Evolution: Evidence, Factors, Population

Evolution: the irreversible, historical development of living nature.

The driving forces of Charles Darwin's theory: heredity, variability, the struggle for existence and natural selection. His Darwin's work: On the Origin of Species.

1. Variability and heredity
2. Struggle for existence
3. Natural selection
4. Adaptation, new species

Evidence for evolution

• Paleontological: fossil remains, transitional forms. Archaeopteryx: between reptiles and birds, that is, between reptiles and birds.
• Comparative anatomical: homologous organs, vestigial organs and atavisms.
• Embryological: the biogenetic law of Müller and Haeckel.
• Biogeographical and molecular-genetic evidence.

The elementary unit: the population.

Evolutionary factors: the mutation process, population waves, isolation, genetic drift and natural selection.

Key facts

Organ	Meaning	Example
Homologous	same origin, different function	bird wing and horse forelimb
Analogous	same function, different origin	butterfly wing and bird wing
Vestigial	an organ passed down through generations that has remained underdeveloped	the appendix (vermiform process) and the tailbone in humans
Atavism	reappearance of a trait typical of ancestors	a child born with a tail

• Homologous: same origin, different function. Analogous: same function, different origin.
• Vestigial organ: the appendix in humans (vermiform process) and the tailbone.
• Hardy-Weinberg: p² + 2pq + q² = 1. In an ideal population, allele frequencies do not change.
• Forms of selection: driving (directional), stabilizing, disruptive.
• The directing factor: natural selection.