5.3 Evidence of Evolution
2026-05-18 18:54
Status: #new
Tags: #biology #evolution
Evidence of Evolution
Evolution by Natural Selection
- Evolution is the change in inherited traits in a population from generation to generation
- Natural Selection states individuals better adapted to their current environment have a higher fitness, where they are more likely to pass on their alleles to next generation
- Natural Selection also ensures that a population is better adapted to the environment over time, and harmful alleles will appear less.
Proof of Evidence by Natural Selection
- There are 5 Key Pieces of Evidence that support's Darwin's theory of evolution by natural selection
Fossil Record
- Extinctions prove that species have appeared and disappeared on the Earth over different time periods
- Darwin used the existence of extinct animal fossils to state that organism that aren't well adapted to their environment will die off.
- In some cases - Fossils share similarities to living organisms
- 13% of all invertebrate species have become extinct in the last 500 years
Fossil Records support evolution through
- Providing evidence living things have evolved
- Showing history of life on Earth and how different groups of organism have change over time
- ie. Fossils in younger layers of rock are alot more similar to fossil species found alive today.
Transitional Fossils
- Shows phenotypes of ancestral and descendant species, showing there is evolutionary changes between them.
Lost Structures
- Appendages may be lost over time. Structures once useful but no longer are considered vestigial.
- These show that changes in populations DO happen to yield evolution
Human Vestigial Features
- Ear Muscles - Muscles attached to the ear that CANNOT move it..
- Wisdom Teeth - Useful for grinding down plant tissue (no longer needed)
- Tail bone - The remnants of a lost tail...
- Palmaris Longus Muscle - An absent muscle tendon in the arms...
Burgess Shale Formation
- Location of one of the worlds most diverse fossil treasures
- Rich in Soft Tissue (undecomposed organism matter) Fossils
Biogeography
- The study of the past and present geographical distribution of a species of population
- A key evidence is that geographically (or once geographically) adjacent regions share similar species
- Evolution explains why isolated islands have so many unique species
Darwin's Finches
- An ancestral finch population was blown off from Mainland South America onto the Galapagos Islands. The finch species over time evolved to fulfill all the niches on the islands, and gave rise to the variety of finches seen on the islands.
Anatomy
Homologous Structures
- When there is similar physical features between organisms with a common ancestor, but their features serve different functions.
- This supports evolution by showing that groups of organism are all related to each other and come from a common ancestor that inhibited various new environments and evolved to adapt to said environments.
Analogous Structure (Opposite of Homologous)
- Different organisms sharing similar physical features that are NOT the result of evolution from a common ancestor. (They diverge in physiology)
- Supports evolution through convergent evolution, the idea that many species share similar physical traits yet are not closely related.
- Other Interpretation:
- Organisms show similar adaptations to a similar environment
Carcinization
- Organisms evolving towards a "crab-like" structure
Embryonic Development
- An organism in its embryo stage follows its evolutionary history.
- Supports evolution by proving there is commonalities in development between similar groups of organisms
Biochemical/DNA/Proteinevidence
- Through examination of DNA sequences or order of Amino acids in a protein, scientists could create a hypothesis of how closely related two organisms could be.
- This supports evolution by provision of genetic evidence of evolution, similar allele structures, chromosomes etc.