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.