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The Park Goes Quiet: Silent Crickets on a Hawaiian Island

Grade 8 natural selection math: compute percents from five years of park cricket surveys and use a fly-larvae test and a model to explain why silent males spread.

Grade 8ScienceInteractive · Printable

Aligned toMS-LS4-6

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
9 questions
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Details

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

About this worksheet

What students practice

Students calculate the percent of flatwing males in each survey year and the change over time.
Students use a fly-larvae test and a simple model to explain why an inherited silent-wing trait spread.

How to use

Read the passage aloud, then let students use calculators for the percent questions; discuss the model in question 6 step by step before the written explanation.

Curriculum

NGSS standard covered

MS-LS4-6

Use math and data to explain how natural selection changes the share of a trait in a population over time.

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Name Date

The Park Goes Quiet: Silent Crickets on a Hawaiian Island

Use survey numbers and a simple model to explain how a trait became common.

Part 1: Five years of surveys

Read the passage and Table 1, then answer questions 1–3.

When the Singing Stopped

1Pacific field crickets live in the grassy lawns and fields of parks on several Hawaiian islands. On warm nights, a male cricket sings by rubbing his two front wings together. One wing has a ridge called a file, and the other has a hard edge called a scraper. The chirping song draws female crickets to the singer, and that is how most males find mates. Females lay their eggs in the soil, and the young grow into adults in a matter of weeks, so in the warm islands the crickets can go through several generations each year.

2The song also draws a small fly. A female of this fly hunts by sound: she follows a cricket's song to the singer and drops tiny larvae onto him. The larvae burrow into the cricket's body, feed inside him and usually kill him within about a week. Female crickets do not sing, so the fly rarely finds them. The fly came to Hawaii from North America, where it attacks other kinds of crickets.

3Some males have flatwings. They carry an inherited gene version that gives them smooth front wings with no working file or scraper, so they make no sound even when they move their wings. In a university lab where no flies were present, flatwing families kept producing flatwing sons generation after generation. A flatwing male cannot call females to himself. Instead, he waits in the grass near a singing male and meets some of the females that come to the song, so he usually mates less often than a singer does.

4Kekoa Albrecht-Ruiz, an eighth grader, helps biologist Dr. Hollis Ngata with a survey in one island park. Every June the team walks the same field at night, catches male crickets in nets, checks their wings under a flashlight and lets them go. In Year 1 the field rang with chirps on warm nights. By Year 5, Kekoa could cross the whole field and hear only a few singers, even though the nets still brought up plenty of males. The team's records are in Table 1. In Year 2, they also kept each male in a small cup for a few days to check for fly larvae (Table 2, in Part 2).