June 2nd

Discussion questions


Jun 2

1. What does Behe mean by a structure that is irreducible complex?

What Behe seems to be saying is that the cell is so complex and so specifically "designed" that if one piece of it were to be removed, and you were able to test it by removing a piece, then it would not be able to function.

2. Is the mammalian ear irreducibly complex? Why?

According to the text, there is debate about whether the workings of the inner ear is irreducibly complex or not, because the construct of the ear can be evolutionary explained rather than have just occurred. Further, before the parts were complete, they still functioned and served in certain ways. For instance, the lower jaw still functioned for chewing while still allowing the mammal to hear. This disregards the concepts of irreducibly complex because before the whole was complete, the parts still functioned.

3. Behe claims that the eukaryotic cilium as an irreducibly complex structure, arguing that the 9+2 pattern of microtubules is essential for the cilium to beat. Test this hypothesis scientifically.

Figure 5.2 shows that although the 9.2 standard is most common, it does not mean that other arrangements are nonfunctional. 3+0 flagellum is fully functional without the microtubules center, which is evident in the fly Monarthropalpus buxi. This proves that although the eukaryotic cilium is complex, it is not irreducibly complex without the central microtubules.

4. Explain how blood clotting evolved.

This is one system that Behe suggests is irreducibly complex because without one part the whole system would not work. In order to prevent blood loss, many mammals with a closed-circulatory system have clotting abilities: "clot-makers" (fibrinogen) makes up about three percent of protein in blood plasma. The clot-makers get sticky when clots form, and the Factor X steps are necessary to continue the process. This complex step suggests that it did not evolve.

May 10

Carnell and Price, in review

1. What hook does the author use to capture your attention?

Carnell and Price created a fun story that really intrigued me. My group and I are going to adapt the story idea in which the narrative follows kids in a museum that go through all the controversial aspects of T. Rex.

2. How could you adapt this hook in your own case study?

As mentioned above my group and I will be using a narrative with a museum theme. I think this will draw our audience in because it will be a comprehensible yet fun reading.

3. I completed Activity 2 Global Warming:
- For changes in average temperature, I added all the magnitudes of change of each of the ten cities listed, then divided that number by 10 (10 cities listed) to get the overall average temperature: 1.1 F
- Climate is the average, long-term weather of a particular region. For instance, deserts are known to be dry and hot.
-Weather is the day-to-day atmospheric activity of a place, such as rain to sunshine during a week in Seattle.
-Weather conditions that range from hot to cold throughout regions is considered Climate Variability.
-When climates throughout the globe change in temperature, such as cold regions becoming warm while hot regions decrease in temperature, this can be identified as Global Climate Change.
-Global cooling is the overall decrease in surface temperature of the Earth.
-On the other end, Global Warming is the overall increase in surface temperature of the Earth.

4. How is the case study a model for the one you are writing? What do you want to emulate? What do you want to change?

The case study is a significant model for my group because we want to do a story that travels through each chapter while staying interrelated. The challenge for us is what order we want to place the chapters, while maintaining that "hook." We do not need to make changes, thus far, because we have not yet formulated the story. We will have a meeting next week to discuss our narrative, etc.

Signor-Lipps Effect, Wednesday May 5

1. Ever ride the bus all the way to the end of the line? And have you noticed how the bus begins to empty out as you approach the final destination? And that sometimes, when you reach that final destination there’s still a gaggle (albeit a small gaggle) of people getting off? Use this metaphor to explain the Signor-Lipps Effect. As usual, your explanation should be good enough for anyone on campus to understand!

In effort to explain the Signor-Lipps Effect, the bus example on the lab handout provides a useful way to apply it. According to Signor-Lipps, mass extinction is immediate but it can look gradual in the fossil records. In regards to the bus trip, we can look at extinction as every person getting of the bus at each stop (species going extinct). On the final stop, the remaining people (species) exit the bus and no more people remain (catastrophic extinction). Though all the people remaining are gone, that does not mean people were not getting off the bus prior to the last stop. In reference to the fossil records, an animal may have gone extinct, but not in a catastrophic extinction (final bus stop). Species may have been going extinct throughout time (through several bus stops) before reaching a final extinction. Signor-Lipps present the challenge in being able to distinguish the difference in gradual extinction and catastrophic extinction in fossil records.

2. Dinosaurs went extinct at the Cretaceous-Tertiary boundary, but our earliest interpretations were that some groups went extinct well before then. Use the Signor-Lipps Effect to resolve this paradox.

Naturally species go extinct all the time. In regards to the Cretaceous-Tertiary period when animals went extinct, species were going extinct before that. In the Signor-Lipps explanation, diversity declined before the Cretaceous-Tertiary mass extinction but it can be difficult to compare the actual diversity from the apparent diversity. Gaps in fossil records suggests many things about the extinction process, and there are ways to test the hypotheses but it can often be biased (hence the title). However, environmental changes, climate changes, and natural selection are strong evidences that support species extinction before the Cretaceous-Tertiary mass extinction.


3. Write a detailed caption for the graph you made for the worksheet called “Figure 3”. Make sure you explain what each of the curves means, and why each curve has a different shape. You may want to refer to the captions in Signor and Lipps (1982) as a guide for the amount of detail I want.

The different lines in the graph represent diversity: apparent diversity, actual diversity. The blue curve represents apparent diversity which is what we see based on what is covered from the fossil record. The red and green curves represent the actual diversity in which extinction looks gradual. The green curve is the most constant looking line, but then all three curves show a severe drop-off when it reaches around 10 mya. Overall the graph is visually presenting the relationship of gradual diversity from catastrophic diversity before a mass extinction.
.
4. Given the fact that we need to consider the S-L Effect, how can we distinguish between a catastrophic mass extinction and a gradual mass extinction in the fossil record?

To be able to distinguish gradual mass extinction from catastrophic mass extinction from the fossil record we would have to look at apparent diversity from actual diversity. It is difficult to be certain about the differences, however, because the curves can be altered. Some species, for instance, may not have a good record. Or a species may have been going extinct before the mass extinction, but the fossil range may not be consistent. This can make it difficult to put a date on when the fossilized species became extinct.

Signor-Lipps, ZImmer

Discussion questions


May 3

Lab handout

1. What is the main point of Signor and Lipps 1982?
How to look at and understand the difference between actual diversity and apparent diversity.
2. What have you learned from the title of this paper?
I have learned that samples from the gradual and catastrophic extinctions can look similar, so if researching for either there is a good chance of bias.
3. Explain what the vertical axes mean on all three graphs in Figure 2 of Signor and Lipps 1982. The vertical axes demonstrate the time and type of diversity.
4. What do you think Signor and Lipps mean when they question whether the fossil record is to “be accepted at face value” (291)? By this I believe they mean whether the evidence demonstrates the apparent divesity in the fossil record (gradual diversity).
5. What do Signor and Lipps mean by “random truncation of ranges” (292)? This means last time that a species can be preserved.

Zimmer 2010, Radiations and extinctions (excerpt)

1. What hook does the author use to capture your attention? Again, Zimmer uses good images that pertain to the subject. Figure 10.13 for instance, helps the reader to graphically see the dramatic differences in extinctions.


2. How could you adapt this hook in your own case study? We can utilize images that can illustrate what we are trying to explain to our audience, such as the physical structure of T. Rex's leg muscle that show why it was unlikely that the dino could not run fast.

3. When was the biggest mass extinction in the history of animals? What do we call this extinction event? What caused it?
According to the chart on page 231, the biggest mass extinction, also called Permian-Triassic extinctions, occurred 250 mya.
4. Which species seem to be most robust to extinction? Why? According to the article, it seems that birds would have been least vulnerable to extinction because they have the advantage of flying. They probably had better navigational an transportation abilities, likely to outrun sudden impacts in their environment.
5. What’s the difference between mass extinctions and background extinctions? Background extinctions occur as when a species goes extinct overtime. Mass extinction happens when species die out simultaneously along with the ecosystem.

6. Zimmer warns us that global climate change is one drastic consequence of increasing the amount of carbon dioxide in the atmosphere. What is the other? Humans. Humans have contributed to evolutionary forces such as deforestation, increases in carbon dioxide, and climate change that can lead to extinction.

7. How could you use Figure 10.15 as a hook for capturing the attention of your audience in the introduction of a case study? Images like this can have a greater effect on the viewer to comprehend the subject. In regards to T. Rex, we can use a visual aid like 10.15 that can show whether it was a scavenger or hunter. I don't how we can make it a graph but we can demonstrate the scavenger point of view from the hunter point of view and explain how each may be possible.

April 28th Discussion Questions

Discussion questions Apr 28

http://ublib.buffalo.edu/libraries/projects/cases/alien/alien_evolution.html

1. What hook does the author use to capture your attention?
The author takes the reader somewhere they have never been: another planet.

2. How could you adapt this hook in your own case study?
We can create a story or image of a creature similar to T. Rex and describe that chronicles his daily life. We can ask the audience what this organism resembles and what they think it evolved from based on its stature.

3. Answer the questions at the end of Part I and Part II of this case study.
You have two days before you and your colleagues must decide the fate of this planet and the hundreds of people who are waiting to re-colonize it. Before you come to any conclusions, however, you need to find out exactly what happened on this planet, why it happened, and what the future possibilities are. Start with sources on Earth's Late Precambrian, aka "Vendian" or "Ediacaran" period, and the Cambrian period (543 to 510 million years ago). By the time you return to class to solve this case, you will need to know:

• What was the Late Pre-Cambrian environments like on Earth? it probably somewhat like mars. Gases prevailed, litle oxygen, oceans probably looked very different from how we see them today.
• What were the Ediacaran organisms like and how were they adapted to their environment? Ediacaran organisms were probably small and varied in size and appearance.
  
• How is Earth's Precambrian similar to P-L5's initial environment and organisms? They describe rapid changes occurring such as water levels; there was fresh air; descriptions of small organisms that showed signs of predation. These are all similar images to Earth's Precambrian era.
• What was the "Cambrian Explosion"? Cambrian explosion involved the rapid evolution of organisms about 530 mya.
  
• How did the environment and organisms change and adapt during the "Cambrian Explosion"? Radiation adaptability allowed for growing variations and diversity of organisms.
• What causes lead into the "Cambrian Explosion"? Chemical and physical changes: higher levels of oxygen in the atmosphere and ocean; retreat of glaciers.
  
• Could any of those Earth conditions have been mimicked on P-L5? How? Yes, because the description of their experience resemble the Cambrian changes that occurred on earth. It seems they landed during the explosion.
  
• Assuming that this alien planet was going through an Alien "Cambrian Explosion" that mimicked Earth, what do you think will happen next? They will start to see variations in animals, and greener environments because PSN can take place.
  
  

Zimmer 2010, Lighting the Cambrian fuse

1. What hook does the author use to capture your attention?
The hook the author appears to be using is by challenging the reader’s knowledge about when animals bloomed: Was it really in the Cambrian era that animals became rapidly abundant? Rather they suggest that animals evolved.

2. How could you adapt this hook in your own case study?
On the subject of T. Rex, it can be a useful hook to challenge the audience’s idea of how fast he really ran.

3. Compare Zimmer’s hook to the one Tobias used in “Alien Explosion” in a table. Both hooks are useful for different reasons. Which approach do you prefer for your case study? Why?

• Zimmer is more informative in his introduction, in which he lays out the basic facts of the Cambrian era and potential causes.
• "Alien Evolution" creates a story about the Cambrian explosion: he invites the reader to use their imagination by using descriptions of what it might have looked liked in the Cambrian period.
• I would like to use both hooks in my case study because I think they are simultaneously imperative to capture the attention of the audience. I have to assume that my audience knows nothing about my study so utilizing these methods will work to make the topic cohesive while making it adventurous.
  

4. What is a phylogeny? (you’ll probably have to look the word up on the Internet)
According to wikipedia, phylogeny is the study of organisms and their relatedness to ancestors/descendants. This is used to classify diversity among organisms, Taxonomy.

5. Over what time frame did the Cambrian Explosion occur?
According to the Zimmer, the Cambrian explosion occurred around 530 mya. This was determined based on the study of particular fossils.

6. Why was the Cambrian Explosion so remarkable?
This was an extraordinary event because it demonstrates rapid animal evolution largely due to adaptive radiation. The evolution resulted in greater variation and diversity among species.

7. Outline some of the triggers that might have led to the Cambrian Explosion.

• glacial retreats
• increase in oxygen levels in oceans and atmosphere
• chemical changes in oceans

Monday April 26th

Mitch Leslie 2009

1. What hook does the author use to capture your attention?
What captures my attention is the question in the introduction: imagine the world without photosynthesis? This is a simple and intriguing way for the writer to speak directly to the reader. Also the use of pictures is always a a great way to maintain the reader's attention.

2. How could you adapt this hook in your own case study?
Starting off the presentation with a question is a great way to involve the audience: I think it will get them to think about the subject our group will discuss and it may generate more questions.

3. Let's start with the basics. What is photosynthesis?
Photosynthesis occurs in plant organisms when energy from allows them to that in carbon dioxide and convert it in to chemical energy (sugars, carbohydrates). This I have learned from class lectures in biology and ecology.

4. How does Photosynthesis make the earth livable for our ecosystem?
The oxygen produced from early photosynthesizers assisted in developing the ozone layer, as well as multicellular species.

5. What chemical was the basis of the earliest photosynthesizing microbes? of most photosynthesizing organisms alive today?
It appears to me that the basis of the earliest photosynthesizing microbes was hydrogen sulfide. Today, photosynthesis relies on carbon dioxide and water.

6. What role does chlorophyll play in photosynthesis?
While it explains why most plants are green, Chlorophyll has other major roles in the process of photosynthesis. According to the article, photosynthetic organisms combine their chlorophyll to create to systems: photosystem I uses light energy to make ATP and NADPH molecules that convert it to food energy (sugars); photosystem II extracts electrons from water, releasing oxygen into the atmosphere.

7. What was the greatest oxidation event? How do we recognize it in the fossil record?
The GOE was believed to have occured 2.4 billion years ago when oxygen levels greatly increased in the atmosphere. This can be detected in sedimentary rocks: the quantities of sulfur isotopes indicate that oxygen was scarce in the time before GOE. But further research of fossils shows that photosynthesis may have occured earlier than detected. Fossil discoveries in Australia, for example, are 3.2 billion years old but they contain no sulfur which may indicate that photosynthetic microbes used water for energy, according to the article.

Zimmer 2009b, Eukaryotes

1. What hook does the author use to capture your attention?
Again, this author uses images that go along with the reading. The introductory paragraph involves the "you" factor in which the author compares the reader with the content of the article: you have something in common with toadstool.

2. How could you adapt this hook in your own case study?
Our group can use this sort of wow-factor in our presentation by telling the audience what they have to with our case study. You can run faster than T-rex, for instance.

3. What are eukaryotes?
Eukaryotes allowed for multicellular life. They contain a nucleus and are made up of mitochondria and other elements. Organisms like plants and animals are Eukaryotes.

4. What are the mitochondria? How did they evolve?
Mitochondria provide cell energy, ATP molecules, and they can duplicate their DNA. There are theories that they evolved from bacteria cells because mitochondria genes resemble genes of bacteria.

5. What is the hydrogen hypothesis?
According to the article, the hydrogen hypothesis developed by Muller and Martin of the University of Dusseldorf suggests that mitochondrian came from endosymbionts.

6. Briefly compare the three domain hypothesis to the eocyte hypothesis.
The three-domain hypothesis divides the cells into three branches: bacteria, archaea, and eukaryote. This suggests that eukaryote is from arhcaea. However, eocyte hypothesis is favored because there is stronger evidence that eukaryote is from bacteria.

April 21, Wednesday

Discussion questions
Apr 21
Lab Handout
Define each of the variables in this equation.
P:
P­0:
l:
t:
Zimmer 2010, Radioactive clocks
1. What is the different between 12C, 13C and 14C? Which is the most unstable? What is the half-life of 14C?
Carbon-12 is stable and carbon-13 are stable, in which they are easier for organisms to absorb, and this can be seen in old sedimentary rocks (class lecture). Carbon-14, however, is unstable; it decays fast (class lecture).
2. What are some other radiometric decay systems (besides carbon-14) that are useful for determining the ages of events in Earth’s history?
According to Zimmer, the radioactive isotopes, strontium and rubidium, are some ways to measure the age of rocks. Once lava hardens, for example, the strontium levels within the rock remain and no more can enter. The different levels of each isotope can then be measured by calculating its radioactive elements.
3. Why don’t stable elements have half-lives?
4. Write a short dialogue between you and a 12-year old friend explaining Figure 3.1
5. How do we calculate the absolute of fossils?

Two-Pound Dino Discovered!

By Shannon Connant

In the fall of 2009, Royal Society Publishing released its recent discovery of what is considered to be the smallest dinosaur yet to be found. At two pounds and 30 inches long, the Fruitadens haagarorum sets the record as the smallest animal of the Ornithischians group. What makes this finding even more intriguing is that it increases our understanding in the variation of size in dinosaurs, and what that has to do with their evolutionary history. These findings are highly significant for the study of the evolution of ornithischians because it furthers the insight in an area that is not well understood.

Because of its small size, it is considered that the fruitadens haargarorum had an omnivorous diet, consisting mostly of bugs and probably some plants. Furthermore, it is the first smallest-known heterodontosaurid ornithischian (Butler, 2009, Ornithischian dinosaur) animal to be found representing the late Jurassic era, during the mid-Mesozoic period (class lecture). Even more intriguing, this fossil was found in Colorado, making it the first discovered heterodontosaurid in Northwest America.

Studies show that the Fruitadens were bipedal and designed to run. Extensive dental research indicates that the they had the ability to replace teeth while they were young. This is not common among the heterodontosaurid group (Butler, 2009, Ornithischian dinosaur).

While browsing through the science section (paleontology section) of the New York Times, I came across the article of the Fruitadens haagarorum. Henry Fountain, of The New York Times, presents the Fruitadens discovery in a very short, precise article. His information covers where the animal was discovered, what dinosaur group it belongs to, what period it had lived, and a few biological descriptions of the organism. Though his article releases a more comprehensive story of this discovery, it does not provide scientific details like the original article. Proceedings of the Royal Society released the initial article that covers many observations and research of the Fruitadens haagarorum, from the period it lived to a full dental exam.

I searched for the original scientific article using the library guide on the course catalyst. The article appeared immediately after I entered "Fruitadens haagarorum" in the search engine. After close comparison, it appears to me that while the newspaper article by Fountain provides a basic outline of this discovery, it does not emphasize the importance of this discovery in the evolutionary history of ornithischians. But Fountains research is reliable. He sites the finding of the original article and mentions one of the co-authors of it, Dr. Chiappe, several times. I was able to confirm those citations.

The scientific article had several sources it used along with many citations. Their information appeared informative rather than biased, mostly because they discussed the diagnoses of their findings and what that changes for ornithischian evolution. However, the article is from a strictly scientific publication, so it seems biased from that point of view. As for the newspaper article, it seemed more biased because information in the news is considered to be newsworthy. So I felt that this finding was significant since it was addressed in a popular news form. The headline, for instance says that "Two-Pound Dinosaur Holds North American Record": There is a sense of bias here in that the findings were in North America, making it a significant because of where it was located. Another thing to consider is the role of gatekeeper, in which publishers intend to leave out certain information. This can be applied for both the scientific article and newspaper article.

Although the scientific article is objective, there may be biases because it is directed towards the field of palaeoecology, in effort to further understand heterodontosaurids. Nevertheless, this information demonstrates the significance of fossils: though they fill in the gaps of the history of earth, it shows how much we do not know.

URL for New York Times article: http://www.nytimes.com/2009/10/27obdino.html?_r=1&pagewanted=print

URL for origianl scientific article: http://rspb.royalsocietypublishing.org.offcampus.lib.washington.edu/content/277/1680/375.full?sid=69924c58-293c-4caf-aa01-46a79b715c33#sec-1

Preservation Lab April 14th

Preservation Lab


(Remaining eight questions)


1. It may seem intuitively obvious that a slimy little worm is not going to have a good fossil record. But intuition is not good enough for scientists. Explain why it probably won't fossilize using at least three lines of evidence.

Although really soft, sensitive organisms can fossilize when the conditions are just right, more often than not a slimy little worm will not preserve for several reasons based on evidence:

A. They get eaten by predators after they die.

B. They get eaten by predators while still alive. This is evident by the holes in shells, for example, created by predators attempting to eat the organism inside.

C. Sediments do not cover the dead organism in time for it to fossilize.


2. Do shelled organisms that live on top of other shelled organisms increase or reduce their chances of preservation? Explain.

Based on observation, it appears that shelled organisms clumped together would increase their chances of preservation: As mentioned in class (class lecture), shells, or filter feeders, face various directions to take in food. So when they die, it seems more likely that as sediments mold in and out of the shells it would keep the shells together as they were. On the other hand, if the shells were separated before they were preserved I think that they would more likely break apart and dissolve.


3. Why do you think most fossils of birds are from lakes?

Water, especially muddy shores, seem to be ideal conditions for organisms to fossilize. When a bird dies on the shore of a lake, for example, most likely it's wet. This allows sediments to quickly stick to the bird and build up overtime.

4. How do the processes in special preservation differ from the processes in normal preservation?

Fossilization can take place when all the necessary conditions occur. These chance events can result in different types of fossilization.

In normal preservation, organisms are typically eaten by bacteria or other predators but their vertebrae or shell remain and fossilize. Special preservation, however, occurs when the tissue of an organism can be observed in the fossil (class lecture). Such events can happen when a worm, for instance, is immediately covered by sediments upon its death. According to Wikipedia (http://en.wikipedia.org/wiki/Fossil), soft organisms can preserve in areas that are low in oxygen and its chances of decaying are low. But these results are rare and exceptional.

5. What is time-averaging?

According to the class lecture, time-averaging is a tool to measure the span of time an organism populated an area. This is based on many factors, but one way to understand this process is to look at the example of the helmet shells. Fossil remains of a particular species that dominate a specific layer in sediment rock is one possible way to determine the average time the species existed. However, there can be errors in these observations. It is important though to recognize that any fossil has some time averaging.

6. Write a caption for the figure below, explaining how it illustrates time-averaging.

Figure B seems to be representing the sequence of the shells as having existed separately, whereas Figure A shows the different shells overlapping. But I do not understand what the author means by completeness and over-completeness in the context of time-averaging.

7. Compare the magnitude of time-averaging in a varve to time-averaging along the continental shelf where most fossilization occurs.

8. What was the coolest thing you learned in this lab? Why was it cool?

Several things about this lab were cool, but was particularly intrigued by seeing actual fossils and applying what I have learned thus far about them. Further, understanding how the holes occur in shells was neat: were they signs of predation? Did they already have a hole? This was certainly a thought-provoking lab that made me realize the complexities of fossilization.

Discussion Questions April 12th

Discussion questions
Apr 12
What Darwin never knew (online NOVA documentary at http://www.pbs.org/wgbh/nova/beta/evolution/darwin-never-knew.html)
Please note that you can also read the transcript for this documentary; a link to the transcript is available at the same URL.

1. What are some of the recent discoveries that give us insight into how the diversity of life evolved?
Darwin’s observations helped us to understand that diversity in species is a result of change. Just like humans, animals vary in looks even if they are of the same species (I.e. finches). These changes may occur from environmental conditions: Natural Selection. The Galapagos islands, for instance, varied in seed sizes which made finches develop different beak sizes depending on what island they populated.

2. Present some of the developmental evidence for Darwin’s Tree of Life.
According to Darwin’s Tree of Life, all species are connected. Humans, for example, are descendants of fish in which during the development of the human embryo it appears to have gills in one of the phases before birth. These gill-like parts, however, turn into the inner ear of a human while remaining gills to a fish.

3. Part of Darwin’s Theory of natural selection is the idea that different individuals within the same species compete against each other. Explain how this competition led to evolutionary change in:

(1) The Galapagos finches: As mentioned earlier, the Galapagos islands varied in environmental conditions. Seed sizes were different on each island, and in order for a finch to survive, its’ beak size had to adapt to the force that was required to consume the seed depending on the island a finch populated.

(2) Pocket mice in the Pinacarte Desert: Two mice of the same family have evolved different appearances as a means of survival. Eruptions from ancient volcanoes changed parts of desert which means for the mice to survive it will have to change as well. The lighter mouse is camouflaged to lighter brown areas of the desert, which helps it to hide from predators such as owls and coyotes. Where the dark lava remains, mice have developed darker coats to avoid being captured by predators.

4. Give a couple of examples of single mutations that we can identify in particular genes that have proven to be very beneficial.
The Colobus monkey had a mutation in gene that enabled it to see in color: it can distinguish healthy red leaves from old green leaves.
A mutation in an Antarctic fish produces a sort of antifreeze in its blood to survive in freezing waters.

5. Why is it so surprising that humans only have about 23,000 genes?
Humans typically place themselves on high level in the animal kingdom, but the genes show that humans don’t require many genes to be made., according to Olivia Judson. Some of our main genes are similar to other animals.

6. What does the “switch” that Sean Carroll found in fruit flies do?
It allows some fruit flies to have spots and others to not have any spots appear. The gene oversees the details of where the spots will appear on the fruit fly or not.

7. Why do Kinglsey and Schluter think they’ll find the same switch sticklebacks as in manatees, even though the rear fins were lost at completely different times in these lineages?
There findings suggest a pattern of unevenness. Traces of discovered bones resemble the bone structure of manatees today which may explain the evolution of this observation.

8. The fact that Hox genes control the development of fins in paddlefish suggests that the evolutionary transition of fins to limbs wasn’t all that dramatic. Explain.
These Hox genes demand simple changes/ mutations for such differences to occur. Much like the “switch,” the transition of fins to limbs is relatively short.

9. Hansell Stedman found a mutation in the human genome that should lead to muscle problems. But it turns out this mutation has benefited us? Why and how?
This muscle ends ups working to create the muscles that allow us to chew and close the jaw. Unlike apes, however, humans chew with a fraction of the force of ape. Our skulls can expand allowing our brains to grow.

10. Where are most of the genetic differences between humans and chimps located? (i.e., what kind of DNA?)
The differences between the humans and chimps are not in the genes, but they are in the “switches.”: pieces of DNA that turn genes on or off.

McGee, April 7

Discussion questions
Apr 7
McGhee 1984

Compare preserving food to preserving fossils. Use at least three examples from McGhee to form the basis of your comparisons.

1. According to McGee, the first important step in controlling the storage of fruits and vegetables is to maintain them under ideal temperatures and conditions. Humidity, for example, must be relatively higher in refrigerators to slow down the moisture loss of produce. On the other hand, low humidity would be necessary to preserve fossils.

2. Increasing the sugar content is an effective way to preserve food, and can be done in a variety of ways. Gelling, for instance, can make the food harden with the outside material, making it firmer while it dehydrates. Fossils, depending on what kind it is, may not require this form of preservation as it may already be without moisture.

3. McGee’s demonstration of freezing food can partly explain how fossils discovered from layers of ice and sediments came to be in that condition. It makes sense that the process of freezing foods probably has a similar effect on organisms--the respiratory process is stopped. McGee shares, however, that produce can be affected by freezing damage. Can the same be done to fossils?

Discussion Questions April 5

Zimmer 2009a, Origin of Life


1. What hook does the author use to captor your attention? Carl Zimmer begins with Charles Darwin’s short perspective on how life begin. As a tool to capture the audience, I think this is effective by drawing on historical data to present day theories. But it also begins with a discussion that most people ponder: the origin of life.
2. How could you adapt this hook in your own case study? Introducing the case study with a question that is controversial and widespread will be a hook.
3. What is RNA (specifically mRNA, for those of you who have some background in this area)? Why is it essential for using the genetic code? RNA is ribonucleic acid is a single-strand molecule similar to DNA. MRNA is a messenger ribonucleic acid molecule that acts as a template for protein synthesis. The genetic code of transporting the DNA into proteins is identical to RNA.
4. What is the RNA world hypothesis? The hypothesis is that the origin of life may have started with RNA which can be traced with the present day RNA.
5. Why was lightening so essential to the origin of life? Zimmer uses Cleaves’ interpretations in which lightening was a potent source in the development of organic compounds in the beginning of earth. Sparks may have created more amino acids, for instance.
6. What ideas does Zimmer present on how cells may have originated? Zimmer suggests that protocells in temperatures in the 100 degrees C range assisted them to obtain nucleotides and develop RNA in lower temps, and this pattern of heat allowed RNA to replicate fast.
7. Do we have any conclusive evidence to support hypotheses on how life originated? The evidence of the experiments suggests many possibilities to the origin of life, but I do not think they are conclusive. As Zimmer mentions, cells are ever-evolving which suggests that we may not be certain about how cells developed and functioned in the beginning of earth. Experiments will always discover new possibilities.





Zimmer 2010, What the rock say

1. What hook does the author use to captor your attention? It starts with a story of Abigail and her hike to observe rocks. The rocks may appear to readers as insignificant but they are fossil records that can be used to determine the age of earth. The author also uses pictures and graphs throughout the reading keeps my attention going.
2. How could you adapt this hook in your own case study? Visuals will be effective in getting the readers attention, so using images to go along with the reading I think will be a good hook.
3. Why was Lord Kelvin’s estimate of the age of the Earth wrong? It was discovered that radioactivity (energy from unstable atoms) is what warms the earth, and this process can determine the ages of fossils and rocks.
4. Use figure 3.3 to explain the most common way fossils form. When an organism dies, its body gets covered by layers of sediment overtime. As the sediments accumulate, the bones fossilize. Many centuries later the fossils can be exposed from erosion, or discovered in other ways such as digging.
5. How does coal form? Plant remains metamorphose into hard rocks (coal) when are they are exposed to intense heat and pressure then compacted.
6. What are 12C and 13C? Why does the ration of 12C to 13C differ between plants and air? How do we use this difference to infer details about fossils ecosystem? Carbon-12 is a stable isotope of carbon and is plentiful, and-carbon 13 is a stable isotope of carbon. Carbon-13 is more difficult for plants to take in as opposed to carbon-12 which is lighter. So the levels of carbon-12 in plants is higher, and the levels of carbon-13 in the air is higher. When organisms die, they can preserve the levels of carbon, which can be detected in their fossils. The measurements can provide evidence of what organisms ate and the environment they lived in.
7. Find some images of Ediacaran fossils and post them in your blogs. Be sure to indicate where you found the images!

http://universe-review.ca/I10-77-Ediacara.jpg
http://www.fas.org/irp/imint/docs/rst/Sect20/vendintro.jpg

8. Why do plants colonize land before animals? According to the article, it appears that fungi and worked together to get on land. This made their expansion faster, compared to the colonization of animals.

9. How does this reading tie to the learning goals for this course? I think this article provides a great overview of the theory of fossils and the origin of life, which pertains to the course. This step-by-step reading can serve as a guideline of where science is today with fossilization and the evolution of earth.

Discussion Questions Mar 31

Discussion questions
Mar 31
Gonick 2001

1. What hook does the author use to capture your attention?

The author uses a creative comic style with lots of images and sketches along with short texts that provide a precise information towards the history of the universe.

2. How could you adapt this hook in your own case study?

Images have a great impact on how readers come to understand the material, so I think this form of visuals is effective in keeping the reader drawn to the text while comprehending the material. Animation in particular is somewhat childlike which can make the information more fun to read and follow.

3. Why was the Earth more radioactive four billion years ago?

According to the process of calculating the age of rocks, rocks contain radioactive elements; and when they decay they form into solids (never really disappearing). Also, it appears that the beginning of earth was a pool of chemicals that generated heat. Therefore the calculation of dating rocks suggests that the oldest rocks are as old as the earth.

4. What is remarkable about the fact that the oldest evidence for life is found in the oldest sedimentary rocks—that is, the oldest rocks that can possible contain fossils? (think about it; you may need to look up what sedimentary rocks are)

If the oldest sedimentary rocks (the very top layer of the crust) contained fossils, that can provide not only the time period of when the material existed but evidence of some form of life (animals, plants, etc) in that time.

5. The first mass extinction event in the History of Life was triggered by organisms who changed their environment so quickly, that they couldn’t survive in new environment that they created. Explain the circumstances of this extinction event. Over what time scale did it occur?

The story describes that as algae evolved chloryphyl emerged which created a news ource of energy. As the algae continued to eat it released oxygen which formed the ozone layer. As a result species polluted eachother. It appears to have occured 3 billion years ago.

6. What are some of the advantages of sex (from an evolutionary point of view)?

While asexual organisms reproduced exact copies of themselves, sex beings benefited from adopting various genes from the parents which helped them to survive to the ongoing changes in their environment. Sex was also advantageous in making evolution occur faster. Sex-producing species did not live infinitely.

7. What is a notochord?

A notochord became a protective layer for the central nervous system of a invertebrate; a spine or vertebrae, in other words.

8. One of the keys to evolution is that natural selection modifies features in an ancestor, adapting them to new functions. Explain this point using the evolution of the mammalian ear (see p. 23 of the reading).

From a natural selection point of view, the evolution of the mammalian ear may be understood as a result of adaptation, acclimation, or genetic mutation of a mammal as a means of survival. Competition in hunting, for example, may have triggered this development.

9. Describe three events that occurred in the history of life after the Devonian.

1. Jurassic era: this earlier period of dinosaurs demonstrates how these reptiles came to diverse and evolve. Fairly large species grew even larger, and some smaller species developed as birds. Continents began to separate, however, causing habitats to change and species to drift from each other.

2. Cretaceous period: this is a time of great diversity; the food chain escalated varying from plants to birds to Tyrannosaurus Rex. Something caused a drastic change in this ecosystem, however, in which species on the higher level of the food chain (particularly the larger animals) suffered from a lack of food and other sources. Perhaps their large presence in comparison to the smaller mammals required more energy and effort to survive.

3. Age of Mammals: by this time, continents were positioned much like how we know them today. The remaining mammals that survived from the Cretaceous era populated the land, and from this stemmed a growing diversity of birds, terrestrials, and marine animals. Mammals also began to grow larger and eventually hunted each other. This process created adaptations among different species: some developed defense techniques such as horns and armor; others excelled in speed and outrunning predators. The Miocene era suggests the beginning of the apes which heavily populated the trees. This period leads us into how we come to understand the age of humans.