Evidence for Evolution Flashcards
Main evidence of evolution
- Comparisons of existing animals and plants
- Fossilised remains of animals / plants million years ago
- DNA of existing animals / plants
- Geographical distribution of species
Pattern of Divergent Evolution
- One ancestral species becomes two or more new species
- Species live in different environments, with different selection pressures.
- Evidence: homologous structure
What is homologous structure?
They have same Origin but different function.
Pattern of convergent evolution
- Two or more unrelated species evolve to become more similar to each other.
- Species live in similar environments, with the same selection pressures. But they can NEVER merge to become one species.
-Evidence: Analogous structure
-E.g. Vertebrate forelimbs
Evidence of convergent evolution
Analogous structures
Evidence of divergent evolution
homologous structure
What is analogous structure?
have different structure and origin but the same function.
What is analogous structure?
- The ability to fly, evolved independently
What are bird wings supported by？
Bones
What are bee wings supported by?
Strong fibres
Difference between homologous and analogous
H: Same structure and Origin, different function.
A: different structure, same function
Evidence from fossils
Rock layers reveals differences in the fossils contained each year, oldest rock / fossils at the bottom, youngest at the top.
What is the sequence of fossils
- Plant fossils appear before animal fossils
- Plants on land appear before animals on land
- Plant suitable for insect pollination appear before insect pollinators
Evidence from DNA - DNA sequence
DNA sequence from two species are very similar, then they are closely related.
Evidence from anatomy
Similarities and differences in the body structures of different species
