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Chris Maltby

on 9 June 2014

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Transcript of Evolution

Earth's History
4 billion years old.
Solar nebula -- We are all made of stars.
Organic compounds
came first.
developed second.
Living examples today: Archaebacteria -- extreme-o-philes.
The First
(developed after prokaryotes)
Arose from
- a mutually beneficial relationship inside cells.
Prokaryotes served the function of organelles.
Eventually these prokaryotes evolved into true organelles.
Heavy Hitters of Evolution
Jean Baptiste Lamarck (1774-1829)
Theorized that
aquired traits
were passed on to offspring.
Proposed similar living species were descended from extinct species in the fossil record.
Aquired Traits -
Not based on genes. These traits were aquired via experience and behavior.
Sailed on the H.M.S. Beagle (world wide).
Collected fossils and observed thousands of species of organisms
Collected 13 finches on the Galapagos Island.
Charles Darwin (1809-1882)
Darwin's Theories from ORIGIN OF SPECIES (1858).
Descent with Modification -
The new organisms in the fossil record are modified descendents of older species.
Darwin took Lamarck's theory further.

- A single organisms genetic contribution to the next generation.
Modification by Natural Selection -
Organisms with favorable traits reproduce more. The environment selects what traits are favorable.

- A population is said to adapt when a favorable trait is passed on to offspring -- increase the frequency of the trait.
Adaptive Advantage
- The benefit a favorable trait gives an organism.
Natural Selection
- Organisms best suited for their environment reproduce more successfully than other organisms.
Evidence of Evolution
Homologous Structures -
Similar features that originated from a shared anscestor.
Here the same bones are
Homologous Structures.
Homologous Structures

point to a common ancestor.
Analogous Structures -
show organisms are not related.
Similar features that perform similar functions
Different internal anatomy
Different embryological development.
E.G. moth and humming bird wings.
Vestigial Structures -
Useless features that were used by an anscestor.
Vestigial tail bones in humans
= tails
Vestigial appendix
= added digestion for a rough diet.
Vestigial pelvis

four chambered stomach
of whales = simliar to a land mammal (cow).
Spurs in snakes
= limbs.
Similarities in Embryology
These similarities fade as the organism developes.
Early embryo development of all vertebrates is very similar.
Used to support Darwin's theories.
DNA (chimp/human 99% similar).
Hemoglobin (gorilla/human one amino acid different).
The number of amino acids is the same proteins in two species is proportional to the time since the two shared a common ancestor.
Similarities in macromolecules
Patterns of Evolution
- Evolutionary change in species with a close association with each other.
Many predator-prey relationships
Many parasites and hosts
E.G. Bats and Flowers
E.G. Birds and Flowers
E.G. Insects and Flowers
What else?
Convergent Evolution
- When species seem similar but are not closely related at all.

Occurs when the environment selects similar phenotypes with very different genotypes.
E.G. Porpoise and Sharks.
Adaptive Radiation
- When many related species evolve from a single ancestor. Examples?

Artificial Selection
- Divergent evolution sped up by selective breeding.

Divergent Evolution
- When two or more related populations become more and more dissimilar.
Usually a result of different habitats.
Can lead to new species
E.G. Darwin's Finches
Full transcript