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Too Hot at the Edge: A Zoo's Pupfish Program

Grade 8 natural selection practice: use a zoo program's pupfish heat tests, survival counts and DNA data to explain who survives and reproduces.

Grade 8ScienceInteractive · Printable

Aligned toMS-LS4-4

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
12 questions
Classroom-ready

Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Matching, Circle the answer, Short answer

About this worksheet

What students practice

Students calculate survival percents to compare individuals with different inherited heat tolerance.
Students use survival, offspring and breeding evidence to explain how trait variation affects reproduction.

How to use

Read the passage together and make sure students know what each table counts; let them work the percent questions with a calculator before the matching and the written explanation.

Curriculum

NGSS standard covered

MS-LS4-4

Explain how genetic variation in traits makes some individuals more likely to survive and reproduce.

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Too Hot at the Edge: A Zoo's Pupfish Program

Use survival, offspring and breeding data to explain how variation in heat tolerance matters.

Part 1: Before and after the heat wave

Read the passage and Table 1, then answer the questions.

The Pupfish Pool

1The Redrock City Zoo runs a conservation program for a small desert pupfish that lives in only one spring-fed pool. The zoo keeps a backup population in its own tanks in case something happens to the wild pool. Eighth grader Marisol Tenorio spent her summer as a teen volunteer with the program's biologist, Dr. Anders Whitlock. The deep center of the pool stays near 30 °C all year. The fish can rest there, but they find most of their food and lay their eggs on the shallow edges, where the water heats up quickly on summer afternoons.

2In April, the team caught 150 adult fish, gave each one a tiny tag and measured its heat tolerance: the highest water temperature at which the fish could still swim normally. Each fish sat in a small tank while the water warmed slowly. As soon as a fish lost its balance, the team moved it back into 30 °C water, and the fish recovered within minutes. The results varied from 39 °C to 43 °C. The team sorted the fish into three groups of 50: low tolerance (39–40 °C), medium tolerance (41 °C) and high tolerance (42–43 °C). Then all 150 fish were released back into the pool.

3In July a heat wave hit. For nine afternoons in a row, the shallow edges of the pool reached 41.5 °C. In September the team set traps in every part of the small pool for a week and recorded each tagged fish they found alive. Table 1 shows the results.

4Most pupfish of this kind live only one or two years. The following spring, the team took a tiny fin clip from 100 young fish that had hatched in the pool in August and September, after the heat wave. A DNA test showed which tagged female was each young fish's mother. Table 2 in Part 2 shows the results.

5Back at the zoo, the team bred tank fish. They set up 10 pairs in which both parents had high heat tolerance and 10 pairs in which both parents had low heat tolerance. All of the young were raised in identical tanks at 30 °C with the same food. When the young became adults, the team measured them. Young of the high-tolerance pairs had an average heat tolerance of 42.4 °C, and young of the low-tolerance pairs averaged 39.7 °C.