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EVOLUTION

What is “Evolution”?


gradual change in inherited characteristics by certain
biological populations over successive generations



processes that has transformed living creatures on
Earth from its earliest form to the vast diversity
it is today

What are pieces of evidence that support evolution?
1) Fossil Records
2) Anatomical Structures
- Homologous and Analogous Structures
- Embryonic Similarities
- Vestigial Structures
3) Biochemical Evidence
4) Artificial Selection

1) FOSSIL


any preserved part or tissue of an organism that
once lived



are formed when substances in the soil replace
the soft, easily decomposed part of the dead organisms body

Types of Fossils
 Petrified fossils


formed when minerals in mud and sand replace hard parts of an organism

 Imprints


formed when soft, thin body structures such as feathers
and leaves make impressions on soft sediments such
as mud

 Molds and Casts


formed when an organism is buried by sediment
that later harden into rock

"molds"
- made as empty spaces in the rock are formed because
the organism has decayed over-time
...


 Tar Pits
 formed when animals are trapped in sticky tar when they
drink the water that often covers the pit

 Freezing
 preserves organisms in ice

4) ANATOMICAL STRUCTURES

 Homologous Structures
 body parts that are similar in structure, but have different functions

 Analogous Structures
 body parts that have similar functions, but have different
anatomical structures

 Vestigial Structure
 structures that are reduced in size and appear
to have no function

 Embryonic Development
 Appears among different organisms suggesting that
they may have evolved from the same ancestors

3) BIOCHEMICAL EVIDENCE
 The greater similarity in the protein structure of
organisms, the closer the relationship between them

4) ARTIFICIAL SELECTION
 process by which humans breed other animals and plants for particular traits
 "evolution by human selection"

Theories
Lamarck’s Theory




"acquired traits can be inherited" : proposed
that organisms change as their environment changes
and acquired traits are passed off to offspring
"use and disuse": proposed that structures that
are not often used become smaller in size and those
that are often used are developed

Darwin’s Theory


the environment selects organisms with beneficial traits
or adaption (Natural Selection)



if favored trait is successfully passed in and becomes
present in all individuals of next generation, these traits
will be called adaptations and they were developed through
natural selection



an organism is "fit" or best suited for the environment
should be able to survive and reproduce passing on its traits
to its offspring

The Theory of Evolution


Variations are individual differences among member of a
particular species



They are inheritable because these are due to the presence
of alleles

Patterns of Evolution

1) Convergent Evolution


a process by which distantly-related organisms develop
similar characteristics

2) Divergent Evolution


a process by which related organisms become different
- results to speciation (formation of a new species)



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