AP Bio unit 7.6-7.7 - Evidence of Evolution and Common Ancestry

Overwhelming evidence supports the theory of evolution.
Primary sources of evidence include:
- Fossil Record
- Comparative Morphology
- Biogeography

Fossils: Remains or traces of past organisms that provide insights into evolutionary changes over time.
- The fossil record helps visualize these changes.
- Fossils can be dated by examining the rate of carbon-14 decay and the age of surrounding rocks.
- Provides geographical context for the organisms discovered.

Comparative Morphology: The analysis of the structures of living and extinct organisms.
- Homology: Characteristics in related species showing similarities despite differing functions.
  - Embryonic Homology: Many species exhibit similar embryonic development stages.
  - Vestigial Structures: Features retained in organisms that have lost their original function.
    - Examples: Tailbone and appendix in humans.
  - Molecular Homology: Similar DNA and amino acid sequences shared among species, indicating common ancestry.
- Homologous Structures: Similar characteristics in two species due to a shared common ancestor.
  - Example: Arm bones in mammals (humans, whales, bats).

Convergent Evolution: Independent evolution of similar adaptations in distantly related organisms from similar environmental pressures.
- Analogous Structures: Traits that appear similar but do not arise from a common ancestor.
  - Example: Wings in birds, bats, and insects (bees) - similar function but different evolutionary origins.

Structural evidence indicates a common ancestry for all eukaryotes.
- Conservation of fundamental cellular features across organisms, such as:
  - Membrane-bound organelles
  - Linear chromosomes
  - Presence of introns in genes

Biogeography: The geographical distribution of organisms (plants and animals).
- Example 1: Species on oceanic islands often resemble those on the mainland, indicating shared ancestry.
- Example 2: Species on the same continent show similarities and differences from species on other continents, reflecting evolutionary processes.

Types of data providing evidence for evolution include:
- Fossil Data
- Biogeography
- Morphological Data
Structures become vestigial through natural selection when:
- A structure may have been beneficial at one time but becomes useless due to mutations, leading to conservation across generations without being selected for or against.