A mountain stream warms by 3 degrees Celsius over thirty years. Trout in it vary widely in heat tolerance, and a few individuals already feed normally at the new temperature. What is the most likely outcome for this population over fifty generations?

The graph plots how many species of one crocodile group appear in the rock record in each interval. Which model of the rate of change does the graph support for this group?

Four lizard species on one island carry similar amounts of genetic variation. A fungal disease arrives and kills about 90 percent of each species on the island. Which species is at the greatest risk of extinction?

Use the timeline of the five largest mass extinctions. Which gap between two consecutive events on it is the longest?

A forest beetle can digest the leaves of only one tree species. A fungal disease kills 95 percent of those trees within ten years. What is the most likely outcome for the beetle population?

A snail occurs in every bed of a cliff face over 6 million years with no measurable change in shell coiling. In the next bed up it is gone and a clearly different coiling appears, with no forms in between. Which pattern does this record show?

A national park loses half of its old-growth forest to logging. Which resident animal is made most vulnerable to extinction by that loss?

The graph plots how many species of one mammal family are found in each interval of the rock record. Which statement best describes how this family disappeared?

A new volcanic island cools and one seed-eating bird species colonizes it. The island holds many empty habitats with seeds of very different sizes and hardness, and no competing birds. What is the most likely long-term outcome?

The graph plots the percentage of marine genera lost in each interval of the fossil record. What does the reading for the last interval indicate?

A river is dammed and its flow changes within a single year. Which fish species is least able to keep pace with that change through natural selection?

A quarry exposes twelve beds of shale. A clam's mean shell length is 11 mm in the lowest bed and rises by about 1 mm in each bed above it, reaching 22 mm at the top, with every intermediate length present. Which model does this sequence fit?

Acid runoff lowers a lake's pH from 6.8 to 5.2 over fifteen years, and shell material dissolves faster at the lower pH. The lake's snails vary hardly at all in shell thickness. Predict what happens to the snail population.

The graph plots how many families of one mammal group appear in each interval of the rock record. Which description fits the change the graph shows?

A volcano is expected to erupt and bury one valley. Which of these plants is most likely to be driven extinct by the eruption?

Use the graph. About what share of marine genera was lost between 444 and 443 million years ago?

Winters in a temperate region grow milder over forty years. A tick species that dies below minus 15 degrees Celsius has until now been confined to the southern edge of the region. What is the most likely outcome for the ticks?

Use the graph of marine genera through one boundary. Was the loss gradual or abrupt?

Two bird species on an island each number about 300. One descends from many founders and carries a wide range of immune gene variants; the other descends from two pairs released a century ago. Why is the second more likely to be lost to a new parasite?

Use the timeline of marine genera after one mass extinction. What does it show about the recovery?