Defining Biological Evolution
Biological evolution is the cumulative change in the heritable characteristics of biological populations over successive generations. It is not about an individual changing during its lifetime, but rather about changes in the frequency of genes and traits within a population over many generations.
Core Mechanisms of Evolution
The primary mechanisms driving evolution include natural selection, which favors traits enhancing survival and reproduction; genetic drift, random changes in gene frequencies; mutations, new variations arising from changes in DNA; and gene flow, the movement of genes between populations. These forces interact to shape the genetic makeup of populations.
A Practical Example: Antibiotic Resistance
A clear example of evolution in action is the development of antibiotic resistance in bacteria. When antibiotics are used, susceptible bacteria die, but those with genetic mutations that confer resistance survive and reproduce. Over time, resistant strains become more common in the population, demonstrating a measurable evolutionary change.
Importance in Biology and Beyond
Understanding evolution is crucial for comprehending the diversity of life on Earth, predicting how species might adapt to environmental changes, and developing strategies in medicine, such as fighting disease or creating new vaccines. It provides a foundational framework for nearly all biological sciences.