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Monarch Butterflies Take a Moment and Think of a Butterfly-Any Type of Type

question 347

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Monarch Butterflies
Take a moment and think of a butterfly-any type of butterfly at all. Chances are good that the distinct orange, black, and yellow monarch butterfly came to mind. The monarch is perhaps the most beautiful of all butterflies in existence. That is, to a human the coloration is beautiful, but not so for other animals. The coloring is like a flashing red light to potential predators, sending a warning that the insect is foul tasting and poisonous. However, the greatest threat to the wellbeing of the monarch butterfly might not be coming from predators, but from the activities of humans.
As larvae, monarch caterpillars feed almost exclusively on the milkweed plant. This plant is critical for their survival and adults will return to areas rich in milkweed to lay their eggs directly on the plants. The milkweed that they feed on contains a poisonous toxin that is then stored in their bodies. This is what makes the monarch butterfly taste so terrible to predators. An animal that eats a monarch probably won't die, but it will feel sick enough to avoid other monarchs in the future.
Perhaps the most amazing aspect of the monarch is its 3000-mile annual migration. Every year as winter approaches, millions of these insects leave their homes in the United States and Canada, heading south to Southern California and Mexico. They travel between fifty and one hundred miles a day, the entire journey taking up to two months to complete. The monarchs return to the same forests every year, with some landing on the same trees that their ancestors did years earlier. As many as one billion of these delicate creatures find their way to the mountains of Mexico each year. Towards the end of winter, the monarchs mate. The males die soon afterwards but the females fly north, depositing eggs on milkweed plants along the way. Eventually, they too will die along the journey. The eggs will hatch and the larvae will become butterflies. These insects then continue the journey north.
Sadly, this regal insect is facing a number of threats to its existence. For one, scientists predict that one major effect of climate change will be wetter and colder winters. If they are dry, monarchs can survive sub-freezing temperatures, but if they're wet, they will freeze to death. Furthermore, as summers warm, habitats that are suitable for them will begin to move further and further north. This results in longer migrations. Before long, the distances may simply be too much for the insects to handle. Finally, the monarch faces extreme habitat loss in Mexico. Illegal logging there has greatly reduced the forests where the butterflies head in the winter. This problem in particular has become so serious that the International Union for Conservation of Nature listed the monarch as a "threatened phenomena." Will the monarch survive? It seems that it is up to the actions of human beings.
Which of the following best rephrases the topic of the fourth paragraph of the passage?

Definitions:

Average Total Cost

The total cost of production divided by the number of goods produced, accounting for both fixed and variable costs.

Output

The total amount of goods or services produced by a firm, industry, or economy within a specific period.

Fixed Cost

A cost that does not change with the level of output or production, such as rent or salaries.

Short Run

A period in economics during which at least one input, such as plant size, is fixed and cannot be changed.