The mountain gorilla, spotted owl, giant panda, snow leopard, and grizzly bear are all endangered by human encroachment on their environments. Another thing these animals have in common is their K-selected life history traits. Why might they be more easily endangered than animals with r-selected life history traits? What general type of survivorship curve would you expect these species to exhibit? Explain your answer.

What is survivorship?

What does a survivorship curve show?

Explain what the three survivorship curves tell us about humans, squirrels, and clams.

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

Burmese pythons were first found in the wetlands of Everglades National Park in the 1980s, but only rarely. The accompanying graph shows what happened next. Most of the data are derived from chance encounters of pythons on roads (pythons are notoriously difficult to find). How would you describe the type of population growth in pythons from 2000 to 2008?

a. Logistic

b. Exponential

c. Linear

d. Logarithmic

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

Researchers hypothesize that the severe winter of 2010 caused the decline in the number of pythons encountered that year. Is cold weather typically a density-dependent factor or a density-independent factor? Explain the difference.

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

The data in the graph show the number of pythons that were encountered, not the total number of pythons in the population. Design a mark–recapture experiment to estimate the total population size of pythons, and list at least two assumptions you would be making in your experiment.

Another hypothesis for snowshoe hare population cycles proposes that they are caused by sunspot activity. According to this hypothesis, sunspot activity affects the chemicals present in the plants eaten by hares, which in turn affects the quality of the food.

What testable predictions are generated by this hypothesis?

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Burmese pythons (Python molurus bivittatus) are constricting snakes that can reach enormous sizes (up to 7 meters in length). They are native to Southeast Asia but were released into southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem?

A life table would help researchers make predictions about python population growth. If you were to track a cohort of pythons over time to construct a detailed life table, what kind of data would you want to collect?

Many people regard the rapid population growth of developing countries as our most serious environmental problem. Others think that the growth of developed countries, though slower, is actually a greater threat to the environment. What kinds of environmental problems result from population growth in

(a) developing countries and

(b) developed countries?

Which do you think is the greater threat? Why?