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Artificial Selection aka Selective Breeding
Darwin noted that plant and animal breeders would breed only the largest hogs, the fastest horses, or the cows that produced the most milk.
Darwin termed this process artificial selection or selective breeding.
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Evidence of Evolution
Darwin argued that living things have been evolving on Earth for millions of years. Evidence for this process include: 1.Fossils2.Comparative anatomy3.Biochemistry of different life forms
Fossil Evidence
Paleontology: Study of the fossil record.Fossils: Remains or traces of organisms that
lived in past ages, to understand past life forms.
Fossil Evidence
By comparing fossils from older rock layers with fossils from younger layers, scientists could document that life on Earth has changed over time.
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Fossil Evidence in sedimentary rock
Fossil Evidence
Some scientists have found transitional fossils.
Transitional fossils: Show a transition from one species to another.
For example: Whales
Transitional Fossils of Whales
• Older whales were hoofed mammals that lived on land.
• These animals were able to walk on land and swim.
• Later, fossils suggest that over time, the hind limbs of the whales’ ancestors shrank.
• Their forelimbs became flippers.
• Their hind limbs became a tail called a fluke.
Comparative Anatomy/Physical Features:
Homologous StructuresBody parts of different
organisms that have a similar structure but may have different functions.
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Comparative Anatomy: Homologous Structures
Composed of similar bones. Must mean they all shared anancestor that had a similar structure.
Comparative Anatomy: Analogous Structures
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Analogous StructuresBody parts that have a similar function but not a similar structure.They do not indicate shared ancestry.
Comparative Anatomy: Analogous Structures
Bird wing and butterfly wing
Comparative Anatomy: Vestigial Structures
Vestigial Structure:
A body part that does not seem to play a major role in an organism’s life functions but was more important in the organism’s ancestors.
Rats also have an appendix suggesting we share a common ancestor.
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Comparative Anatomy: Embryology
Embryology: Study of embryos.Embryo: Early stage of development in an organism.Embryos of related organisms develop in similar ways.
Copyright Pearson Prentice HallChick embryo (LM) Human embryo
Pharyngealpouches
Post-analtail
Biochemical Evidence of Evolution
Recall that all organisms contain the nucleic acid: DNA.
DNA directs the production of proteins which are made of amino acids.
The more similar an amino acid sequence is, the more closely related organisms are and most likely shared an ancestor.
We can compare hemoglobin: a protein found in RBC’s to determine this.
Biochemical Evidence
Biochemical Evidence
In addition to hemoglobin, Cytochrome C is another protein that determines how closely related species are to one another.
