🌱

Understanding Evolution and Natural Selection

Jun 4, 2025

Evolution

Causes of Species Change (Evolution)

  • Variation: Changes found in a species.
  • Mutation: Random changes in DNA.
  • Overpopulation: Overproduction of a species that the environment cannot sustain.
  • Competition: Struggle for resources; traits that confer advantage win out.
  • Inheritance: Traits are passed from parent to offspring.
  • Environmental Change: Leads to natural selection.

Mutation and Environment

  • The environment does not directly cause mutations.
  • Mutations exist prior, but environmental changes can cause certain mutations to become more prevalent through adaptation.

Key Definitions

  • Evolution: Gradual change in species' characteristics over generations due to natural selection and environmental changes.
  • Homologous Structures: Features found in different species that share a common evolutionary ancestor.
  • Fossil: Preserved remains or traces of past life, typically found in sedimentary rock.
  • Embryology: Study of organisms before birth.
  • Adaptation: Inherited trait that enhances survival of a species.
  • Natural Selection: Process where organisms with traits best suited to the environment survive and reproduce.

Homologous Structures as Evidence for Evolution

  • Show similarities between organisms, indicating a common ancestor.

Types of Evidence Used by Scientists

  1. Comparative Anatomy: Fossils and homologous structures.
  2. Embryology: Study of development before birth.
  3. Molecular Biology: Genetic analysis to understand evolutionary links.

Role of Variation in Natural Selection

  • Variation enables species survival through adaptation.
  • Allows species to evolve by selecting for the best traits.