Mechanisms of Biological Evolution and Genetic Adaptation

Understanding the Process of Biological Evolution

Evolution is a gradual process that leads to the emergence of new species and causes adaptations. It accounts for the diversity of species originating from a common ancestor and is responsible for the appearance of new species.

Theories of Evolution

Evolutionary theories describe self-organizing processes occurring in living systems. Different schools of global thought exist to explain the processes through which living beings evolve.

Lamarck's Evolutionary Scenarios: Transformism

In this model, species transform gradually as one evolves into another. This theory is based on the principle that "the function creates the organ": organisms adapt, causing transformations through habit. Organs develop with use and atrophy when they are not used. This leads to the inheritance of acquired characters, where new traits are passed to descendants, resulting in gradual transformations from pre-existing species.

Lamarckism Error: Acquired characters are not inherited by descendants; only characters located in the gametes are inheritable.

Darwin's Theory of Evolution

This theory challenged fixism, which argued for the stability of species. Developed by Charles Darwin and Alfred Wallace, it was popularized in the book The Origin of Species by Means of Natural Selection. The theory uses natural selection to explain the evolutionary mechanism:

• Competition: To replace those that die, the population size remains constant over time.
• Variability of populations: There is variability between heritable characteristics.
• Natural selection: As a consequence of competition, individuals with advantageous characters manage to survive to maturity and mate, inheriting favorable traits.

Species evolve: In the next generation, advantageous changes accumulate in the population, giving rise to new forms.

Neo-Darwinism and the Synthetic Theory

Evolution is a phenomenon of populations, where the present gene variability allows natural selection to act. This Synthetic Theory combines Darwinian natural selection with Mendelian genetics and chromosomal inheritance, leading to the field of population genetics.

Principles of Neo-Darwinism

A population consists of all individuals of the same species. The gene pool is the sum of all genetic variation; each genotype is slightly different, and some mutations exist only in certain individuals. This random process is caused by mutations and genetic recombination. Mutations are the primary cause of natural selection and genetic variability. The evolutionary process ensures that each population becomes better adapted to its environment.

Natural Selection and Evolutionary Success

Using the example of moth mutations, these changes occur randomly; each evolutionary step exists by chance.

Agents of Natural Selection

These agents establish competition. Relationships between predators and prey act as agents of natural selection, driving adaptations and, in some cases, extinctions.