Rock Pocket Mouse

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Explore how short- and long-term environmental changes
affect organisms and traits in subsequent populations; and

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Warm up

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice Forest Biome Food Chain

A food chain shows a direct flow of energy in an
ecosystem. Energy from the sun is converted into
chemical energy (sugar). The chain then shows how
the energy is passed to each organism.

Autotrophs make their own food
Primary consumers are plant eaters (herbivores)
These herbivores get eaten by secondary consumers
Secondary consumers up to top predators are called “carnivores”

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice Forest Biome Food Chain

Natural Selection: Rock Pocket Mice Texas standard 8.11 C

Energy Pyramid

Energy pyramids show the numbers of each population in an
ecosystem. The number of organisms will decrease as you go up
the pyramid.

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Introduction

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Rock pocket mice are a very small variety of mouse that live in the desert
regions of the U.S. They are called pocket mice because of their size, only
weighing as much as a handful of paperclips.

Pocket mice spend a lot of their time in the cool underground in an attempt
to avoid the hot desert sun. They must eventually venture outside the
burrows in search of water and seeds. Once outside, pocket mice are on
the lookout for desert predators. Snakes, coyotes, owls, foxes, and hawks
all have mouse on the menu.

The pocket mouse has a natural fur color that blends in well with the sandy
rocks and terrain of the desert ecosystem. In recent years, scientist have
observed and studied a mutation in the fur color of rock pocket mice. Dark
rocks resulting from lavas flows has become an advantage to mice with the
mutation.

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Guided Practice

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Several years ago scientists noticed a mutation was occurring in the mice fur color.
The natural fur color of the mice is sandy brown and matches the desert
landscape. Every now and then a glitch in the mouse DNA produces an offspring
with dark color fur. The change is random and cannot be predicted or controlled.

Mice have from 2-7
offspring at a time

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Charles Darwin is credited with the idea of
natural selection. His observations and
writings led him to the conclusion that events
in nature will cause organisms with certain
characteristics to have an advantage over
those without that trait.
This is what scientist observed with the rock pocket mice.

Most desert predators rely on keen eyesight to locate pocket mice. The tan-
brown fur color of the mice helps them blend in with their surroundings and
avoid detection.

Brown fur is a natural Dark fur mutation is a
advantage. More brown disadvantage. Dark fur
mice are easily spotted
fur mice survive.
by predators

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

The Game Done Changed…

When flowing lava cools it turns a dark-charcoal color.
Increased lava flows over the years have changed the
landscape. This natural event now favors the mice with dark
color fur and is a good example of natural selection.

Dark fur mice in this ecosystem
have gained an advantage as the

result of a natural event.

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Independent Practice

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

The Making of the Fittest: Natural Selection and Adaptation

This video documentary details the evolution of the rock pocket mice
in the southwest desert region of the United States. Pay particular
attention to the explanations of mutation, adaptation, evolve, and
natural selection.

Texas standard 8.11 C

Natural Selection: Rock Pocket Mice

Assessment