Jama Messner
BY 124L- B6
September 18, 2018
“I’m Looking Over a White-Striped Clover: A Case of Natural Selection”
Exercise 1:
Using the information in Table 1, briefly summarize the habitat features for white clover in each state.
The habitat for white clover in Minnesota is at a higher elevation, rising to an average of 0.365km, compared to North Carolina’s average elevation of 0.213km. Because Minnesota is farther Northwest, its temperatures are much colder for a longer period. It’s mean number of days below 0°C is 154, compared to North Carolina’s average of 75 days below freezing. Conversely, North Carolina has 38 days with high temperatures reaching above 32°C, almost 2.5 times more than Minnesota, which only reaches 32°C 14 days per year. The average monthly temperature range for Minnesota ranges 48°, with a low of -19.4°C-28.6°C. With a slightly smaller range of 34°, North Carolina’s mean monthly temperatures range from -2.6°C-31.3°C. To correlate with warmer temperatures, the average yearly precipitation in North Carolina is almost double that of Minnesota, ranging from 107-117cm, compared to Minnesota’s average of 66-76cm of precipitation. Furthermore, because of warmer temperatures and precipitation, the herbivore (molluscs) presence in North Carolina is much more prevalent and active year-round, whereas in Minnesota, herbivores are not present in winter.
Exercise 2:
a. Why do you think the two gene products are stored in different parts of the cell?
The two gene products are stored in different parts of the cell so that it will take an additional step to activate the cyanide. Only under certain conditions cyanide will be produced.
b. Suggest at least two ways these products might come together to make active CN in nature.
Active cyanide could be made if an herbivore eats the leaf, causing the cell membrane to burst, combining its contents with the contents in the cytoplasm, resulting in active cyanide. Also, if a plant freezes and then thaws, this would cause the cell membrane to rupture, combining with the cytoplasm to produce active cyanide.
c. Suggest a reason that clover may produce cyanide. That is, what advantage does a plant gain by producing cyanide? Also suggest a possible disadvantage of producing cyanide. Or might there be no advantage?
Clovers may produce cyanide as a protection measure from herbivores and serve as a deterrent from being consumed as often. A potential disadvantage could be that if herbivores do not eat them, their reproduction might be lower (because their seeds are spread through animal feces).
d. It takes energy for an organism to produce a particular structure such as a stripe on a clover leaf that is otherwise plain. Why might cyanide-producing clover produce striped leaves? Cyanide-producing clovers might produce striped leaves as a deterrent to herbivores not to eat them because they are poisonous. If they did not have the white stripes, they would get eaten more because animals would not know...
