Definition: Natural selection is the process where organisms with beneficial traits have higher survival and reproduction rates, leading to the accumulation of advantageous characteristics in populations.

Example: Genetic drift can be observed in small island populations where certain traits become more common due to random chance rather than adaptive advantage.

Vocabulary: Gene flow describes the transfer of genetic material between populations through migration or interbreeding, contributing to genetic diversity.

Highlight: Mutations serve as the ultimate source of genetic variation, providing the raw material for evolution through spontaneous DNA sequence changes.

Definition: Fossils are preserved remains or traces of ancient organisms found in sedimentary rock or other materials, providing direct evidence of evolutionary changes over time.

Example: Homologous structures, such as the wing of a bat and the arm of a human, demonstrate common ancestry despite serving different functions in modern species.

Vocabulary: Biogeography refers to the study of how organisms are distributed geographically across the Earth, providing insights into evolutionary patterns and species relationships.

Highlight: Molecular biology, particularly DNA and RNA analysis, offers the most precise evidence of evolutionary relationships between species through genetic sequence comparisons.