In this lesson, we will discuss what

In this lesson, we will discuss what happens when an organism is forced to deal with environmental changes. You will learn what adaptation is and how organisms benefit from it.

Environmental Change

It is the hottest day of the year and your air conditioner quits working. The temperature in your house goes from a cool 72 degrees to 85 in a matter of hours.

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Since you are used to living in an environment that is much cooler, this difference is a hard adjustment. You could compare this situation to the way animals are affected by environmental change.Any alteration of the normal state of an ecosystem is considered environmental change.

Environmental change can be the result of natural causes, like when lightning causes a forest fire. It can also result from human causes like the destruction of a rainforest to create farmland. When an ecosystem is changed, the organisms that live in the ecosystem can have an even harder time adjusting to the change than you do to the loss of your air conditioning. They respond to this challenge by a process called adaptation.


An adaptation is a genetic change, or mutation, that makes the organism better able to survive in its new environment. These mutations are a normal part of the variation that exists in any population.

Mutations can either be harmful, neutral, or beneficial. When one of these genetic changes is helpful, it will be passed down from one generation to the next until it becomes a typical characteristic of the organism. The mutation is now an adaptation.Adaptations can be either structural or behavioral. A structural adaptation is a change to some physical part of an organism. A good example of this is the way plants called succulents have adapted to life in a hot, dry climate. As the plant’s environment changed to that of a desert, the plants with mutations that allowed them to store extra water were better able to survive.

Over time, all of the plants developed this adaptation.A behavioral adaptation is a change to the way an organism behaves. Hibernation is one example of a behavioral adaptation. Animals that were unable to find enough food in the winter would often die.

Animals with a mutation that allowed them to sleep through the winter living off of stored food increased their survival rate and passed the adaptation on to their offspring.Remember, organisms do not change of their own accord. Instead, organisms in a population are born with a variety of traits. Environmental changes determine whether or not the adaptation of new traits will be beneficial to the survival of the species. This ability allows many organisms to survive the challenges of environmental change.

Evolutionary Rescue

Some organisms have the ability to respond to environmental changes by evolving rapidly. The environmental selection of useful traits can be so biased that the process of adaptation is noticeable within only one generation.

The shorter the life span of the organism, the quicker the change is passed to the entire population. Rapid adaptation such as this is called evolutionary rescue.The adaptation of plankton to a recent increase in harmful algal blooms is a good example of evolutionary rescue. Plankton were not typically able to eat the harmful algae blooms. However, some of the plankton had a genetic variation that allowed them to tolerate the algae.

The life span of plankton is only a few days. This allowed for rapid adaptation and within a few years the entire population of plankton was able to eat the algae blooms.

Lesson Summary

Environmental change is an alteration of the normal state of an ecosystem. It can be a result of natural causes or human causes and can create a challenging situation for the organisms that live in the ecosystem. Organisms often respond to environmental changes with adaptation, or a mutation that provides a better way for the organism to survive in the new environment. This genetic change is passed down to future generations until it becomes a typical characteristic of the organism.

The rapid occurrence of adaptations is called evolutionary rescue.Adaptations can be structural or behavioral. A structural adaptation is a change to a physical part of the organism. A behavioral adaptation is a change in the way the organism behaves.

It is not the organism, but the environmental changes that determine whether or not an adaptation will occur. The normal variation of traits in a population is what gives the organisms the ability to survive environmental changes.


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