Download Evidence of Evolution

The Theory of Evolution
Evolution
• a gradual change in the genetic material of a
population.
• (Population = all the animals of the same
species living within a region)
Darwin and the Voyage of the Beagle
Charles Darwin- the scientists given credit for the discovery
of evolution through natural selection.
Darwin’s Observations
• Patterns of Diversity
Darwin’s Observations
• Living Organisms and Fossils
Darwin’s Observations
• The Galapagos Islands
An Ancient,
Changing Earth
• Previous scientists recognized that Earth is many
millions of years old, and the processes that
changed Earth in the past are the same processes
that operate in the present.
The Earth has changed and is still
changing…
Natural Variation
Individuals, even of
the same species,
always contain
some differences or
variation.
Additional variation
can be added
through genetic
mutations.
Evolution by Natural Selection
Organisms best suited for their surroundings
will survive and pass on their genes to the next
generations. Overtime, only the best genes
will remain.
The Evolution of the Peppered Moth
In England a species of moth called the Peppered Moth had two
available, inheritable wing colors- a light color and a dark color.
(Dark colored moths had dark colored babies, and vice versa.) Prior
to the industrial revolution, the light color dominated with 99% of
the moths displaying this phenotype, because it helped the insect
blend in light colored lichens covering the trees. However, after the
factories opened, the light phenotype became almost extinct and
the darker color began to dominate. Why do you think this
happened?
Evidence of Evolution
Darwin argued that living things have been
evolving on Earth for millions of years.
Evidence for this process could be found in the
fossil record, the geographical distribution of
living species, homologous structures of living
organisms, and similarities in early
development.
Evidence of Evolution
The Fossil Record
Evidence
of Evolution
Geographic
Distribution
of Living
Species
Evidence of Evolution
Homologous Body Structures
Vestigial Structures
Evidence of Evolution
Similarities in Early Development
Patterns of Evolution
• macroevolution: large-scale evolutionary
changes (ex: Reptiles evolving into birds)
• Microevolution: small evolutionary changes
(ex: the peppered moth)
• Punctuated Equilibrium: Evolution is not a
slow process. It consists of long, stable periods
interrupted by rapid and brief periods of
change.
Divergent Evolution
• divergent evolution: two related species
develop more and more differences
– examples:
polar bear – white fur for camouflage
grizzly bear – brown fur to fit in environment
• If the populations are isolated, it leads to
speciation – the formation of new species.