Adaptation

An adaptation is an inherited feature that makes an organism better suited to its environment. It can help the organism survive or reproduce, increasing its reproductive success: the chance of producing offspring that themselves survive and reproduce.

An adaptation is useful in relation to a particular environment. For example, a feature that reduces water loss can be advantageous where water is scarce, but may offer little advantage where water is plentiful. If the environment changes, a feature that was once advantageous may become less useful.

Types of adaptation

Adaptations can be grouped according to the kind of feature involved:

• Anatomical adaptations are body structures. For example, a thick, waxy surface on a plant can reduce water loss.
• Physiological adaptations are internal processes. For example, producing concentrated urine allows some animals to conserve water.
• Behavioural adaptations are inherited patterns of action. For example, being active mainly at night can help some desert animals avoid the heat of the day.

Adaptation and natural selection

Individuals in a population can inherit different versions of genes, called alleles. Some of these differences affect features that influence reproductive success in the environment.

If an inherited feature gives its bearers an advantage, they are more likely to reproduce and pass on the alleles associated with it. Over generations, those alleles can become more common in the population. This process is natural selection. As a result, the population can become better adapted to its environment.

Adaptations do not appear because an individual needs them, and individuals do not change their inherited features simply by trying to adapt. Natural selection acts on inherited differences already present in a population.

Changes in inherited characteristics across generations are part of evolution. Because different environments favour different features, adaptation through natural selection contributes to the diversity of living organisms.

Adaptive features

An adaptive feature is an inherited characteristic that helps an organism survive or reproduce in its environment. It may help the organism deal with a particular condition or make use of a resource it needs.

Whether a feature is adaptive depends on the conditions the organism faces. For example, thick fur can help a polar bear survive in a cold environment by reducing heat loss. The explanation connects the feature to a condition and then to a benefit for survival; simply saying that the bear has thick fur does not explain why the feature is adaptive.

Identifying an adaptive feature

An image or other information about a species can suggest a possible adaptive feature. To describe it as adaptive, identify the feature, the relevant environmental condition, and how the feature helps the organism survive or reproduce there.

An image may show a characteristic, but it does not by itself establish that the characteristic is inherited or that it is beneficial. Other information may be needed to support those claims.