Prairie dogs once covered the expanses of the Great Plains. Their grazing made the grass more nutritious for the huge herds of bison, and a variety of snakes, raptors, and mammals   preyed on the rodents. In fact, the black- footed ferret (now endangered) specialized in prairie dog predation. Today, growing housing and agricultural developments have covered many prairie dog towns. Which of the following statements about prairie dogs is true?

#Question id: 4643

#Section 2: Evolution

The treeʹs horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Letʹs say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.

How many separate species, both extant and extinct, are depicted in this tree?

#Question id: 12107

#Section 1: Ecology

#Question id: 11356

#Section 1: Ecology

The Lotka-Volterra population models for predator and prey result in:

#Question id: 12316

#Section 1: Ecology

#Question id: 3425

#Section 2: Evolution

Many evolutionary forces are operating in population. In study, within population increase genetic variation due to -----A-----while decrease genetic variation due to ------B-----. Between populations increase genetic variation due to -----C-----while decrease genetic variation due to ------D-----.