Evolutionary Biology: From Lamarckism to Neo-Darwinism

Understanding Lamarckism

• The need to adapt: Physical features of plants and animals change to adapt to environmental pressures.
• The law of use and disuse: Lack of constant use weakens body faculties, eventually causing them to disappear.
• The law of inheritance of acquired characters: Nature preserves traits that individuals have acquired or lost.

Although Lamarckism is considered an incorrect theory, it opposed the ideas of fixed species and provided the first reasoned explanation for evolutionary changes.

Darwin and Wallace's Theory

• Populations consist of individuals that show variations.
• Some of these variations are transmitted to offspring.
• In each generation, only a portion of the population survives to reproduce.
• Individuals who survive and reach reproductive age are the most suitable.
• Natural selection is the survival and reproduction of the fittest individuals.

Paleontology: The Study of Fossils

Paleontology is the scientific discipline dedicated to the study of fossils. Fossils are remains of organisms from other eras that have been preserved in the Earth's crust by natural causes.

The Evolution of Darwinism: Neo-Darwinism

• Genes: Units of genetic information composed of DNA that determine hereditary traits. Mutations are the primary cause of variability.
• Natural selection: Acts on variability and is responsible for the gradual evolution of species.
• Species: A group of morphologically similar individuals capable of reproducing to produce fertile offspring.
• Isolation: Reproductive or geographic isolation is a key factor in speciation.

Symbiogenesis

The phenomenon of symbiosis is common in nature and occurs in both animals and plants. Mitochondria (energy producers) and chloroplasts (responsible for photosynthesis) originated from bacteria that participated in the formation of the first eukaryotic cell, which is a cell with a distinct nucleus.