Assessment Questions 7.19

1. Since 1500 C.E., how many terrestrial vertebrate species are estimated to have become extinct according to the passage?

322 terrestrial vertebrate species.

2. What decline in the size of wild animal populations has been observed worldwide over the past 40 years, on average?

An average decline of about 25% in the size of wild animal populations.

3. According to the International Union for the Conservation of Nature, what percentage of amphibian species is currently characterized as "threatened"?

Over 40% of amphibian species.