If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Course: High school biology - NGSS > Unit 8

Lesson 2: Adaptation and environmental change
Science
High school biology - NGSS
Adaptation and environmental change
Adaptation and environmental change
© 2024 Khan AcademyTerms of usePrivacy PolicyCookie Notice

Apply: adaption and environmental change

Google Classroom

Problem

A population of snails lives in a forest habitat where they have several predators, including birds and small mammals. The snails have shells that can be either light, medium, or dark brown in color.
The number of individuals in the population with each shell color is shown in the following graph.
A bar graph shows three bars for snail shell color that extend upward from the x axis. The bars are labeled light, medium, and dark. The y axis represents the number of snails and ranges from zero to fifty. The bar for light shell color goes to eighteen snails. The bar for medium shell color goes to thirty seven snails. The bar for dark shell color goes to forty five snails.
The snails’ forest habitat has experienced several years of heavier-than-normal rainfall. As a result, the top layer of dark soil has eroded away and exposed a layer of lighter colored rock.
Given this environmental change, which of the following graphs represents the most likely distribution of shell color in the snail population after enough time has passed for natural selection to occur?
Choose 1 answer: