6.2.2 Evolution

In this lesson, we will explore the concept of evolution, focusing on the process of natural selection and its role in shaping the characteristics of populations over time.

Natural Selection and Evolution

Evolution is defined as a change in the inherited characteristics of a population over successive generations. It involves the accumulationChange in a physical quantity over time, whether that be an increase, decrease, or no change at all. of small changes in the genetic makeup of a population, leading to the emergence of new traits and the potential formation of new species.

• Theory of Evolution by Natural Selection: The theory of evolution by natural selection, proposed by Charles Darwin, explains how species change and adapt over time. It states that variations exist within populations, and those individuals with traits that are advantageous for their environment have a higher chance of survival and reproduction.
• Variants and Phenotypes: Genetic variation within a population leads to the presence of different phenotypes (observable traits) among individuals. Some phenotypes may be more favourable for survival and reproductive success in a specific environment.
• Natural Selection Process: Natural selection acts on these variants by favouring individuals with traits that increase their fitness (reproductive success). These individuals are more likely to pass on their advantageous traits to future generations, resulting in an increase in the frequency of those traits within the population.
• Adaptation and Survival: Over time, the accumulation of advantageous traits through natural selection can lead to the adaptation of populations to their specific environments. This process enhances their ability to survive and reproduce in changing conditions.

Speciation

• Formation of New Species: If two populations of a species become so genetically distinct that they can no longer interbreed or produce fertile offspring, they are considered to have formed two new species. This reproductive isolation is a key factor in the development of biological diversity.
• Divergent Evolution: Divergent evolution occurs when two populations of a common ancestor undergo natural selection under different environmental conditions, leading to the development of distinct traits and adaptations. Over time, these populations may accumulate enough genetic differences to become separate species.

Conclusion

Evolution is a fundamental process that explains the diversity and complexity of life. Through natural selection, populations gradually change and adapt, leading to the formation of new species over long periods of time. Understanding the theory of evolution by natural selection allows us to appreciate the interconnectedness of all living organisms and provides insights into the patterns and mechanisms that drive the development and survival of life on Earth.