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Describe three attributes of habitat patches that could affect population density and rates of immigration and emigration.

WHAT IF? Suppose you were studying a species that has a population cycle of about ten years. How long would you need to study the species to determine if its population size were declining? Explain

MAKE CONNECTIONS Negative feedback is a process that regulates biological systems (see Concept 40.2). Explain how the density-dependent birth rate of dune fescue grass exemplifies negative feedback.

How does a human population鈥檚 age structure affect its growth rate?

How have the rate and number of people added to the human population each year changed in recent decades?

Type 鈥減ersonal ecological footprint calculator鈥� into a search engine and use one of the resulting calculators to estimate your footprint. Is your current lifestyle sustainable? If not, what choices can you make to influence your own ecological footprint?

Make a bar graph of the data in part 1. (For additional information about graphs, see the Scientific Skills Review in Appendix F and in the Study Area in Mastering Biology.)

What do the data represented in the graph suggest about the effects of cane toads on the predatory behavior of red-bellied black snakes in areas where the toads are and are not currently found?

Suppose a novel enzyme that deactivates the cane toad toxin evolved in a snake population exposed to cane toads. If the researchers repeated part 1 of this study, predict how the results would change.

Identify the dependent and independent variables in part 2 and make a scatter plot. What conclusion would you draw about whether exposure to cane toads is having a selective effect on the snakes? Explain.