Populations in a particular environment that have adapted to living conditions in that specific area are therefore better able to meet their survival needs and are more likely to survive and reproduce offspring with those key survival traits.
What is evolution?
The basic idea of evolution is that organisms change over time. Charles Darwin proposed that new species come from preexisting species by the process of natural selection.
Natural Selection
Natural selection is the process that explains how species can change (evolve) over generations of time. Organisms with favorable traits are more likely to survive and reproduce. In doing so, they pass on helpful traits to the next generation. Over generations of time this process allows organisms to adapt to their environment. This is because the favorable traits will increase in the population over generations of time. At the same time, organisms that are poorly adapted to their environment die off and are less likely to pass on their "unfavorable" traits to future generations.
*Keep in mind* the process of natural selection completely depends on the environment (which changes!).
The Process of Natural Selection
Natural selection is often a misunderstood but actually very simple process that causes populations of living things to change (evolve) over time. In fact, it is so simple that it can be broken down into five basic steps: Variation, Inheritance, Selection, Time and Adaptation or "V.I.S.T.A." for short.
Variation
Members of any given species are rarely exactly the same, either inside or out. Organisms of the same species can vary in size, coloration, ability to fight off diseases, and countless other traits. Such variation is often the result of random genetic mutations, or "copying errors," that happen when cells divide as new organisms develop. Variations can occur both randomly and as a result of a trait being more fit (adapted) for a particular environment.
|
According to a scientific study, when parents pass their genes down to their children, an average of 60 errors or genetic mutations are introduced to the genetic code in the process (source).
|
Inheritance
Inheritance is the process by which genetic information is passed on from parent to child. This is why members of the same family tend to have similar characteristics. When organisms reproduce, they pass on their DNA- (set of instructions in living cells) to their offspring. And since many traits are encoded in DNA, offspring often inherit the variations of their parents. Tall people, for example, tend to have taller children.
|
Selection
Environments cannot support unlimited populations of organisms. This is because resources available in any environment are limited. Essentially more organisms are born than can survive: some individuals will be more successful at finding food, or avoiding predators and will have a better chance to survive, reproduce, and pass on their DNA and thus "selected for" in that particular environment. Differences in color, for instance, help some individuals in camouflaging themselves from predators. Sharper eyes and claws help an owl catch its dinner.
|
Time
Generation after generation, helpful traits will allow some individuals to survive and reproduce better than others. These traits are then more likely passed on to greater and greater numbers of offspring. After just a few generations or after thousands, such traits become more common in the population. This causes the population to change (evolve) over time.
The process of natural selection has been directly observed in nature and has been demonstrated in a scientific lab countless times. |
Adaptation
The result is a population becomes better suited--or better adapted--to some aspect of the environment than it was before. Legs once used for walking are modified over many generations for use as wings or flippers. Scales used for protection change colors to serve as camouflage. Or, in this case bugs that taste really bad become more common in a population over generations of time.
Remember! "Adaptations take Generations." Adaptations do not arise within a single generation. For example, Giraffe's do not get long necks in their lifetime. It took generations of time. |
Example: How Natural Selection can work:
Let's do a simplified, example: Let's say a population of mice with variation in fur color (black vs. tan) has just moved into a new area where the rocks are black in color. This environment has hawks, which like to eat mice and can see the tan mice more easily than the black ones against the black rock.
Because the hawks can see and catch the tan colored mice more easily, a relatively large number of the tan mice are eaten, while a smaller number of the black mice are eaten. The black mice (in this particular environment) are more likely to pass on their traits. Over many generations the population of mice will evolve to be more dark in color compared to the starting population.
|
Artificial Selection?
Artificial selection is the intentional breeding of plants or animals. It means the same thing as selective breeding and is an ancient method of genetic engineering.
Selective breeding is a technique used when breeding domesticated animals, such as dogs, pigeons or cattle. Some of these animals may have traits that a breeder will want to carry over to the next generation. The breeder will therefore "select" those animals to breed which have that quality, rather than those that do not.
|
Video Guide:
|
|
Topic Tips
- Populations in a particular environment that have adapted to living conditions in that specific area are therefore better able to meet their survival needs and are more likely to survive and reproduce offspring with those key survival traits and can change over time by the process of natural selection.