Although there are organisms whose life histories fall somewhere between iteroparity and semelparity, life history always represents a trade-off. Why is this?

Which of the following is most likely a density-dependent growth regulator of animal populations?

A particular environmental change causes the deaths of 25 individuals in a herd of 100 wild horses, and it kills 50 individuals in a herd of 200 horses. In this case, the growth of a wild horse population is most likely limited by __________. (Assume that the two herds are found in territories of equal size.)

A certain species of seal breeds and rears its young on rocky beaches. Competition for breeding sites is fierce, and males that do not secure a site will not reproduce. This behavior is an example of which mechanism of density-dependent population regulation?

Which of the following would most likely be an example of a density-independent factor limiting population growth?

A dog gives birth to three puppies one year. Three years later, she gives birth to six puppies. Which type of life history pattern is characteristic of this organism?

What are three basic issues that life histories entail?

When the per capita birth rate equals the per capita death rate, __________.

A population will always grow exponentially under what circumstances?