TLDR: Adaptation is the process where organisms change to fit their environment, either through physical traits or behaviors. It is a result of natural selection and helps organisms survive and reproduce.
Adaptation is a concept in biology that has three main meanings. First, it is the process of evolution through natural selection that helps organisms fit into their environment and improve their chances of survival and reproduction. Second, it is the state that a population reaches during this process. And third, it refers to specific traits or characteristics that have evolved and are beneficial for individual organisms.
Throughout history, adaptation has been studied and discussed by philosophers and natural historians. In the past, it was often seen as evidence for the existence of a deity. However, Charles Darwin proposed that adaptation was explained by natural selection, a process where organisms with advantageous traits are more likely to survive and pass on their genes.
Adaptation is closely related to biological fitness, which determines the rate of evolution. Sometimes, two or more species co-adapt and co-evolve as they develop traits that work together, such as flowering plants and pollinating insects. In mimicry, species evolve to resemble other species for protection or other benefits. Features that evolved for one purpose can also be co-opted for a different purpose, like the feathers of dinosaurs being used for bird flight.
Adaptation is a major topic in the philosophy of biology, as it involves the function and purpose of traits. Some biologists prefer to avoid using terms that imply purpose in adaptation, while others argue that adaptation is necessarily purposeful.
In terms of history, adaptation has been recognized by ancient Greek philosophers like Empedocles and Aristotle. It was also interpreted as the work of a deity in natural theology. However, Darwin and other scientists emphasized the flaws and limitations in the natural world, challenging the idea of perfect adaptation.
Adaptation can occur through changes in habitat, genetic changes, or a combination of both. When a habitat changes, organisms may move to more suitable places, a process known as habitat tracking. Genetic changes, such as mutations, can also lead to adaptation. For example, the beak shapes of Darwin's finches are driven by adaptive mutations in specific genes.
Adaptation is not the same as flexibility, acclimatization, or learning. Flexibility refers to an organism's capacity to maintain itself in different habitats, while acclimatization involves physiological adjustments during an organism's lifetime. Learning refers to improvements in behavior through experience.
There is a relationship between adaptedness and fitness, which is a measure of an organism's ability to survive and reproduce. However, a phenotype with high adaptedness may not always have high fitness. Adaptation is an ongoing process, as habitats and biota are constantly changing.
In summary, adaptation is the process by which organisms change to fit their environment, either through physical traits or behaviors. It is a result of natural selection and helps organisms survive and reproduce.