The History of Life on Earth

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The History of Life on Earth

• A 4.6 BILLON YEAR STORY

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• 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.)

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• 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

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• 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

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• 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.

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• 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

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

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• 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

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• 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

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• 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

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• 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.

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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.

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

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

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• 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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Vestigial structures- Body structures that have
no apparent function
Embryonic stages- Comparing different animals
fetal developments to infer relationships between
species
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• 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

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• 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.
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• 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.
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• 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.
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• Variation- any difference between individual
  organisms in a population.
• Adaption- process whereby a population becomes
  better suited to its habitat.

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

www.puppy-training-solutions.com/image-files/dog-b
reed-information.jpg
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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
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