Geologic Time Line Reflection

  In this project, we worked as a group to create a geological timeline using components creatively to assist in better understanding major events that occurred in the history of the earth. We used 10 meters of register tape and labelled and colored major events for each era, period, and epoch of Earth's history. We used 2mm of register tape for every 1 million years, and it was shocking to see how a lot of the more major events occurred "recently" considering the geologic time scale. Things like human existence seem like a blink of the eye considering  the entire geologic time scale. What I noticed when working on the project, is that not much occurred during the longer, earlier periods, and only simple life forms like bacteria and algae dominated. I already knew from previous lessons about how long the precambrian era was, but actually physically drawing on this scaled timeline really showed me a new point of view.
  3 major events in Earth's history would probably be the rise of oxygen in the atmosphere, the dinosaur extinction, and the splitting of Pangea. As blue-green algae and cyanobacteria photosynthesized, the levels of oxygen on the earth increased immensely during the Precambrian Era. This is extremely important and contributed to the existence of oxygen dependent organisms like ourselves.  The Pangea was a supercontinent that used to be a large mass of land that covered roughly1/3 of the earth. It was broken up during the Mesozoic Era, and it was a big part of Earth's history because it created changes in the climate and atmosphere, and it also gave us all the different continents we have today.  Lastly, the end of the Mesozoic Era marked a mass extinction that wiped out the dinosaurs who previously dominated land on Earth. Earth today would be very different if dinosaurs still roamed the earth.
   Like I mentioned before, human existence is just a blink of an eye in terms of the earth's geologic history. In the considerably "small" amount of time we have been on Earth, we have done some major irreversible damage as a species. Although a lot of major life forms arose in the later epochs of the geologic time line, some other major events are currently occurring. We are in the middle of Earth's 6 mass extinction, and it is predominantly caused by humans. We have caused tremendous change to the Earth and we have caused global temperatures to soar off the charts. As humans, in our small amount of time, we can at least have some respect for our Earth to educate each other and make sure we do not create an end to this timeline. I feel as if it is our responsibility to take care of our Earth which is so often taken for granted.
  I wonder how much we can decrease our carbon footprint as far as we've come. Right now I'm typing on a computer that was shipped most likely using fossil fuels. I'm sitting with the light on, and hopefully the power plant where the electricity is coming from is not coal-based and rather runs on wind or water power. I know I can just sit here and rant all day about global warming and how we can never get everyone to stop living their lives, because we have become such a fast paced society so focused on work and life, but we never stop to realize where we actually are, or where everything we use is actually coming from. For now we can all take small steps to reduce our waste and reduce our carbon footprint just by being educated and aware about the issue.





Works Cited:
Geologic Timeline. Digital image. MBMG. N.p., n.d. Web. 20 Apr. 2017. <http://mbmg.mtech.edu/graphics/time-line.gif>.

Unit 8 Reflection

   This unit was all about evolution and the different ways it is studied. We first learned about artificial selection, or breeding for desired traits, which is used by humans for work and food purposes. We also talked about natural selection and Charles Darwin's observations and conclusions. He observed that:

1. All sexually reproducing species have high genetic variation
2. Traits are inherited from parents to offspring
3. All species are capable of producing more offspring than the environment can support
4. Competition is severe because of limited food and resources

   There are two types of competition, inter-competition that occurs between two different species and intra-competition that occurs between two of the same species.
   Darwin's first conclusion stated that there are "winners and losers" as better traits leave more offspring. His second conclusion stated that the "winners" were the population because beneficial traits become more common. Darwin's ideas on natural selection were displayed in our Hunger Games Lab. 
  The gene pool was also discussed, as it is the total of all alleles in a population for one trait. Allele frequency is calculated by dividing the total number of one allele by the total number of all the alleles. If allele frequency has changed over time, that indicates that the population has evolved. Lethal alleles, if recessive, can be hidden in heterozygotes, yet beneficial if conditions change. 
   Speciation was also a major topic we learned about this unit. It is the process of 2 or more species evolving from one existing species. It is caused by reproductive isolation, either temporal(timing), behavioral(courtship/attraction), or geographical(physical barriers).
   We also talked about how descendants of common ancestors have common traits. Embryology shows common ancestry. The patterns of speciation are as follows: Punctuated equilibrium, which occurs rapidly, or gradualism, which occurs slowly. Evo-devo is the study of the process of evolutionary development in multicellular organisms. Hox genes are relatively unchanged overtime(highly conservative), and they are responsible for turning on other genes during development. Vestigial structures are also known as evolutionary left-overs.




  Fossils are formed in these four steps:

1. Organism dies
2. Organism is covered in ash, sediment, or clay
3. Pressure and chemicals cause organism to become rock
4. Hard parts fossilize better than soft parts(fossil bias)

  Index fossils with known time periods are used for comparison. Relative dating is using the placement of fossils with sediment layers to estimate time periods of existence. Homologous structures are same structures, different functions. Analogous structures are different structures, same function. Convergent evolution is the process where unrelated organisms evolve similar structures.
  Natural selection occurs in 3 ways:

1. Directional selection-favors phenotype at one extreme
2. Stabilizing selection-favors intermediate/medium phenotype
3. Disruptive selection-favors phenotypes at both extremes

   Genetic drift is when a random event drastically changes a population and its allele frequency changes as a result. After genetic drift, genetic variation decreases, making populations less resistant to change. Genetic drift changes allele frequency due to chance alone by this random event.

Types of change include:

1. Genetic Drift-random event drastically changes population
2. Gene flow-move of alleles from one population to another
3. Sexual Selection-traits that improve mating success chosen rather than for survival
4. Natural selection-traits chosen advantageous for survival

   Lastly, the history of life was discussed in terms of the geologic time scale. Adaptive radiation is the rapid speciation from a common ancestor. First was the pre-cambrian era, then the paleozoic era which included the cambrian, ordovician, silurian, devonian, carboniferous, and permian periods. Then the mesozoic era occurred and it was known as the age of the reptiles, with the triassic, jurassic, and cretaceous periods. Then the cenozoic era occurred where mammals dominate, and the periods include tertiary(paleogene and neogene)and then quaternary. We are currently in the holocene era, but only a blink of an eye in terms of the earth's history.

  As for my self growth, I feel as if I am more assertive and I am speaking up for myself more. I am no longer hesitant to ask for something, because now I know that the worst possible thing that can happen is for someone to say no. I feel like I am more assertive socially, but personally I feel like I can improve and be more assertive with myself. I need to start being more assertive with myself so I can get work done when I need to to avoid procrastination.

Works Cited

A., Jonathan. Evolution. Digital image. Study Blue. N.p., 24 Mar. 2015. Web. 11 Apr. 2017.

Gradualism vs. Punctuated Equilibria. Digital image. American Museum of Natural History. N.p., n.d. Web. 11 Apr. 2017. <http://www.amnh.org/learn/resources/images/evolution_W4E3_punctuated.jpg>.

How Fossils Are Formed. Digital image. In. N.p., n.d. Web. 11 Apr. 2017. <https://image.slidesharecdn.com/fossilsppt-120502044843-phpapp01/95/fossils-ppt-6-728.jpg?cb=1335934187>.