tedarling's blog

The evidence supporting the hypothesis that EPAS1 is responsible for the Tibetans adaptations to altitude is abundant. In one study researchers compared the genome of indigenous highlanders to closely related Han Chinese individuals. The EPAS1 gene displayed the most variation between the two populations. The variation in gene frequencies can likely be explained by natural selection, as a version of the EPAS1 gene was more advantageous to tibetan highlanders and resulted in increased fitness. Another group of researchers sequenced 50 exomes of Tibetans to identify genes showing population specific allele frequency changes. The EPAS1 gene again displayed the strongest signs of natural selection. “One single-nucleotide polymorphism at EPAS1 shows a 78% frequency difference… representing the fastest allele frequency change observed at any human gene to date (Xin Yi et al., 2010).” The adaptations that allow Tibetans to live at high altitudes are conclusive evidence that modern humans are evolving. The traits may have arose through mutation, but since they offered a selective advantage they increased in frequency - a process known as evolution by natural selection.

One example of recent modern evolution lies in the Tibetan highlands. At high altitudes oxygen availability is reduced which contributes to altitude sickness, marked by fatigue, insomnia, and nausea. People who are not acclimated or well adapted to life at high altitude suffer serious health issues. “Individuals from low-altitude populations who move to live at high altitude suffer from a number of potentially lethal diseases specifically related to the low levels of oxygen and struggle to reproduce at these altitudes. The hypoxia of altitude would thus have exerted substantial evolutionary selective pressure (Cynthia Beall et al., 2010).”  However, Tibetan highlanders can comfortably reside at elevations above 4,000m or 13,200 ft. The adaptations in tibetan populations that allow them to live at high altitude originates from the EPAS1 gene. This gene encodes for a transcription factor used in the induction of genes regulated by oxygen. The protein is induced when oxygen levels fall and controls the production of red blood cells. Tibetans actually produce fewer red blood cells than their lowland counterparts. An increase in blood cells is only beneficial to a certain point in delivering oxygen to tissues. Having too many red blood cells will make the blood too viscous to efficiently oxygenate tissues. Therefore, the changes in the EPAS1 gene ultimately make Tibetans less likely to overproduce red blood cells at high altitudes. The version of the EPAS1 gene found in tibetans varies from the versions of the gene found in any extant human population, it is unique and seems to be adapted to this specific environment.

The portrait picture of the entire plant was placed on the left side. The landscape picture of the flower was placed in the upper right corner. The landscape map of the range of Camellia japonica was placed in the lower right corner. Each of these three elements were labeled A, B, and C respectively by placing the letter directly above the image, in the top left corner with 6pt font. No other markings or labels were added. The two landscape images were near 600 pixels by 330 pixels. The portrait image was near 330 pixels by 600 pixels. The individual elements were padded with approximately 90 pixels worth of white space. The white space was between all elements and also between the elements and the border.

The portrait picture of the entire plant was placed on the left side. The landscape picture of the flower was placed in the upper right corner. The landscape map of the range of Camellia japonica was placed in the lower right corner. Each of these three elements were labeled A, B, and C respectively by placing the letter directly above the image, in the top left corner with 6pt font. No other markings or labels were added. The two landscape images were near 600 pixels by 330 pixels. The portrait image was near 330 pixels by 600 pixels. The individual elements were padded with approximately 90 pixels worth of white space. The white space was between all elements and also between the elements and the border.

A map of the range of Camellia japonica was made using https://mapchart.net. It is natively found in China, Taiwan, South Korea and Japan, so these countries were selected with the default red color. Even though the distribution of the plant is only Asia, a world map was used to highlight that it is not found in other continents. The figure was constructed using photoshop.

One photograph was taken in portrait orientation to show the full plant, including the pot. The plant was centered in the photograph both vertically and horizontally and the the picture was taken from an angle slightly looking down on it. Another photograph was taken in landscape orientation, focusing only on the single, vibrant pink flower. The flower was also centered in the photograph both vertically and horizontally and the picture was taken from an angle slightly looking down on it.

The plant photographed was Camellia japonica. It was located in the Durfee Conservatory and Garden at UMass Amherst. The room in which it was found is called the bonsai/camellia house, and was accessed through the westernmost entrance facing the Morrill buildings. Camellia japonica is located on the rightmost side, second to last in the row. The plant itself is approximately half a meter tall, with a single pink flower and moss covered soil.

Differences

• Figures A, B, and C not vertically aligned
• Small black speck on plate
• Plate polish
• Different fruits
• Shadows
• Text size
• Title alignment

Figure A

• Angle (bird's eye)
• Background
• Skin thickness

Figure B

• Angle (bird's eye)
• Background
• Color (pale green)
• Shape

Figure C

• Angle (bird's eye)
• Background
• Color (white/tan)
• Stem

Possible Reasons

• Did not specify background
• Did not specify angle
• Can not use exact same plate and fruits

Observation: Class attendance seems low today.

Inference: It's the friday of a long weekend, and some people skipped.

With the advent of technological innovations, humans are now capable of modifying the environment at a previously unprecedented level. Advances in medicine, such as the development of penicillin, have saved countless lives. Modern agricultural methods have vastly improved the amount of food that can be harvested. Building towns and infrastructure has ensured that people are no longer isolated from each other. At first glance it may seem as though these recent changes in human history would halt evolutionary change. However, modern humans certainly still face challenges to survival and exhibit varying reproductive success - the fodder for evolution.