In class, we have just finished Unit 8, constant change, or evolution. We first learned about artificial selection. This is where humans breed two organisms and manipulate their traits to suite their own purposes. For example, over time, collies were bred for speed and agility for use in sheep herding. Great Danes were bred for their size and strength for use as guard dogs. The list goes on and on.
The next vodcast was about what Darwin discovered. Darwin traveled as a naturalist on the HMS Beagle. He traveled all around the world collecting fossils and specimens. He noticed a few things. First, all sexually reproducing organisms have high genetic variation. He also noticed that traits were inherited from parents to offspring. All species are able to produce more offspring than nature can handle. He finally noticed that competition is stiff. He concluded that since individuals with better traits survive better and reproduce more than other individuals. In other words, there are winners and losers. His second conclusion was that over time, populations tend to look like those who reproduce more. In other words, populations tend to look like winners. Natural selection is the process of weeding out traits that do not help an organism survive.
The following vodcast was about the gene pool. The gene pool is the total amount of alleles in a population. Gene pools change over time as a result of natural selection. Allele frequency is how common a certain allele is. To determine this, add up the total of all alleles and the total for each type of allele. For each type, divide by the total. Natural selection acts on the phenotype because those with the best phenotype reproduce more. Lethal alleles still stick around in those who are heterozygous. Those alleles may become useful if the environment drastically changes.
The next vodcast was about speciation. Speciation is the process in which two poplations gradually become more and more different, eventually becoming two different species. The cause of this is reproductive isolation. If populations are split, they eventually will not be able to reproduce with each other. One type of speciation is behavioral isolation. This is caused when two population have different mating rituals. The next type is geographical isolation, and it is caused when a natural barrier such as a river or mountain range separate two different populations. The last type of speciation is temporal isolation. This is caused when timing prevents reproduction between two populations. All species have a common ancestor. The closer the common ancestor is, the more related the species are. There are two competing theories for speciation. Gradualism says that speciation occurs slowly over time, while punctured equilibrium says that new species arise suddenly.
For those of you who do not believe in evolution, there is a lot of evidence that says evolution actually happened. During the first stages of the embryo, many animals look remarkably the same, which suggests a common ancestor. In addition, many organisms have evolutionary leftovers that were needed for our ancestors but not anymore. We also have fossil evidence. Fossils form when an organism is covered in silt and is put under enormous pressure. Fossils tell us that organisms have changed overtime. There is also homologous structures, same structures but different function. Contrasting are analogous structures, same function but different use. Finally, convergent evolution is the process in which unrelated organism evolve similar and analogous structures.
There are three types of change. Directional selection is where one extreme phenotype is favored. Stabilizing selection favors the intermediate phenotype. Disruptive selection favors both extreme phenotypes. There are many types of change. Genetic drift is when a catastrophic event drastically changes a population. Those who survive do so by luck. Gene flow involves the moving of alleles from one population to the other. Mutations produce new variation that natural selection acts on. Sexual selection selects for traits that improve mating success, but do not help organisms survive. Natural selection selects for traits advantageous for survival.
The last vodast was about the history of life. Chemical and physical processes could have produced very simple cells. There have been experiment that have shown that abiotic synthesis of organic molecules is possible. RNA molecules could have been produced from simple molecules, and DNA could have come from RNA. Earth's timescale is huge. There have been 5 mass extinctions and many periods of adaptive radiation. Earth has changed dramatically and humans are just a blink of an eye in Earth's history.
I want to learn more about evolution. I want to know more about real world examples of evolution. I am also intrigued about the idea of intelligent design. I am still curious on how life on Earth formed. It is one of the great mysteries.
In the Unit 7 Reflection, I learned more about my conflict style. I am trying to become more assertive. I have done this by asking more questions when I am confused. In addition, I have tried to become more of a leader in my group projects. I think that I am becoming more assertive.
The next vodcast was about what Darwin discovered. Darwin traveled as a naturalist on the HMS Beagle. He traveled all around the world collecting fossils and specimens. He noticed a few things. First, all sexually reproducing organisms have high genetic variation. He also noticed that traits were inherited from parents to offspring. All species are able to produce more offspring than nature can handle. He finally noticed that competition is stiff. He concluded that since individuals with better traits survive better and reproduce more than other individuals. In other words, there are winners and losers. His second conclusion was that over time, populations tend to look like those who reproduce more. In other words, populations tend to look like winners. Natural selection is the process of weeding out traits that do not help an organism survive.
The following vodcast was about the gene pool. The gene pool is the total amount of alleles in a population. Gene pools change over time as a result of natural selection. Allele frequency is how common a certain allele is. To determine this, add up the total of all alleles and the total for each type of allele. For each type, divide by the total. Natural selection acts on the phenotype because those with the best phenotype reproduce more. Lethal alleles still stick around in those who are heterozygous. Those alleles may become useful if the environment drastically changes.
The next vodcast was about speciation. Speciation is the process in which two poplations gradually become more and more different, eventually becoming two different species. The cause of this is reproductive isolation. If populations are split, they eventually will not be able to reproduce with each other. One type of speciation is behavioral isolation. This is caused when two population have different mating rituals. The next type is geographical isolation, and it is caused when a natural barrier such as a river or mountain range separate two different populations. The last type of speciation is temporal isolation. This is caused when timing prevents reproduction between two populations. All species have a common ancestor. The closer the common ancestor is, the more related the species are. There are two competing theories for speciation. Gradualism says that speciation occurs slowly over time, while punctured equilibrium says that new species arise suddenly.
For those of you who do not believe in evolution, there is a lot of evidence that says evolution actually happened. During the first stages of the embryo, many animals look remarkably the same, which suggests a common ancestor. In addition, many organisms have evolutionary leftovers that were needed for our ancestors but not anymore. We also have fossil evidence. Fossils form when an organism is covered in silt and is put under enormous pressure. Fossils tell us that organisms have changed overtime. There is also homologous structures, same structures but different function. Contrasting are analogous structures, same function but different use. Finally, convergent evolution is the process in which unrelated organism evolve similar and analogous structures.
There are three types of change. Directional selection is where one extreme phenotype is favored. Stabilizing selection favors the intermediate phenotype. Disruptive selection favors both extreme phenotypes. There are many types of change. Genetic drift is when a catastrophic event drastically changes a population. Those who survive do so by luck. Gene flow involves the moving of alleles from one population to the other. Mutations produce new variation that natural selection acts on. Sexual selection selects for traits that improve mating success, but do not help organisms survive. Natural selection selects for traits advantageous for survival.
The last vodast was about the history of life. Chemical and physical processes could have produced very simple cells. There have been experiment that have shown that abiotic synthesis of organic molecules is possible. RNA molecules could have been produced from simple molecules, and DNA could have come from RNA. Earth's timescale is huge. There have been 5 mass extinctions and many periods of adaptive radiation. Earth has changed dramatically and humans are just a blink of an eye in Earth's history.
I want to learn more about evolution. I want to know more about real world examples of evolution. I am also intrigued about the idea of intelligent design. I am still curious on how life on Earth formed. It is one of the great mysteries.
In the Unit 7 Reflection, I learned more about my conflict style. I am trying to become more assertive. I have done this by asking more questions when I am confused. In addition, I have tried to become more of a leader in my group projects. I think that I am becoming more assertive.
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| Embryology |
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| Experiment that showed abiotic synthesis of organic molecules is possible |
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