The gene pool of a species includes all the genes in the population.
Click on image for full size
Windows to the Universe original image

Changes to the Gene Pool: Microevolution

See all the frogs in the picture at the left? Let's pretend that they are all the same species and live in the same area so they are one population. Even though all the frogs are the same species, they do not all look the exactly the same. What's different about some of the frogs? Color!

All of the versions of the genes in a population of a species are together called the gene pool. All of the genes for color that are found in the population are part of the gene pool. Colors that are very common, like green, are very common in the gene pool. The genes for less common colors are less common in the gene pool.

The gene pool does not always stay the same. Over generations, small changes in the amount of each type of gene can happen for a number of reasons.

  • Genes can mutate if something odd happens when cells divide. This can create a new type of gene. Perhaps this is now the gene for purple frogs was developed. The new purple gene is a small part of the gene pool.
  • If a bunch of red frogs move into the area, it would add more red genes into the gene pool. This would make more red frogs in the next generation.
  • If the red and purple frogs decided to more elsewhere, they would form a new gene pool that didn't have any green in it. And, the gene pool they came from would have only green in it.
  • If these frogs live in an area with red rocks, the red frogs would be camouflaged and easily able to avoid predators. Red frogs would be more likely to survive and reproduce, making more red frogs. This would increase the amount of red genes in the gene pool.

Changes in the gene pool of a population over time that result in changes to the varieties of individuals in a population are called microevolution. Examples of microevolution include bacteria that have become unaffected by antibiotics, or a change in a species' coloring or size. If the changes are over a very long time and are large enough that the population is no longer able to breed with other populations, it is considered a different species. This is called macroevolution.

Last modified October 15, 2011 by Jennifer Bergman.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Chromosomes, DNA and Genes: Tiny Things That Have a Huge Effect on Who We Are!

Do you look a bit like your brothers or sisters? Do you look a bit like your parents? You may look alike because, unless you were adopted, you and the other members of your family have genes in common....more

Fish Adapting to a Changing World

Scientists have been studying stickleback fish to learn more about how animals cope with changes in their environment. Some stickleback fish live in the ocean while others live in freshwater. That’s a...more

Can there be Life in the Environment of Jupiter?

Jupiter's atmospheric environment is one of powerful winds, going 250 miles per hour, and temperatures from -270 degrees to +32 degrees (freezing temperature). These winds make it hard for life forms to...more

The possible discovery of Life on Mars

In July, 1996 a team of scientists said that they had discovered possible fossils of bacteria in a meteorite named ALH84001 that came from Mars. It was found in Antarctica in 1984 after having landed there...more

The Environment of Saturn

Saturn's atmospheric environment is one of powerful winds, going 250 miles per hour, and temperatures from -270 degrees to +80 degrees. With winds like these, it is hard to have peace and quiet. The region...more

Can there be Life in the Environment of Titan?

The air of Titan is a lot like the Earth's, except that it is very cold, from -330 degrees to -290 degrees! Like the Earth, there is a lot of Nitrogen and other complex molecules. There also may be an...more

Autotrophs

Organisms that are able to "make their own food" are called autotrophs, meaning "self-feeders". Some examples of autotrophs are plants and algae (shown in the picture). Both plants and algae use photosynthesis...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA