EVOLUTION
Natural Selection
Review

Spontaneous Generation
Living
things

things come from nonliving
Vital Force
The
air contains something that
produces microorganisms
Review

When was the Earth formed?
 4.6

billion years ago
What were the first life forms?
 Prokaryotic

cells
Define Evolution.
 Describes
how things change over time
Thoughts in



th
18
Century
Scientists believed species were permanent and
unchanging
Earth was only thousands of years old
Scientists began to present evidence that species
change over time and that the Earth is much older.
Scientists are influenced by other
scientists

James Hutton: a geologist in 1785
 Realized
that certain kinds of rocks are formed from
molten lava
 Some other rocks form very slowly, as sediments build
up and are squeezed into layers
 Froces beneath Earth’s surface push rock layers upward
and build mountain ranges
 Mountains can be warn down by rain, wind, heat and
cold
Scientists are influenced by other scientists

Charles Lyell-1830-1833
 Laws
of nature are constant over time and that scientists
must explain past events in term of processes they can
observe in the present
Hutton and Lyell

Laws of nature concluded that Earth is extremely
old and that the processes that changed Earth in the
past are the same processes that operate in the
present
Jean-Baptiste Lamarck

French Naturalist
1.
2.
Suggested that organisms could change during their
lifetimes by selectively using or not using various parts
Suggested that individuals could pass these acquired
traits on to their offspring, causing change over time
Jean Baptiste Lamarck


1809
Inheritance of Acquired Characteristics
 Individuals
acquired traits during lifetime as a
result of experience then can pass those traits
onto their offspring.
 Larger
muscles from work, children would have
larger muscles
Thomas Malthus




English Economist
1798- notes humans were being born faster that
dying causing over crowding
Forces working against population growth, include
war, famine, and disease
Applied to other organisms as well
Alfred Russel Wallace


English naturalist working in Malaysia 1850’s
Thoughts were almost identical to Darwin’s which
caused Darwin to publish book
Charles Darwin


1809-1882
Traveled on the Beagle
 Noticed
similar organisms around the world
 Did a lot of work on Galapagos Islands off of
South America
 Wrote book On the Origin of Species by Means
of Natural Selection
 Used the phrase Descent with modification
 Beaks
of finches on Galapagos Islands
Natural Selection

Four main parts of Darwin’s reasoning
 Overproduction:
more offspring can be
produced than can survive to maturity
 Genetic Variation: individuals within a
population have different traits
 Struggle to Survive: individuals must compete
with each other for limited resources
 Differential Reproduction: individuals that
have certain traits are more likely to survive
and reproduce
Speciation


Speciation: the formation of new species
Convergent Evolution: different species evolve
similar traits because of environment they live
in


These species are not related
Divergent Evolution: organisms begin to look
different because of the environment they
live in

Adaptive Radiation: a new species in a new
environment will undergo divergent evolution until
population fills many part of the environment
Speciation

Geographic Isolation: a population is split due
to the habitat becoming divided


Ex: canyons, mountain ranges, bodies of water,
deserts, accidentally transported to new area
Reproductive Isolation: there are barriers to
successful breeding between population groups
in same area
Prezygotic: before fertilization
1.
1.
Ex. Mating calls, time of mating
Postzygotic: after fertilization
2.
1.
Ex: offspring cannot reproduce
Rates of Speciation


Gradualism: changes occur at a regular,
gradual rate
Punctuated Equilibrium: Many years of no
change, then all of the sudden have a
significant change
Evidence of Evolution


Fossil: remains or traces of an organism
from long ago.
Biogeography: study of the location of
organisms
1.
2.
Animals that seemed closely related yet are
adapted to different environments in nearby
regions.
Animals that seemed unrelated but have
similar adaptations to similar environments
Evidence of Evolution

Anatomy and Embryology
 Anatomy:
the study of body structure
 Embryology: the study of how organisms
develop
 Homologous
Structures: anatomical structures
that occur in different species and that
originates by common ancestor
 Ex:
human, penguin, alligator, bat all have a
humerus, radius, and ulna
Evidence of Evolution

Analogous Structure: structures that have similar
functions but different structures


Vestigial Structure: structure that have no known
function


Ex: wings of birds and insects
Ex: tailbone, appendix
Biological Molecule

DNA and RNA

The greater number of similarities between any given
species the more closely related