Notes and summary on Evolution studies - IEB Matric bio/life Science
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Course
Life Sciences
Institution
12th Grade
Notes and summary on Evolution studies. Covers strictly what you need to know for all tests and assessments (as dictated by the SAGS guidelines). Includes annotated diagrams and images to illustrate points mentioned, as well as additional research, helpful when understanding the work (I achieved a ...
BIOLOGICAL EVOLUTION
DIVERGING into one or more different species, or the formation of brand new SPECIES
describes how organisms change and adapt over time as a result of
THEORY OF
inherited physical + behavioural characteristics that are passed down to
EVOLUTION
offspring "descent with modification."
MACRO EVOLUTION MICRO EVOLUTION
evolutionary change on a large scale that
evolutionary change on a small scale, such
happens over a longer period of time
as changes due to mutations occurring on a
diverging into one or more different
single gene or a few genes in a single
species, or the formation of brand new
population over a short period of time.
organisms
MIRCO evolution → MACRO evolution
Results in a new speices
Over time
4 MECHANISMS OF EVOLUTION
NATURAL SELECTION MUTATION GENETIC DRIFT GENE FLOW
process in nature by
which organisms Mutations are
Genetic drift is a migration of genes
better adapted to caused by changes in
random change in between individuals
their environment the base sequences
allele frequencies due to reproduction
tend to survive and in the DNA
reproduce
ADAPTATION
A trait that improves an organism's ability to survive and reproduce in an environment
COMMON ANCESTOR VARIATION FITTEST
Difference between traits in
An ancestor shared by two The ability of an organism
individuals of the same
or more descendant species to survive and reproduce
species
Darwin's theory of evolution states that evolution happens by
natural selection. Individuals in a species show variation in physical
DARWINS THEORY
characteristics as a consequence those individuals most suited to
OF EVOLUTION
their environment survive and, given enough time, the species will
gradually evolve.
DARWIN PROPOSED THAT
individuals with the characteristics that
individual organisms within a
characteristics most suited have enabled these
particular species show a
to the environment are individuals to survive are
wide range of variation for a
more likely to survive to then passed on to the next
characteristic
breed successfully generation
THIS THEORY IS CALLED NATURAL SELECTION
EVOLUTION BY NATURAL SELECTION PRINCIPALS
VARITATION OVERPRODUCTION SURVIVIAL OF THE FITTEST
, There are variations Those individuals whose traits
Populations tend to
amongst the individuals of best allow them to adapt to the
produce more offspring
most populations environment will survive better
than the environment
INHERETANCE and leave more offspring than
can support
Variation can be inherited those with less adaptive traits
Life forms evolved from previous life forms by the process of NATURAL SELECTION. Most
species are unable to survive in a new environment, and become extinct, but a few species
may become successfully adapted to a new environment. These SUCCESSFUL
ADAPTATIONS are due to BENEFICIAL MUTATIONS and happen completely RANDOMLY!
Organisms do not choose to mutate.
NATURAL SELECTION
is a process where
This means that the Over many generations,
organisms that are better
advantageous alleles of this the process of natural
adapted to an
variant organism are passed on to selection leads to
environment will survive
offspring. evolution occurring.
and reproduce.
Individuals have If this continues over generations, The population evolve
variations within their these favourable adaptations (change in its genetic
heritable traits make an (that aid survival and makeup) in such a way
individual better suited to reproduction) will become more that it becomes adapted,
survive and reproduce in and more common in the or better-suited, to its
their environment. population. environment.
MUTATIONS INCREASED ALLEL FREQENCY MICRO EVOLUTION
ARTIFICAL SELECTION where humans select for desirable traits in agricultural
products or animals to produce desirable or fashionable traits
selective breeding
PHENOTYPE.
, NATURAL SELECTION leaving the species to evolve and change gradually without
Random breeding human interference
Natural selection acts on
Natural selection depends on Heritable variation comes
existing heritable
the environment from random mutations
variation
Natural selection doesn't favour Natural selection needs new gene variants produce
traits that are somehow some starting material, new heritable traits, is
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