Life has existed on Earth for millions of years. Living forms and creatures have inhabited almost all of Earth and over the years have changed and transformed from the way they existed many years ago. This transformation and modification in features and functions in living beings is called evolution – though it is believed that a few creatures, like the modern cockroach and the crocodile, have not changed since the era of dinosaurs.

Evolution is a process that results in changes in the genetic material of a population over time. Evolution reflects the adaptations of organisms to their changing environments and can result in altered genes, novel traits, and new species. Evolutionary processes depend on both changes in genetic variability and changes in allele frequencies over time.

The study of evolution can be performed on different scales. Microevolution reflects changes in DNA sequences and allele frequencies within a species over time. These changes may be due to mutations, which can introduce new alleles into a population. In addition, new alleles can be introduced in a population by gene flow, which occurs during breeding between two populations that carry unique alleles. In contrast with microevolution, macroevolution reflects large-scale changes at the species level, which result from the accumulation of numerous small changes on the micro-evolutionary scale. An example of macroevolution is the evolution of a new species.

One mechanism that drives evolution is natural selection, which is a process that increases the frequency of advantageous alleles in a population. Natural selection results in organisms that are more likely to survive and reproduce. Another driving force behind evolution is genetic drift, which describes random fluctuations in allele frequencies in a population. Eventually, genetic drift can cause a subpopulation to become genetically distinct from its original population. Indeed, over a long period of time, genetic drift and the accumulation of other genetic changes can result in speciation, which is the evolution of a new species.

Credit: Scitable by nature education

Picture Credit: Quanta Magazine

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