Evidence from Fossils Sequence fossils appear matches the
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Evidence from Fossils • Sequence fossils appear matches the sequence they would evolve • Age of fossils determined from age of rock • Bac t. , algae, fungi , worms, land vetebrates • Bony fish, amphibians, reptiles, birds, placental mammals • Plants before animals, land plants before land animals, flowering plants before insects • Many sequences link existing organisms to ancestors
Evidence from selective breeding • Large differences between modern livestock and wild species • Variation between domesticated breeds • Humans selectively breed animals for specific traits that they consider useful. This process is called artificial selection • Artificial selection causes large changes in a short period of time. • Selection causes evolution
Analogous Structures • Structures that have different origins but become similar because they perform the same or a similar function. Result of Convergent evolution. • Wings of birds and butterflies • Tail fins of whales and fishes • Unrelated species evolved similar features out of necessity
Evidence of Homologous structures • Structures that look different and may form a different function, but have a “unity of type. ” • Forelimbs of human, mole, horse, porpoise, and bat • Same bones in same positions. • All share common ancestor that had a pentadactyl limb. • Limbs have become different because they perform different functions. • Adaptive Radiation
Vestigial Structures • Reduced structures that show no particular function • Developing teeth in whale embryos when adult whales have no teeth • Small pelvis and thigh bone in whales and some snakes • Appendix in humans. • Structures that no longer have a function and are eventually being lost by evolution
Pentadactyl Limb Bone Structure Forelimb Hindlimb Single bone in the proximal part Humerus Femur Two bones in the distal part Radius and ulna Tibia and fibula Group of wrist/ankle bones Carpals Tarsals Series of bones in each of 5 digits Metacarpals and phalanges Metatarsals and phalanges
Speciation • Populations of a species become separated so they cannot interbreed. • Natural selection acts differently on each of the two populations • Species evolve in different ways. • Characteristics gradually diverge and become recognizably different • Species no longer capable of interbreeding • Often occurs if species become geographically isolated
Charles Darwin • Young naturalist explored the Galapagos Islands located off the western coast of South America • Noticed on the islands numerous different organisms • Finches: differences in the size and shape of their beaks
Evidence from Patterns of Variation • Divergence is gradual • Organisms present at different stages of divergence • Red Grouse of Brittain and Willow Ptarmigan of Norway • Sometimes classified as same species, sometimes not. • Darwins Finches
The Red Grouse and the Willow Ptarmigan where at one time classified as two separate species. The current scientific consensus is that they are both members of the same species (Lagopus lagopus) Populations will gradually diverge over time and it is natural to see continuous variation across a geographical range. The greater the geographical separation and the longer http: //en. wikipedia. org/wiki/File: Ptarmigan 9. jpg http: //en. wikipedia. org/wiki/File: Lagopus_lagopus_Alaska_2. jpg the populations have been separated the greater the http: //www. wildaboutbritain. co. uk/gallery/files/9/2/4/DSC_0014 copy. jpg divergence. http: //www. western-isles-wildlife. com/photogallery/Red%20 Grouse%20 Lewis%2008%20 crop. jpg
Industrial Melanism • Melanistic- dark varieties of typically light-colored insects • Melanistic varieties more common in polluted, industrial areas • In unpolluted areas, light colored insects are better camouflaged. • In polluted areas, dark colored insects are better camouflaged. • Example of evolution by natural selection
- Glacial evidence of pangea
- Indirect fossil
- How is the fossil record evidence for evolution
- Fossils as evidence of continental drift
- Fossils evidence of past life
- Class vs individual evidence
- Primary evidence vs secondary evidence
- Explain how class evidence can have probative value
- Primary evidence vs secondary evidence
- Primary evidence vs secondary evidence
- Class evidence vs individual evidence
- Primary evidence vs secondary evidence
- Why are fibers class evidence