Difference Between Natural Selection and Adaptation in Evolution

In 1859, the term ‘evolution’ was mentioned for the first time in a book by Charles Darwin called ‘The Origin of Species’. The concept of evolution was introduced to the world by Darwin during his journey to the Galapagos Islands. In this journey, he took notice of the living organisms and observed that all the living species change both their physical and anatomical structure over extended periods of time to adapt better to the developing environment. The living species that fail to adapt and adjust to the changing environment eventually cease to exist. This was the concept by Darwin and he called it the ‘Survival of the fittest.

Let us discuss some details about natural selection and adaptation before discussing ‘what is the difference between natural selection and adaptation?’. Both natural selection and adaptations are part of the evolution of the species.

Biological Evolution

Evolution, basically, is a scientific theory that is used by biologists at large to explain the process of how the living species change in their characteristics for their better adaptations to the changing environment. It is the successive adjustment to changing environment by inherited traits over a huge period, over generations. Researchers describe evolution as not only the process but also as an outcome of a process. It helps to build up a mind map of how Earth came into being. 

Natural Selection

Natural selection is a process in which living organisms adapt and change. However, all individuals in the population are naturally variable. The change that occurred by natural selection is a heritable trait of a population over generations. Natural selection is the key mechanism of evolution.

Biodiversity is very closely related to evolution as it is the result of the various processes that come under evolution. The concept of natural selection is one such process among others. According to the Darwinian theory of evolution, natural selection resulted in evolution. It states that natural selection is biased against the inherited characters of organisms. The ability of organisms to adapt is the one that helps organisms in evolution through the process of natural selection. 

Natural selection is classified in different ways depending on the following factors. 

• Effect on the trait 

• The effect on genetic diversity

• Lifecycle state 

• Unit of selection

• Resources being competed for

Adaptation

Adaptation is an evolutionary process that helps organisms to fit in their environment. It is generally a process not a Physical state of change. The adaptation was described in ancient times by Greek philosophers like Aristotle and Empedocles. Adaptation is a continuous process that does not have a final form.

Adaptation can be defined as an organism’s physical or behavioural characteristic of an organism that helps the organism to survive better in the surrounding environment. The living species survive when they adapt to their living habitats. This happens because living organisms have special features that enable them to adapt and survive in changing environments. The processes of evolution due to gene mutation result in the development of these special features. The process of gene mutation helps in survival and reproduction and is transferred from one generation to another. 

Adaptation is majorly discussed in Philosophy of Biology, and it is related to Biological fitness. There are different types of adaptations that are discussed below. Take a look here:

• Structural adaptations: It is a physical feature of the organism, eg: Fur on a Bear, camouflage, found in some organisms, is a colouration that provides the organisms with the ability to blend into its environment. 

• Behavioural adaptations: This is something that an organism does to survive and reproduce.  This behaviour change occurs due to the changes in the surrounding environment of the organisms or because of changes in the inactions of other species. For ex: a rabbit comes into a still motion when it senses a predator around. Changes in reproductive strategy, feeding habits, migration, communication, hibernation are also examples of behavioural adaptations.

• Physiological adaptation: It is the way in which an organism responds to the stimuli in the environment. It is very much similar to structure adaptation as both of these adaptations involve physical changes in the species. Physiological adaptations, however, are not always visible in living organisms’ physical appearance. The cause of this type of adaptation is either due to the changes in the behaviour of other species or changes in the environment. Forex: when the water becomes more acidic, a fish living in that water has to shift its chemistry to adapt to the surroundings.

• Co-adaptation: This will occur in two or more interacting species for mutual benefit. 

• Mimicry: It is the superficial resemblance of other organisms which are not closely related. It helps to save the living organism from predators and survive.

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The above Diagram is an example of adaptation. The plant is Ophrys apifera (Bee orchid) which uses Pheromones to attract male bees. It is designed in such a way that, in attempting to copulate with the flower, pollen adheres to the insect’s body.

What is the Difference Between Natural Selection and Adaptation?