benjaminburk's blog

The purpose of our project was to study the windows and doors of Morill 4 south for signs of arthropod inhabitance. Arthropods are more commonly referred to as insects. The signs we were looking for included live bugs, dead bugs, exoskeletons, webs and/or any cracks or openings that could be used as access points for them. We took two recordings a few days apart hoping to see a change in the number of signs present. In the graphs in the middle of the poster you can see the relationship between the various signs (dead bugs, live bugs and spider webs) and the distance from the window sill or door to the reptile located on the 5th floor in Morill. In general based on the graphs you can see that the number of signs of arthropods increased as the location got closer to the reptile room. We believe the reason for this is because of the luxury effect, which describes ecosystems shaped completely by human interaction. In this scenario more sign of arthropods were found on the fourth floor because there is less foot traffic on the third and fourth floor as compared to first and second floor. 

Dan and I both believe that the parents should have the right to test their daughter. Although the hospital is correct in saying the daughter will have her own choice once she turns 18. The fact that she is seven means that under the current conditions the parents have control over medical decisions in her life. Not to mention that by testing her the parents can make more informed decisions on what is best for their daughter and family, such as moving out a polluted environment. Jala believes that because of the personal effects of the genome screening and the fact that typically the disease doesn’t arise until the age of 20 that the hospital is correct in denying the parents request. She believes that the daughter will be able to make an informed decision at the age of 18 without major risks because the disease typically doesn’t arise till age 20 and because it is only 80% penetrant.

The purpose of our project was to study the windows and doors of Morill 4 south for signs of arthropod inhabitance. Arthropods are more commonly referred to as insects. The signs we were looking for included live bugs, dead bugs, exoskeletons, webs or any cracks or openings that could be used as access points for them. We took two recording a few days apart hoping to see a change in the presence of arthropods. In the graphs in the middle of the poster you can see the relationship between the various signs (dead bugs, live bugs and spider webs) and the distance from the window sill or door to the reptile located on the 5th floor in Morill. In general based on the graphs you can see that the number of signs of arthropods increased as the location got closer to the reptile room. We believe the reason for this is because of the luxury effect, which describes ecosystems shaped completely by human interaction. In this scenario more sign of arthropods were found on the fourth floor because there is less foot traffic on the third and fourth floor as compared to first and second floor. 

The video “Great Human Odyssey” is an informative video that walks the viewer through important discoveries made throughout history that help construct the timeline of homo sapien evolution. The overall message of the video is that Homo sapiens as a species are extremely adaptive and are the only species in the world that has been able to cover the entire globe and conquer all types of climates and terrains. Also the video drives home the idea that this adaptive nature is what allowed Homo sapiens to avoid mass extinction, a fate that wiped their ancestors out and pushed them as a species to the brink. I enjoyed the examples of current groups that live like the ancestors, for example the Sans Bushmen who use the “persistent hunting” technique in order to hunt prey, this is the same technique scientists believe that the Sans’ ancestors used when hunting game. I did find that at some points the video was a little bit dry and very heavy with information. But overall I found the video interesting and enjoyable.

In the data gathered above Table 1 describes the amount of food vacuoles observed in 10 random Tetrahymena cells with the average of the timeslot and standard deviation of the observation. In Table 2 the same readings are represented, but the difference is that the observed Tetrahymena have been treated with 1ul of serotonin. Figure 1 is a graphical representation of the averages of  Tetrahymena food vacuoles observed within the control group at various times, with the standard deviation noted with error bars and Figure 2 is a graphical representation of the averages of Tetrahymena food vacuoles observed within the experimental groups at different times, with the standard deviation noted with error bars. In Figure 1 we see a positive slope meaning that more food vacuoles on average were seen in the Tetrahymena as time went on and we also see a small value of standard deviation meaning that the counts among the 10 randomly selected cells were similar values compared to the mean. The only exception for the pattern of small standard deviation is seen when time 15 where it jumps to 4.3 meaning that the amount of vacuoles observed varied greatly from the mean at that time. Meanwhile in Figure 2 from time 0-10 a positive slope is observed meaning that the number of food vacuoles observed is increasing and then at time 10-15 there is a negative slope meaning there was a drop in the number of food vacuoles observed from 13.7 to 10.9 vacuoles on average and lastly in time 15-20 there is a positive slope meaning that there was an increase in observed food vacuoles again from 10.9 to 13.8 vacuoles on average. In the experimental the standard deviations at each time are relatively small meaning that the number of food vacuoles observed were more or less similar to the average of the entire time group. Between the two tables and figures we see that on between 0 and 10 minutes on average there are more food vacuoles observed in the cells treated with Serotonin, but in minutes 10 to 15 there are more vacuoles observed on average in the control group. Also in all times except for 15 minutes the standard deviation of the counts were greater in the experimental group meaning that the counts gathered in the control group were more similar to the mean at 0, 5, 10 and 20 minutes.

Tetrahymena cells are unicellular predatory ciliates that produce both sexually and asexually. It is an excellent laboratory model because it possesses certain single cell advantages that are beneficial in the laboratory, while also sharing many genes with us multi-cellular animals (Cole 2000-2013). One interesting quality of the Tetrahymena is the way in which they feed. They feed in a process called phagocytosis, which results in the creation of small food vacuoles within the cell membrane (Coyne 2011). For the control group of this experiment the Tetrahymena cells were fed India ink and allowed to feed. Immediately after and then every five minutes for twenty minutes a random sample of Tetrahymena cells were taken and added to 50ul of glutaraldehyde, killing the cells without damaging the tissues. Once mixed, the Tetrahymena were put under a microscope and then ten randomly chosen cells had their black food vacuoles counted. The counts were averaged and the standard deviation calculated. Tetrahymena not randomly chosen were excluded from the experiment. For the experimental group the same exact procedure was followed, except for that initially along with introducing India Ink to the Tetrahymena we also placed 1ul of serotonin into the culture. We still took food vacuole counts of 10 randomly selected cells every five minutes for twenty minutes using the technique described in the control group procedure. In this experiment we decided to test the effects of serotonin on Tetrahymena food consumption. Based on previous experiments we are aware that serotonin stimulates the consumption of nutrients in Tetrahymena cells, therefore we hypothesized that the addition of the serotonin would lead to an increase in the number of food vacuoles observed compared to the amount observed in the control trials. With this being our hypothesis we hoped to find results that lead to higher vacuole count means for the group treated with serotonin, then the control group at all time points.

Fruit flies (Drosophila melanogaster) go through a 4-stage life cycle. A life cycle that is 11-14 days long providing an efficient option for observations in a laboratory setting (Potter 2000-2016).  This cycle can be altered simply by exposing the larvae to different hormones. We were eager to see the effect varying concentrations of Juvenile Hormone, a hormone essential to fruit fly development, inhibitor had on the life cycle of a fruit fly in a lab setting (Yamamoto R1, Bai H, Dolezal AG, Amdam G, Tatar M. 2013). Because of the fact that the juvenile hormone is essential to fruit fly development we hypothesize that the overall development will be stunted and predict to see a larger percentage of larvae in trials that contain a higher concentration of inhibitor and a lower percentage of pupae in trials that contain a higher concentration of inhibitor. We mixed 10ml of water (Control) or various concentrations (0.01, 0.1, and 1) Juvenile hormone (JH) Inhibitor with 2 grams of dehydrated fly media. We then added 2 male and 2 female flies to each tube. For a week we let the flies mate in the media. In the second week we removed all the adults from each trial and placed the tubes back into the incubator. After the third week we scored the vials for: number of larva, number of pupa, number of males and female adults, average length of adults. As you can see in Figure 1 there is an upwards trend seen in the percentage of larvae as the concentrations increase, as supported by the fact that 14% of flies in the 0.01 concentration were larvae and in the vial a concentration of 1 approximately 38.4% of the full population is larvae. Also in Figure 2 a downward trend is seen in the percentages of pupae, as supported by the fact that 63.4% of the population in 0.01 concentration were in the pupae stage, while the population with a concentration of 1 only had 35.1% of the population in the pupae stage.

Both factors, osmolarity and volume, of blood have lasting effects on the body and the functions that occur throughout. Both factors change independent from each other, but work together to maintain an overall homeostasis within the body. For example if an individual were to work out and drank only water then the overall osmolarity of the blood would decrease due to the increase of water. However the volume will not change because the water lost in sweat would be replaced by the water consumed. The change in the osmolarity would lead to a reduction of vasopressin release and an increase in renin production. The renin production increase would promote the reabsorption of sodium, bringing the osmolarity back to an equilibrium state. This is a prime example of independent pathways that work together within the body in order to maintain homeostasis. 

Throughout the process of this lab many mechanisms of evolution were observable, most prominently the mechanism of natural selection. In order for evolution by natural selection to occur three requirements must be met. The first is that individuals in the population must vary in trait that is being considered. Also the trait be considered must also be heritable, meaning it must be able to be passed down from generation to generation through germline cells. Lastly there must a selection differential, which simply means that the trait being considered must either increase or decrease the likelihood of the organism to survive and reproduce. This idea of evolution through natural selection was discussed throughout the SimUText Lab and was displayed during the Flat Periwinkle snail activity. In the activity the trait of Periwinkle shell thickness was shown to be variable, heritable and provided a selection differential, in the case of this trait a thicker shell resulted in a greater likelihood to survive and reproduce in an environment that contained predation by crabs. This trend of thicker shells leading to a higher likelihood of survival and reproduction in Flat Periwinkle populations was the driving force behind the constructed hypothesis for the effects of crab predation on the Dogwinkle snail population. The Dogwinkle snail species is the species under observation in the experiment, the Dogwinkle species exists in two distinct factions, an Eastern and a Western. In the Eastern population there is a predation pressure due to the presence of Rock Crabs and the average shell thickness of the Eastern population is thicker than the Western population in which there is no Rock Crabs present. With all of this information under consideration the hypothesis reads as follows, if there is predation by crabs present and the trait of shell thickness is being observed, then evolution by natural selection will occur and a shift to a larger average shell thickness in the experimental tanks containing the Dogwinkle snails can be expected.

As previously stated the original hypothesis constructed before the experiment was, if there is predation by crabs present and the trait of shell thickness is being observed, then evolution by natural selection will occur and a shift to a larger average shell thickness in the experimental tanks containing the Dogwinkle snails can be expected. Based on the results it is fair to conclude that this hypothesis is supported and that when predation by crabs is present evolution by natural selection occurs. This can be concluded because in all trials the average shell thickness of the tanks with crabs, the experimental population, increased significantly from day zero to day 160. For example in Figure 1 the average shell thickness of tanks with crabs increased from 7.175mm on day 0 to 8.875mm on day 160, a total increase of 1.7mm. Meanwhile there was no trend within the tank without crabs, the control population, and the change of average shell thickness within the population was either random or insignificant. For example in Figure 1 the average shell thickness of the tanks without crabs in them change from 7.175mm to 7.4mm, a total increase of .225mm, a much less significant change than the 1.7mm observed in the tanks with crabs. This change in the experimental population proves that evolution by natural selection occurred when predation by crabs was present because the fact that the trait of shell thickness was heritable and variable was already known, but the significant change from thinner to thicker shells in populations where predation was present proves that there is a selection differential when discussing shell thickness, more specifically it can be concluded that thicker shells provide the organism a higher probability to survive and reproduce. This conclusion reiterates the three requirements needed for evolution by natural selection to occur being, heritability, variability and selection differential. Also the interval and duration of the experiment being only 160 days shows exactly how quickly and effectively natural selection can occur in and change a population.