Unit 8 Reflection

Unit 8 was all about evolution, how all the species, and the earth itself, have changed over time. We learned about what exactly was the definition of evolution and how it was measured. All the alleles that make up genes in population are called the gene pool. The frequency of an allele in the population is called allele frequency. Evolution is measured as a change in allele frequency in the gene pool, so all species are constantly evolving. One allele becomes more or less frequent due to natural selection. Natural selection ultimately ends up choosing the genes in individuals that are more likely to survive and reproduce, therefore, making the population look like the "winners". In the Hunger Games Lab, which was the main lab this unit, we saw the disappearance of stumpys over time. They had undesirable characteristics, and therefore did not get a chance to survive and reproduce. The pinchers, on the other hand, grew more in the population because they had the most desirable characteristic to pick up food (using their thumb and index finger).
Natural selection also works in different ways. Directional selection is when one extreme phenotype is favored.  As we saw in the bird beak lab, the tweezer beaks were favored since they were the most helpful in picking up food and soon the amount of offspring were mostly tweezer beaks. Stabilizing selection is when intermediate phenotypes are favored. Disruptive selection is when two extreme phenotypes are favored. Natural is not the only thing that causes species to evolve. Genetic drifts are random events that suddenly changes the allele frequency. This change may be either good or bad. Gene flow is the movement of alleles from one population to another. Mutations can cause a change in DNA, and if desirable, will become frequent in the population. Sexual selections that improve mating success but not help the organisms survive better.
Speciation is the creation of new species. Species separate when they are reproductively isolated. This means that the two species cannot reproduce and have fertile offspring. Temporal isolation is when they reproduce at different times. Geographic isolation is when they are physically separated. This is a technique often used with dog breeders. Behavioral isolation is when they have different techniques to attract mates.

Link 

The theory of evolution is opposed, but there is evidence to support it. When all organisms are an embryo, they all look very similar. This suggests that we all share a common ancestor. We also have features that helped our ancestors or that they had, such as our tailbone which shows that we used to have tails. Some organisms have same structures with different functions (homologous). Others have different structures with the same function.
The earth's history is longer than anyone can comprehend. Species have been evolving on this planet for billions of years. The timeline has been divided up based on major extinctions and emergence of species.

Link

This unit was relatively easy for me. The only difficult thing is wrapping my head around the scale of the timeline. Also I am not sure exactly how unicellular organisms became multicellular organisms and how those grew into plants, animals etc.
I still have many unanswered questions. Is it possible that if even one event from the past had not occurred then we would not be here? How did species evolve if they were mainly asexually reproducing (bacteria, unicellular)? If there have been several mass extinctions, then is it wrong that we are stopping some species form going extinct? How does "natural selection" choose the better genotypes if each organisms' genotype is randomly assigned?
Going back to the New Years Goals, I have been keeping up quite well. I started studying 3-4 days in advance and I utilize my free time to finish homework if I know I will not get time.

To be more assertive I have tried to be more honest, but kind, to people. I am not aggressive, but sometimes passive aggressive and I try to stop myself whenever I feel that I am being more aggressive. I need to stop being passive in situations where I stay passive to avoid trouble to difficulty in solving the problem.

Geologic Timeline Individual Reflection

The first major event was when cyanobacteria began photosynthesis during the Proterozoic Epoch. Once cyanobacteria began photosynthesis, they put a lot of oxygen into the atmosphere, helping oxygen persist in the atmosphere because it was usually consumed as soon as it was put out. More oxygen lead to a decrease in some bacteria but multicellular algae, and toward the end of the Proterozoic, the first animals started coming up. This was the most critical event in developing life since without large amounts oxygen in the atmosphere, humans would not survive.

The second main event was the extinction at the end of the Paleozoic Era. The mass extinction got rid of 80% of all the species on earth. It affected marine communities the most by far, causing the extinction of most of the marine invertebrates of the time. Some groups survived the Permian mass extinction in greatly diminished numbers, but they never again reached the ecological dominance they once had, allowing another group to dominate the sea. However, this massive loss of life lead to an explosion of life. The new period that began was the time of the dinosaurs. Life was never the same. 

The third main event occurred in the tertiary period. Birds and mammals were began to radiate and flowering plants and insects began to dominate. We know this because the fossils of this time period indicate that. The domination of mammals was the beginning of the evolution of homo sapiens. If mammals began to dominate and grow later or not at all, then humans would probably not be at the stage we are now, or we may not have evolved to be the way we are right now.

The first billion years or so consists of no life on earth.  Life shows up quite late on the timeline. The dinosuars existed on the earth for approx 1/3 of all of its history and were the humans of the Mesozoic Era. The only thing that we have evidence of their existence is fossils. Humans show up only in the last 12,000 years. Im amazed that the earth went so long without life and yet we have changed the earth more than it has probably changed in the past 4.6 billion years. 

We have had a gigantic impact on the earth compared to the amount of time the human race as we know it has existed. All of recorded history does not even make up one second in the clock of the universe. We are already cutting down all the forests, polluting the rivers, and killing off species on a planet that has been around nearly 500 times longer than we have of recorded history. A planet that has taken 4.6 billion years to be made is being destroyed in a few centuries. I think it is far too late to turn back now because these precious things cannot be replaced for a few centuries, and that is long enough for the human race to go extinct. 

I wonder why only our planet evolved the way it did. How do we know that there were not human-like creatures before us? How much longer can the earth sustain us? What event will mark the beginning of a new era or epoch?

Hunger Games Lab

1. In this lab, we went outside to the field, and each of us was assigned a way to pick up "food". There were three different ways to pick up food: using both your wrists, your thumb and index finger, and in between your middle knuckles. This simulated natural selection and competition. When the people that had enough food survived and the others "died", coin flips simulated sex and meiosis. When the coins were in the air, that simulated crossing over and when they were put down together that simulated sex.

2. The pinchers were the best at picking up food. They had a good grip on the food and could stretch their beaks/fingers the furthest apart so they could technically pick up 4 pieces at one time.

3. In this lab we asked the question: Do populations evolve? We found if the gene pool and allele frequency has changed over time, then evolution has occurred. At the beginning of the lab the "A" allele had a frequency of 52% and the "a" allele had a frequency of 48%. They had an almost equal ratio. In the middle of the lab (trial 5) the "A" allele had a frequency of 34% and the "a" allele had a frequency of 66%. At the end of the lab, the "A" allele had a frequency of 28% and the "a" allele had a frequency of 72%. We can see that the "A" allele frequency steadily decreased over time while the "a" allele slowly decreased over time. This means that the population evolved since the allele frequency changed over time.

4. There were many random and non-random things in this lab. Mr. Orre randomly placed the food on the ground and it was random for who was standing closest to the most amount of food. The competitiveness and fitness of the students was also random because that played a role in determining who got the most food.  The places where people stored their food was also random, because some people had big pockets, some had small pockets, and some used their jackets. The flipping of coins and offspring were random. The mate choice was not random. The way people picked up their food was not random since they were assigned a certain way to do it. This affected how well certain species survived or died off. This  could have caused certain alleles to be more dominant because even though the method of picking up food may have been easy, the person may be very slow or have no place to store their food once he/she picked it up.

5. Yes, the results would have been different if the food sizes were larger or smaller. The stumpys would have died off much more slowly if the food sizes were bigger, because then it is easier to pick up. The knucklers would have had a little harder time picking up food. because they cant stretch their fingers further apart then they did with the corks. The pinchers would be better off because they would get a better grip on food. If the size was smaller, then stumpys and knucklers would have died off more rapidly, but pinchers would have grown faster. In nature due to a genetic drift, the size and type of food avaliable may be different. For example, Darwin's finches had smaller beaks because the seeds they ate were small and soft. Later, a drought occurred, and the main type of seed available  was hard and big, so the finches slowly decreased in population size or evolved.

6. Yes there would be a huge difference if there was no incomplete dominance. Every time  knucklers mated they would produce a stumpy. The pinchers would start inbreeding a lot more to preserve their trait. The stumpys would overtake the population but that is not necessarily the best trait because it makes obtaining food difficult.

7. Natural selection causes evolution to occur. Natural selection acts on the phenotypes that seem best suited for the environment by ensuring that only the better traits can mostly survive and reproduce. This changes the allele frequency therefore evolving the population in their genotypes which produce certain suitable phenotypes.

8. Most people did not have a main strategy while obtaining food. It felt a lot similar to "each one for himself". Individuals with the same traits did not try and get together. Some people cheated and grabbed handfuls of food, which could have resulted in errors in the results. People did not mate with who would help them survive better, but rather who would help them reproduce better offspring. The knucklers seemed to mate with the knucklers to give their children a better chance of being a knuckler or pincher rather than a stumpy. Pinchers bred with pinchers because they did not want their children to be a knuckler. It was difficult to tell the mating preferences of the stumpys because they often died before reproducing, but they tried to mate with pinchers to have a knuckler rather than a stumpy. This caused there to be a lot of knucklers in the population quite consistently. These mating choices also played a role in the decreasing number of stumpys. In nature, peacocks have large beautiful feathers to attract mates because strong feathers indicate they are better at obtaining food and the colors are attractive.

9. In evolution, the population as a whole evolves. Individuals cannot evolve since they are stuck with what their parents gave them. Natural selection acts on both the phenotype and genotype. It wants the phenotypes that reproduce and survive better, so to obtain these traits it acts on the genotypes, especially if it is a mutation, that caused the favorable phenotype. It can also act directly on the genotype to get rid of certain genetic diseases.

10. I still have a lot of questions. Could we have evolved into something completely different if a certain event had not happened? What will we evolve into? How exactly do we track evolution and know for sure what changes happened in allele frequency? Why did people reject the theory of evolution? If they rejected it, what did they believe in?

Graph showing change in allele frequency over time 

Everyone runs towards the food (Picture credits to Kimi) 

Bird Beak Lab

Part 1
In this lab, we asked the question "If natural selection occurs in a population, how do changes in selective pressures affect the evolution of that species?" We found that if there are individuals with better traits leave more offspring, then the tweezer beaks will survive and pass on their genes. The tweezer beak produced 18 offspring, which was the most amount of offspring produced by a certain bird in the group. The tweezer's beak was far more accurate to pick up food and it was the easiest to use to pick up food. This lead to the tweezer getting a lot of food/energy so it could produce lots of offspring.

We also found that if the population looks like the winners, then the tweezer beaks will become dominant in the population. The tweezer beak's offspring made up 37% of all of the offspring in the group. The spoon made up 8%, the binder clip chicks made up 20% and the scissor chicks made up 35%. The tweezer chicks are slowly making up a bigger percentage of all of the offspring, because they are the "winners" since they are reproducing the most.

Part 2
In this lab, we asked the question "If natural selection occurs in a population, how do changes in selective pressures affect the evolution of that species?" The tweezer beak collected 7 seed pot plants or approximately 2 chicks in part 1. If the seed pot plants died out, then we will see a slight decrease in the tweezer beak chicks. Our hypothesis was not supported, and in fact there was an increase in tweezer chicks. The tweezer beaks produced 23 chicks in part 2. This is five more offspring than it produced in part 1. This meant that the shortage of food did not negatively affect the tweezer beaks.

Our data was unexpected because shortage in food usually leads to a decrease in energy and offspring, but the tweezer beaks saw an increase in offspring.There could have been some errors. First, this lab required a little bit of practice for the humans who were simulating the beaks, and so they could have gotten much better with using their beaks as the lab progressed. This could have lead to the increase of tweezer chicks in part 2 instead of a decrease, because I became more skilled with picking up other types of food. Second, sometimes everyone "ate" food for different times because we were not aware when the music started and stopped exactly. This would change the amount of offspring by at least 1. Due to these errors, in future experiments I would recommend having everyone rotate which "beak" they used and counting before starting/ stopping the music.

This lab was done to demonstrate Charles Darwin's main observations and conclusions. From this lab, I learned how evolution occurs which helped me understand how there are winners and losers in the population. I also better understand how the gene pool changes. Based on my experience in this lab, I better understand how Darwin's conclusions are the results of evolution.