Evolution
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Evidence of Evolution
Evolution is the process of change in living organisms that occurs over time. Although not everyone thinks that organisms evolve, scientists believe that species have developed and become diverse from earlier forms during the history of the earth. The idea of evolution was originally was rejected in Europe because it conflicted with the teachings of the Bible. However, over time, scientists have argued and used evidence to prove the evolution of organisms. One way scientists validate evolution is through fossils. Fossils are remains of plants and animals that date back millions of years ago. In sedentary rocks, scientists can tell the approximate age of a fossil by the layers. Scientists can compare deeper fossils to ones closer to the top to see how they developed and evolved as species to survive.
Evolution is the process of change in living organisms that occurs over time. Although not everyone thinks that organisms evolve, scientists believe that species have developed and become diverse from earlier forms during the history of the earth. The idea of evolution was originally was rejected in Europe because it conflicted with the teachings of the Bible. However, over time, scientists have argued and used evidence to prove the evolution of organisms. One way scientists validate evolution is through fossils. Fossils are remains of plants and animals that date back millions of years ago. In sedentary rocks, scientists can tell the approximate age of a fossil by the layers. Scientists can compare deeper fossils to ones closer to the top to see how they developed and evolved as species to survive.
Change in Allele Frequency
Evolution is the result of change in allele frequency, which is the proportion of a particular allele in the population. Some alleles are more common than others, therefore more individuals will express that trait. There are different factors that can drive a change in allele frequency. Over a long period of time, the change in allele frequency of a population can lead organisms to develop and become better adapted to the environment or fail to keep up, resulting in extinction.
Evolution is the result of change in allele frequency, which is the proportion of a particular allele in the population. Some alleles are more common than others, therefore more individuals will express that trait. There are different factors that can drive a change in allele frequency. Over a long period of time, the change in allele frequency of a population can lead organisms to develop and become better adapted to the environment or fail to keep up, resulting in extinction.
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Mutation:
A change in the sequence of DNA that results in change of the genetic information of an organism is called a mutation. This factor is the only way new alleles are created.When one letter of the nitrogenous bases is altered, it can lead to a change in a whole trait. The new alleles must be heritable, meaning that the mutation must occur in the gametes, and can be either harmful or helpful to the organism. It also may or may not affect the reproductive success. For example, a lamb with five legs instead of four can help it run faster or slow it down depending on if it is mobile.
A change in the sequence of DNA that results in change of the genetic information of an organism is called a mutation. This factor is the only way new alleles are created.When one letter of the nitrogenous bases is altered, it can lead to a change in a whole trait. The new alleles must be heritable, meaning that the mutation must occur in the gametes, and can be either harmful or helpful to the organism. It also may or may not affect the reproductive success. For example, a lamb with five legs instead of four can help it run faster or slow it down depending on if it is mobile.
Some of the types of mutation are insertion, deletion and substitution. Insertion occurs when one or more bases are added to the amino acid sequence, while one or more bases are removed in deletion. On the other hand, the number of bases stays the same in substitution. Instead, a base is replaced by another base.
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Migration:
When a group of individuals move from one population to another, it enables gene flow and creates new allele frequency. There is usually a geographical barrier separating the two populations like mountains or a river. The individuals from the migrant population add their alleles to the population they moved to and exchange the alleles. This increases the variation in the population and allows the gene pool to diversify.
When a group of individuals move from one population to another, it enables gene flow and creates new allele frequency. There is usually a geographical barrier separating the two populations like mountains or a river. The individuals from the migrant population add their alleles to the population they moved to and exchange the alleles. This increases the variation in the population and allows the gene pool to diversify.
Genetic Drift:
Genetic drift is a random movement in allele frequency. One type of genetic drift is the Founder Effect. This is similar to migration in the way that a group of individuals leave the population. However, the difference is that they create a new population instead of joining one. The few individuals breed within the population, creating a different allele frequency. An example of this can be found in Amish people. The Amish founders carried a recessive allele of having six fingers. Because of the small isolated population, the trait spread within the community.
Genetic drift is a random movement in allele frequency. One type of genetic drift is the Founder Effect. This is similar to migration in the way that a group of individuals leave the population. However, the difference is that they create a new population instead of joining one. The few individuals breed within the population, creating a different allele frequency. An example of this can be found in Amish people. The Amish founders carried a recessive allele of having six fingers. Because of the small isolated population, the trait spread within the community.
Another type of genetic drift is Population Bottleneck. In this situation, there is a dramatic decrease in a population caused by a natural disaster or humans. After the event, a few randomly selected individuals will become the foundation of the next generation. This will reduce the variation in the population and specific traits will dominate.
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Natural Selection:
A theory by Charles Darwin described that evolution occurred through survival of the fittest. This means that those best adapted to the environment live to reproduce and pass on their genes. The conditions needed for Natural Selection are:
A theory by Charles Darwin described that evolution occurred through survival of the fittest. This means that those best adapted to the environment live to reproduce and pass on their genes. The conditions needed for Natural Selection are:
- Variation in a trait (ex. tall, short)
- Trait must be heritable and has to be passed on to the offspring
(ex. humans- height, eye color animals- fur color, size) - Differential reproductive success (stronger organisms reproduce)
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Evolution of the Tortoise Beetle
The tortoise beetle is a much more advanced arthropod that has evolved. The first arthropods were marine worms that lived in the ocean during the Cambrian period. They lacked both eyes and antennae. Over time, arthropods traveled onto land and developed exoskeletons (velvet worms). Hexapods, which are insects with six legs like the beetle, further evolved and diverged from the myriapods 400-500 million years ago.
Special Adaptations
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- The Golden Tortoise Beetle changes color from golden metallic to orange with black dots when frightened
- They can change color depending on the moisture/humidity around them because they have a transparent shell that reflects light
- Larvae has spines all around the body and has something called the "anal fork", which is used to hold their feces as a shield
- Adult tortoise beetles have a shell like exterior that protects them from predators, giving them their name
- The shell like exterior are wing covers that protect themselves from predators (they grip onto the leaves so that they can't pulled away by their legs)