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The History of Life on Earth

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The History of Life on Earth A 4.6 BILLON YEAR STORY – PowerPoint PPT presentation

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Title: The History of Life on Earth


1
The History of Life on Earth
  • A 4.6 BILLON YEAR STORY

2
  • Relative dating and The Law of Superpostion
    oldest materials are buried below younger
    materials.
  • Radiometric dating- Uses the amount of time it
    takes for half of the radioactive carbon, C14, to
    leave a sample. Can also use other atoms such as
    uranium or polonium Gives an exact age (AKA
    Knowing the half-life.)

3
  • Era- divisions of geologic time
  • Precambrian- life startsbacteria
  • Paleozoic- first fish, land plants, amphibians,
    reptiles...
  • Mesozoic- first dinosaurs, mammals, flowering
    plants, birds
  • Cenozoic- Mammals dominate, humans evolve

4
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5
  • Evolution- the scientific theory that explains
    how early life on earth changed into the
    diversity of life in present time.
  • Definition Change in allele Frequency of a
    Population Over Time

6
  • Hypothesis- a suggested solution to a problem
  • Theory- an explanation of a set of related
    observations verified multiple times.
  • Law- a statement of fact meant to explain.

7
  • Jean Baptiste Lemarck- Wrote in 1809, after
    studying the fossil records, that the Earth is
    ancient.
  • Evolution driven by tendency toward increasing
    complexity
  • Proposed 3 mechanisms of evolution
  • Use and disuse
  • Inheritance of acquired characteristics
  • The want to change

8
  • Charles Darwin- A naturalist that signed on the
    HMS Beagle in 1831 to collect flora and fauna

9
  • HMS Beagle- A ship that voyaged to chart South
    American coastline
  • Darwin found
  • Flora fauna distinctly different from that of
    Europe
  • Climate not a key factor
  • Fossils resembled living species

10
  • Galapagos Islands- Group of volcanic island near
    the equator, 900 km west of South America
  • Most animals unique to islands, but resemble
    those from the mainland

11
  • The Origin of Species- Published in 1859 and
    first introduced the idea of evolution by natural
    selection
  • Descent with modification- Organisms related
    through descent from an ancestral population
  • Natural selection and adaptation- Some
    characteristics assure better chance of survival
    and successful reproduction

12
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14
  • Natural Selection- the unequal ability of
    individuals within a population to survive and
    reproduce
  • Survival of the fittest- a quick way of
    describing natural selection.

15
Occurs through interaction between genetic
variability of individuals of population and
their environment
  • Environmental Conditions- The state of an
    organisms surrounding at a particular time.
  • Differential Survival- Some organisms are lucky
    and end up with traits and adaptation that
    exceed other organisms.

16
  • Niche- all of the interactions of a species with
    the other members of its community. The job of
    a species.

17
  • Fossil record- can be used as evidence of a
    transitional life over time.

18
  • Comparative anatomy- the study of the body
    structures of different species of animals

Analogous structures- features of different
species that are similar in function but not
necessarily in structure.
Homologous Body Structures- Body parts in
different organisms that are similar, but do not
necessarily serve the same function
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20
Vestigial structures- Body structures that have
no apparent function
Embryonic stages- Comparing different animals
fetal developments to infer relationships between
species
21
  • Chemical basis- organisms sharing similarity at a
    molecular level.
  • DNA- nucleotide sequences
  • Protein sequences- amino acid sequences
  • Cladogram- used to show ancestral relations
    between organisms

22
  • Speciation- The evolutionary formation of new
    biological species, usually by the division of a
    single species into two or more genetically.

Reproductive Isolation- occurs when members of
two populations cannot interbreed. At that
point, they have different gene pools.
Behavioral Isolation Two populations capable of
interbreeding but have differences in courtship
rituals or other types of behavior.
Geographic Isolation Populations are separated
by geographic barriers such as rivers, mountains,
or bodies of water.
23
  • Types of selection
  • Directional Selection Evolution causes an
    increase in the number of individuals with the
    trait at one end of the curve.

Stabilizing selection - Individuals in the center
of the curve and more fit and thus the curve
narrows
Disruptive Selection- Individuals at the ends of
the curve are more fit than the ones in the
middle causing two curves to form and possible
new species to form.
24
  • 4 Mechanisms of evolution
  • Mutation- A change in an individuals genes.
  • Migration- individuals moving from a population
    to another population.

Natural selection- Genetic changes from
generation to generation by unequal ability to
survive to reproduce.
Genetic Drift- Genetic changes by chance.
25
  • Variation- any difference between individual
    organisms in a population.
  • Adaption- process whereby a population becomes
    better suited to its habitat.

26
  • Artificial selection- certain characteristics
    being selected for many years leading to breeds

www.puppy-training-solutions.com/image-files/dog-b
reed-information.jpg
27
Mechanism (8) Macroevolution
  • However, if two populations of a
  • species become isolated from
  • one another for tens of thousands
  • of years, genetic difference may
  • become marked.
  • If the two populations can no-longer
  • interbreed, new species are born.
  • This is called Macroevolution.
  • Darwins Galapagos finches are
  • an example of this process in action.

Galapagos finches
www.ingala.gov.ec/galapagosislands/images/stories/
ingala_images/galapagos_take_a_tour/small_pics/gal
apagos_map_2.jpg
28
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