Ecosystem Dynamics

Once students understand how plants are affected by pollution, they focus on how an ecosystem is affected by pollution, they focus on how an ecosystem is affected by a change in the environment. They analyze the interconnected nature of an environment and the organisms that live there by investigating how predation is affected when the plants in an environment change.

• All organisms have traits—physical or behavioral characteristics. Organisms inherit traits from their parents when their parents reproduce as part of their life cycle. 
• Over many generations, a population of organisms can develop adaptations that help them survive in their environment. 
• All animals, including humans, have senses. Senses are how animals get information about the outside world. Senses include sight, hearing, touch, taste, and smell. 
• A behavior is an organism’s response to a stimulus (anything in the environment that causes an organism to react).
• Organisms depend on their environment, and when the environment changes, it affects which organisms are able to survive there.
• When the environment changes, it affects which organisms are able to survive there.
• Humans can change the environment in ways that affect the survival of different organisms.
  
  

• Why do variations in traits help some organisms survive and reproduce?
• How do variations in traits lead to adaptations over time?
• How has the cottontail rabbit adapted senses to its environment?
• How does the information gathered by an animal’s senses contribute to the overall functioning of the animal system?
• Why do organisms depend on their environment for survival?
• What do all plants, regardless of their particular environment, require for life?
• Why are rabbits often found in areas where there are a lot of different kinds of bushes and shrubs growing between forests and open grasslands?
• Why do predators eat rabbits?
• How will rabbits likely be affected when humans clear the land of the majority of shrubs and bushes?
• Why does clearing the land make ecosystems less stable?
• What would happen if none of the rabbits had a trait that helped them survive the changed environment?
  
  

Misconception: Adaptations are developed by individual organisms in response to the needs of the individual.

Fact: Adaptations are developed over generations in response to environmental pressures.

Misconception: The environment is static and unchanging.

Fact: Environments change all the time, from both natural and human causes.

Adaptation : a trait that helps an organism survive in its environment

Behavior : an organism’s response to a stimulus

Change :  to make something different from what it is now

Heredity :  the passing on of traits from parents to children

Inherit :  to receive a trait from your parents or ancestors

Life Cycle :  the series of developmental stages an organism passes through on its way from birth to death

Pollution :  any substance that has harmful effects on the environment

Predator :  an organism that eats another organism

Reproduction :  the ability of a mature organism to have offspring

Sense :   how animals get information about the outside world

Stability :   a condition in which the parts of a system are unchanging

Trait :   a physical or behavioral characteristic of an organism

Cottontail Rabbits

Small trees, shrubs, vines, and tall grasses are the favorite hiding places of cottontail rabbits. Cottontail rabbits spend much of their time hiding because they have many predators. A predator is an organism that eats another organism. Raccoons, foxes, hawks, owls, snakes, cats, and dogs all prey on them.

The cottontail rabbit can run at speeds reaching 29 kilometers (18 miles) per hour. When running from a predator, it runs in a zigzag pattern to confuse the predator.

Cottontail rabbits get their name for their poofy tails. Their tail is an example of a trait. A trait is a physical or behavioral characteristic of an organism. Size and color are other examples of physical traits. Running in a zigzag pattern is an example of a behavioral trait. A behavior is an organism’s response to a stimulus (anything in the environment that causes an organism to react).

Traits and Heredity

When rabbits reproduce, they pass along traits to their offspring. This passing on of traits from parents to children is called heredity. Heredity causes offspring to have traits that are similar to their parents and to their siblings.

There are patterns that occur as traits get passed along. Heredity explains why offspring look similar to their parents. This is because they inherit traits from their parents. To inherit means to receive a trait from parents or ancestors.

Heredity explains why baby cottontail rabbits have similar poofy tails, long ears, and running abilities as their parents.

However, offspring don’t look or act exactly like their parents. There are always some differences. These differences are called variations. For example, some cottontail rabbits are bigger than others. Some rabbits can run faster than the other rabbits.

Rabbit Adaptations

Sometimes, variations in traits can provide advantages in surviving, finding mates, and reproducing. For example, a rabbit that blends into the environment more than the other rabbits might be better able to avoid predators. Similarly, a rabbit that can run faster than the other rabbits can outrun predators.

Over time, these variations can become more common in the rabbit population because rabbits without the advantageous traits die out. They become adaptations— traits that help an organism survive in its environment. To change is to make something different from what it is now.

Adaptations are developed across generations in response to the environment. For example, cottontail rabbits have adapted strong senses to help them survive. A sense is how animals get information about the outside world. Senses include sight, hearing, touch, taste, and smell. For example, the rabbit has large eyes that stick out on either side of its head. This allows it to spot predators from all directions. It also has large ears that allow it to hear predators that may be approaching.

In this lesson, students figure out how predation is affected when the physical characteristics of one organism in the environment change. Students use a model to observe how a population of one organism is affected when the habitat changes, specifically their hiding places. Students investigate the phenomena of population collapse and its effects on other populations in the organisms’ food chain and food web. Students use the data they gather from their experiments to construct an explanation about how an organism has adaptations that help it survive in its environment, and how a change to the environment can affect the organism’s ability to survive.