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Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world’s largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins’ ability to respond to stressors? Has it affected the penguins’ secretion of corticosterone?
If penguins in a colony are habituated to the presence of tourists, how would their corticosterone response to being visited by tourists compare to that of penguins in a colony not previously exposed to tourists?

The results of Tyrone Hayes's experiments (Module 26.3) were published in a top peer-reviewed journal, yet the validity of his experiments has since been challenged. Using external sources, find out who has challenged the results.

Scientists set out to test the hypothesis that the herbicide atrazine is an endocrine disruptor that feminizes male amphibians. They treated male amphibians with atrazine and then compared their circulating testosterone concentration with those of males and females that were not treated with atrazine (controls). The results are shown here (* signifies P<0.05). Was the hypothesis supported? Why or why not?

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Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world’s largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins’ ability to respond to stressors? Has it affected the penguins’ secretion of corticosterone?

Corticosterone is a(n):

a. Neurohormone

b. Steroid hormone

c. Amino-acid-derived hormone

d. Polypeptide hormone

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Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world’s largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins’ ability to respond to stressors? Has it affected the penguins’ secretion of corticosterone?

In what part(s) of a target cell would you expect to find corticosterone receptors?

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Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world’s largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins’ ability to respond to stressors? Has it affected the penguins’ secretion of corticosterone?

Scientists tested the hypothesis that penguins habituated to tourists have a blunted stress response overall. They examined the corticosterone response of habituated and non-habituated penguins to another stressor—that of being captured and restrained for 30 minutes. They found that both habituated and non-habituated penguins secreted corticosterone in response to being captured and restrained, but that the level of corticosterone after 30 minutes differed between the groups. The results are shown here (* means P<0.05). Was the hypothesis supported? Explain.

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Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world’s largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins’ ability to respond to stressors? Has it affected the penguins’ secretion of corticosterone?

In response to a visit by tourists, which penguins—habituated or non-habituated—would show a greater change in expression of genes for liver enzymes involved in converting amino acids to glucose? Explain.

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Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world’s largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins’ ability to respond to stressors? Has it affected the penguins’ secretion of corticosterone?

Suggest at least two distinct physiological mechanisms that could be responsible for the difference in corticosterone response to a stressor in habituated and non-habituated penguins.

DRAW IT In mammals, the production of the hormone IGF-1 by the liver is controlled by growth hormone (GH) and GH-releasing hormone. Draw a simple sketch of this pathway, including glands, tissues, hormones, routes for hormone movement, and effects.