Unit 8 Reflection

The essential theme of this unit was evolution. Evolution is the gradual change of a species over time to be best adapted to reproduce and survive in their environment. Natural selection and artificial selection are two factors that can lead to evolution. Natural selection is a process of weeding out traits in a population that do not help individuals survive, leaving traits that are neutral or do not help an individual survive. Natural selection occurs without any human interference. The conclusion of this is that populations evolve over time, not individuals. On the other hand, artificial selection occurs when humans select traits from a population's variation that they want, and only mate individuals with those traits. An example of this is if a farmer wants to breed for the biggest chickens so he can get the most meat to sell. He can achieve this by only selecting the biggest chickens to mate. By doing this, eventually the farmer's population of chickens will all evolve to be big because of artificial selection.

Charles Darwin had two conclusions about evolution. The first conclusion is that there are losers and winners in evolution. The individuals whose inherited traits help them survive better and reproduce more tend to leave more offspring than other individuals. The second conclusion is that populations look like the winners. This is true because the individuals with the better traits are the ones who are reproducing, while the losers are not reproducing because of their inferior traits. Speciation was another topic in this unit. Speciation is the rise of two or more species from one existing species. Speciation is caused by reproductive isolation. Reproductive isolation is when a population is split into two, and eventually the two populations can not reproduce with each other because now they are too genetically different to reproduce. The three causes of speciation are behavioral isolation, geographic isolation, and temporal isolation. Behavioral isolation is caused by changes in mating behaviors or occupying different niches. Geographic isolation is when a barrier divides a population into two or more groups. An example of this is if a highway is built in the middle of a population. Temporal isolation is when timing prevents reproduction between populations. An example of this is if one population likes to mate in spring when another prefers to mate in fall.

Another main topic of  this unit was the origin of life. It is hypothesized that life formed on Earth by chemical and physical processes which may have produced very simple cells through a few stages. Amino acids also may have come from meteorites, which could have served as building blocks for life on earth. A subtopic of this is the geologic time scale. All history is broken into four eras. The Precambrian Era, the Paleozoic Era, the Mesozoic Era, and the Cenozoic Era. Then, these eras are subdivided into many different periods.

I would like to learn more about the dinosaurs. They have always fascinated me because of their sheer size and power. I have many unanswered questions concerning them. Could we ever genetically engineer them back into existence? If so, how would they interact with us humans? I wonder if a world with humans and dinosaurs coexisting could ever be a reality.

In unit 7, we watched a video on tips to become more assertive. I ranked as assertive however there are still things that I can work on. One tip that I have tried to work on is to use more "I" statements instead of "you" statements. I feel that "I" statements help me be more assertive while not sounding as annoying as I would if I use a "you" statement.

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