a species of creatures and determine the order in which evolution has occurred
- Experience how natural section affects different species of creatures
- Provide examples of how human interactions have prompted natural selection
- Develop a thorough understanding of evolution
Content Section
Overview of Natural Selection
Natural selection is the gradual, non-random process by which biological traits become either more or less common in a population as a function of differential reproduction of their organisms. It is a key process of evolution. The term "natural selection" was made popular by Charles Darwin who meant for it to be compared with artificial selection.
Theory of Natural Selection 1
1. More individuals are produced each generation that can survive.
2. Phenotypic variation exists among individuals and the variation is heritable.
3. Those individuals with heritable traits better suited to the environment will survive.
4. When reproductive isolation occurs new species will form.
Fitness
Natural selection is the gradual, non-random process by which biological traits become either more or less common in a population as a function of differential reproduction of their organisms. It is a key process of evolution. The term "natural selection" was made popular by Charles Darwin who meant for it to be compared with artificial selection.
Theory of Natural Selection 1
1. More individuals are produced each generation that can survive.
2. Phenotypic variation exists among individuals and the variation is heritable.
3. Those individuals with heritable traits better suited to the environment will survive.
4. When reproductive isolation occurs new species will form.
Fitness
- The concept of fitness is central to natural selection
- Individuals that are more "fit" have better potential for survival - "survival of the fittest"
- Modern evolutionary theory defines fitness not by how long an organism lives, but by how successful it is at reproducing
- If an organism lives half as long as others of its species, but has twice as many offspring surviving to adulthood, its genes will become more common in the adult population of the next generation
Types of Selection
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Stabilizing Selection
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Directional Selection
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Disruptive Selection
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Sexual Selection
Example of Natural Selection 2
Darwin's grand idea of evolution by natural selection is relatively simple but often misunderstood. To find out how it works, imagine a population of beetles:
1. There is variation in traits. For example, some beetles are green and some are brown.
2. There is differential reproduction. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do.
3. There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis.
4. End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown.
- Sexual selection is a “special case” of natural selection.
- Sexual selection acts on an organism's ability to obtain or successfully copulate with a mate.
- Selection makes many organisms go to extreme lengths for sex: peacocks maintain elaborate tails, elephant seals fight over territories, fruit flies perform dances, and some species deliver persuasive gifts.
Example of Natural Selection 2
Darwin's grand idea of evolution by natural selection is relatively simple but often misunderstood. To find out how it works, imagine a population of beetles:
1. There is variation in traits. For example, some beetles are green and some are brown.
2. There is differential reproduction. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do.
3. There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis.
4. End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown.
Student Activities
Class Dojo Monsters
The students will develop a basic understanding of the theory of natural selection using custom-made monsters. This is a great introductory activity to get the students hooked. Students will each create a custom monster which will be tested against the environmental conditions of Plant Dojo.
Teachers go to the Class Dojo website to create a teacher login, then you can print off student codes which will allow student access to your class.
To download the activity PowerPoint, click here.
Natural Selection Activity Package
This activity package offers seven different activities which are related to evolution and the theory of natural selection. For each activity there is background information for the teacher, student handout and solutions to this handout.
Topics covered in this activity package:
Of Mice & Moths
This webpage provides a material list, activity procedures, and post activity assessment questions. Students show how genetic variation of offspring contributes to population control in an environment and that natural selection ensures that those who are best adapted to their surroundings survive to reproduce.
The students will develop a basic understanding of the theory of natural selection using custom-made monsters. This is a great introductory activity to get the students hooked. Students will each create a custom monster which will be tested against the environmental conditions of Plant Dojo.
Teachers go to the Class Dojo website to create a teacher login, then you can print off student codes which will allow student access to your class.
To download the activity PowerPoint, click here.
Natural Selection Activity Package
This activity package offers seven different activities which are related to evolution and the theory of natural selection. For each activity there is background information for the teacher, student handout and solutions to this handout.
Topics covered in this activity package:
- Theory of natural selection
- Genetic drift
- Mutation
- Survival of the fittest
- Cloning
Of Mice & Moths
This webpage provides a material list, activity procedures, and post activity assessment questions. Students show how genetic variation of offspring contributes to population control in an environment and that natural selection ensures that those who are best adapted to their surroundings survive to reproduce.
Online Resources
This video is great at giving a humourous, but informative overview of the process of evolution.
Assessment Tools
Click here for a unit test on evolution. There are varying questions types and it is in Microsoft word format, so it can be edited.
For an online multiple choice quiz, click here.
For an online multiple choice quiz, click here.
Glossary
Adaption - any alteration in the structure or function of an organism or any of its parts that results from natural selection and by which the organism becomes better fitted to survive and multiply in its environment.
Allele - any of several forms of a gene, usually arising through mutation, that are responsible for hereditary variation.
Artificial selection - a process in the breeding of animals and in the cultivation of plants by which the breeder chooses to perpetuate only those forms having certain desirable inheritable characteristics.
Evolution - change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift.
Mimicry - the close external resemblance of an organism, the mimic, to some different organism, the model, such that the mimic benefits from the mistaken identity, as seeming to be unpalatable or harmful.
Mutation - a sudden departure from the parent type in one or more heritable characteristics, caused by a change in a gene or a chromosome.
Niche - the position or function of an organism in a community of plants and animals.
Phenotype - the appearance of an organism resulting from the interaction of the genotype and the environment.
Phylogeny - the evolutionary history of a group of organisms, especially as depicted in a family tree.
Sexual selection - a special type of natural selection in which the sexes acquire distinct forms either because the members of one sex choose mates with particular features or because in the competition for mates among the members of one sex only those with certain traits succeed.
Speciation - the formation of new species as a result of geographic, physiological, anatomical, or behavioral factors that prevent previously interbreeding populations from breeding with each other.
Theory of natural selection - the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.
Allele - any of several forms of a gene, usually arising through mutation, that are responsible for hereditary variation.
Artificial selection - a process in the breeding of animals and in the cultivation of plants by which the breeder chooses to perpetuate only those forms having certain desirable inheritable characteristics.
Evolution - change in the gene pool of a population from generation to generation by such processes as mutation, natural selection, and genetic drift.
Mimicry - the close external resemblance of an organism, the mimic, to some different organism, the model, such that the mimic benefits from the mistaken identity, as seeming to be unpalatable or harmful.
Mutation - a sudden departure from the parent type in one or more heritable characteristics, caused by a change in a gene or a chromosome.
Niche - the position or function of an organism in a community of plants and animals.
Phenotype - the appearance of an organism resulting from the interaction of the genotype and the environment.
Phylogeny - the evolutionary history of a group of organisms, especially as depicted in a family tree.
Sexual selection - a special type of natural selection in which the sexes acquire distinct forms either because the members of one sex choose mates with particular features or because in the competition for mates among the members of one sex only those with certain traits succeed.
Speciation - the formation of new species as a result of geographic, physiological, anatomical, or behavioral factors that prevent previously interbreeding populations from breeding with each other.
Theory of natural selection - the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.
References
1. McClean, P. (1997). Darwin's Theory of Evolution by Natural Selection. In Population and Evolution Dynamics. Retrieved 17/02/2013, from http://www.ndsu.edu/pubweb/~mcclean/plsc431/popgen/popgen5.htm.
2. Unknown Author. (2011). Natural Selection . In Understanding Evolution . Retrieved 17/02/2013, from http://evolution.berkeley.edu/evolibrary/article/evo_25.
3. Unknown Author. (2012). Sexual Selection. In Evolution 101. Retrieved 17/02/2013, from http://evolution.berkeley.edu/evosite/evo101/IIIE3Sexualselection.shtml.
4. Unknown Author. (2013). Natural Selection. In Sparknotes. Retrieved 17/02/2013, from http://www.sparknotes.com/biology/evolution/naturalselection/section1.html.
2. Unknown Author. (2011). Natural Selection . In Understanding Evolution . Retrieved 17/02/2013, from http://evolution.berkeley.edu/evolibrary/article/evo_25.
3. Unknown Author. (2012). Sexual Selection. In Evolution 101. Retrieved 17/02/2013, from http://evolution.berkeley.edu/evosite/evo101/IIIE3Sexualselection.shtml.
4. Unknown Author. (2013). Natural Selection. In Sparknotes. Retrieved 17/02/2013, from http://www.sparknotes.com/biology/evolution/naturalselection/section1.html.