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Summary Life Science EVOLUTION NOTES
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Covers all you need to know about evolution for the final matric paper (NOT HUMAN EVOLUTION) With diagrams and mind maps.
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GRADE 12EVOLUTiON
G
, Evolution By Natural Selection Driven by change in the environment Evolution is a scientific theory
bcz it's based on series of
EVOLUTION: change over time hypotheses that have been
BIOLOGICAL EVOLUTION: genetic changes in a population that are inherited tested and verified over time
over successive generations due to natural selection which leads to a new species.
↳ MACRO : development of new life forms or species from earlier life forms from many generations.
↳ MICRO: variation that occurs within a species, small changes occur in the gene pool = small changes in the genotype of the species which are
passed on to offspring.
development of the theory of evolution
1. 7 Rich biodiversity
THREE MAJOR OBSERVATIONS WHEN 2. 7 Organisms adapt to particular environments
STUDYING NATURAL ENVIRONMENT 3. ↓ Continuous changes take place
ERASMUS DARWIN
⦾ Life on Earth originated from a single ancestor
⦾ Similarities between different organisms = one species developed from another
⦾ Artificial Selection and metamorphosis
JEAN BAPTISTE de LAMARCK
1. Law of Use and Disuse : The use of disuse of organs may cause
organs to increase or decrease in size or even disappear
.
2 1. Law of Inheritance of acquired characteristics: Changes in
characteristics that occur in an organisms life will be inherited by
their offspring = changes in population and forms new species
REJECTION OF LAMARCKISM
⦾ Lamarck was the first scientist to propose that the characteristics of a parent would be passed onto the offspring
⦾ No understanding of genes and mutations
⦾ The ancestors of the giraffe possessed the gene for long strong necks and did not acquire the genes for stretching their necks
CHARLES DARWIN
1. Individuals of a population produce more offspring than required
2. A great deal of variation occurs in a population
3. Some individuals are better adapted to an environment and are more likely to produce than the weaker ones OBSERVATIONS
4. Characteristics are transferred from surviving parent to offspring
THEORY OF EVOLUTION BY NATURAL SELECTION
1) Organisms produce a large number of offspring
2) There is variation in the offspring
3) Some individuals have favorable characteristics ( advantages in the environment)
4) When there is a change in environment, the individuals with favorable characteristics will survive
5) Organisms with non-favorable characteristics are less fit = population will decrease
6) The organisms that survive will reproduce ∴ pass on favorable characteristic
7) Next gen has more individuals with favorable characteristics
8) The changes within individuals of a species may lead to the formation of new species ( SPECIATION)
BOTH DARWIN AND LAMARCK BELIEVED Punctuated Equilibrium
⦾ Initially life was simple but overtime became complex as environment changed
⦾ Species constantly change, new species are formed , some extinct ⦾ Gradualism- a slow gradual change in a species
⦾ Only those best adapted to environment will survive
⦾ Species in Equilibrium until quick sudden changes interrupted
⦾ Either individuals failed to adapt OR experienced favorable
mutations so they could adapt
⦾ Punctuated equilibrium- explains how changes leading to
speciation may occur very rapidly and it accounts for the
absence of traditional fossils
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