Flashcards in Evolution 5.1 Evidence for Evolution Deck (18)
What is a species?
A species is a group of organisms that share common physical characteristics
Members of the same species are capable of breeding together to produce viable offspring
What is evolution?
Evolution is the cumulative change in the heritable characteristics of a population
What happens in speciation?
Evolution can lead one species to diverge into two separate species. One species can gradually diverge into separate species by evolution
What do fossils tell us about evolution?
- Fossils demonstrate gradual change in physical characteristics of a species
- Fossils demonstrate species extinction
Fossils record the gradual change in the characteristics of a species over long periods of time
What is a homologous structure?
A homologous structure is a physical characteristic shared by related species
What does the pentadactyl limb tell us about mammals?
All mammals are descended from a common ancestor
The genetic code is universal.
This provides evidence that all living species share common ancestors.
Outline the difference between artificial and natural selection.
Organisms are selected for a purpose (better tasting food crops, smarter sheepdogs, faster racehorses)
Artificial selection is carried out by humans
Organisms are not selected for a purpose… instead the focus is on survival
Natural selection is driven by environment
Outline a basic procedure for artificial selection
1. Test on which frogs jump the furthest
2. Breed the best jumping frogs
3. Wait for the offspring to grow up, then test them.
4. Repeat steps 2 and 3 for many generations
How does artificial selection demonstrate evolution?
Selective breeding of domesticated animals (pets) shows this because they have evolved through human selection
What is a cline?
A cline is a gradation in one or more characteristics within a species.
Outline five types of evidence which support the
theory of evolution by natural selection
? fossils/paleontological: fossilized horse ancestors/other evidence
? homologous structures: pentadactyl limb/vertebrate embryos/other
? Selective breeding of domesticated animals shows that artificial selection can cause evolution
? recent observed evolution: resistance to antibiotics/melanistic (dark color) insects in polluted areas/other recent example
? geographic distribution: ring species/other evidence from geographical distribution
? biochemistry: cytochrome c/other biochemical evidence
What explains similarities in structure when there are different function?
Evolution of homologous structures by adaptive radiation explains the similarity even when they have different functions.
What is adaptive radiation?
When organisms come from the same origin, like from an ancestor that had a pentadactyl limb, and they become different because they perform different functions.
What is a convergent evolution?
Organisms that have had different origins and have become similar because they perform the same or a similar function.
Give evidence from patterns of variation.
Example: human skin colour as evidence for evolution:
• People with darker skin colour have evolved in places with high UV light --> protect them from cancer
• People with lighter skin colour have evolved in places with low UV light --> helps them to generate enough Vitamin D
What is gradual divergence?
Continuous variation across the geographical range of related population matches the concept of gradual divergence.
Does the continuous range in variation match the belief that species were created as distinct types of organisms?
No it does not. Continuous range in variation is not constant or unchanging.
It provides evidence for evolution and origin of species by evolution.