Relics or impressions of organisms from the past. › Show changes over time from simple to complex....
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Transcript of Relics or impressions of organisms from the past. › Show changes over time from simple to complex....
Evidence of Evolution
Early Evidence of Evolution =
1. Fossils
Relics or impressions of organisms from the past.› Show changes over time from simple to
complex.› Many fossils don't have descendants.
Fossil Record
Most fossils found in sedimentary rock Due to aquatic
preservation, fossils remain largely intact and fossilize in layers
Rock forms in layers, or strata Often sand or silt is
deposited on top
existing layer, compacting it into rock
Fossil Record
Limited:1. Type of material
preserved (bone, shell, impressions, amber)
2. Incomplete record3. Easily disrupted
Evolution Relevance
Life has changed over time.
Many species failed to survive and became extinct.
Law of Superposition- Fossil Record is
formed due to the layering
- Older rock is “lower” than younger rocks
- Fossils help show what organisms have similarities or dissimilarities
Comments1. Fossilization is a rare event.2. Only hard parts fossilize well.3. Problem in finding fossils.4. Interpretation.5. Missing Links.
2. Homology
Evidence for evolution: used with fossils and current species
Homologous Structures - Same structure, different function
Mammal forelimbs
3. Vestigial structures structures that have a major function in one
organism, but less in another ex: whale limbs. ostrich wings
› Evidence for descent
from common ancestor
4. Comparative Anatomy:
Structural similarities link related species
5. Development (Embryology)
Developing embryos of different organisms appear similar during maturation.
Distinctive differences occur later in the process
Comparative embryology:Similar embryo development in closely related species
6. Biogeography
The geographical distribution of species.Some animals in South American tropics
share similarities with African desert animals rather than African tropical animals
Australia is home to more marsupial animals than anywhere else in the world, and had relatively few placental animals.
7. Plate Tectonics How the continents moved Supports evolution by looking at
which species used to be close to each other geographically
8. Molecular Biology
In the era of DNA –
- The closer the DNA sequences, the closer related› The less the sequences match, the further
the relationship› Humans and Chimps 98% similar genes› Humans and Mice 70-80% similar genes