Download Evolution Notes

Evolution Notes
Part 1
Charles Darwin

Born in England
 Traveled around on
HMS Beagle - Set
Sail in 1831
 Collected many
specimens
 Father of the idea of
Evolution
Voyage of The Beagle
Darwin & The Galapagos
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Galapagos Islands are
a small group of islands
1000km west of South
America
Studied Tortoises and
Finches on the islands.
Used geography of
islands and
differentiation of
species to figure out
evolution
Galapagos Islands
Galapagos Islands

Although they were close together, the
islands had very different climates.
 The smallest, lowest islands were hot, dry,
and nearly barren.

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The higher islands had greater rainfall and a
different assortment of plants and animals.


Hood Island - sparse vegetation.
Isabela Island - rich vegetation
Allowed for different species of the same
animal --> formed through evolution!
Galapagos Finches
Galapagos Finches
Galapagos Tortoises
Galapagos Blue-Footed Booby
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Male dances and shows
its feet to the female to
attract her
Female chooses male
with brightest feet and
best dance
Sexual selection!
Sexual selection is a
trait or behavior that
acts on an organism's
ability to obtain a mate
Darwin’s Thoughts

On his travel home, he began to think of his
observations.
 He found…characteristics of many animals
and plants varied noticeably among the
different islands of the Galapagos
 According to this hypothesis, these separate
species would have evolved from an original
South American ancestor species after
becoming isolated from one another
Inherited Variation and Natural
Selection

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Darwin noted that plant
and animal breeders
used heritable variation,
what we now call genetic
variation, to improve
crops and livestock.
Artificial selection:
nature provided the
variation, and humans
selected those variations
that they found useful.

A.K.A Selective Breeding
Better Picture of Artificial
Selection
Natural Selection

Each organism has different
advantages and disadvantages
 Individual
best suited for environment
survive and REPRODUCE
 Pass these traits onto offspring, and they
are more able to survive and reproduce
Occurs only when a few survive
 Remember: differences (genes) in
offspring occur at random!

Darwin’s Concept of Evolution

Biggest contribution is his idea of the
mechanism behind Evolution
 The
Struggle for Existence
 Survival of the Fittest
 Descent with Modification
Struggle For Existence

Struggle for existence: means that members
of each species compete regularly to obtain
food, living space, and other necessities of life.
 Predators that are faster win
 Prey that are better camouflaged or
protected win
Survival of the Fittest

Fitness: ability of an
individual to survive and
reproduce in its specific
environment.
 Result of adaptations
 Adaptation: any
inherited characteristic
that increases an
organisms chance of
survival
Survival of the Fittest

Survival of the
Fittest: the idea that
individuals that are
better suited to their
environment survive
and reproduce more
successfully
 A.K.A. Natural
selection
Descent with Modification

Natural selection
produces organisms
that have different
structures
 Descent with
modification: each
living species has
descended, with
changes, from other
species over time