Transcript ppt

Darwin’s Theory of
The History of Evolution
• Evolution is defined as change over time
• The theory that all organisms on Earth are
related by common ancestry and that they
have changed over time (adapted) mostly
because of natural selection.
• Charles Darwin is one of the most famous
scientists associated with the theory of
Darwin’s voyage
Darwin’s interest
• Darwin’s observations and research played
an important role in the development of the
theory of evolution that is still widely
accepted today
• During his voyage on the U.S.S. Beagle, he
would collect specimens from the different
areas he visited
• He was fascinated to see the variety in the
different plants and animals that he studied
He did notice one
All of the organisms he observed
were well suited (well matched) to
their environment
Beaks of finches
• The finches beaks have adapted and naturally
selected for over time based on what they eat
• An adaptation is any inherited characteristic
that increases an organisms chance for
• Adaptations can be physical or behavioral and
can be passed from generation to generation
• The process of becoming better suited to the
Different types of adaptations:
• Genetic adaptation – always genetically
controlled (ex: 5 fingers, giraffe’s neck)
Different types of adaptations:
• Physiological adaptation – change in the
reactions; can be genetic or not (ex:
acclimation to altitude or climate, coat
color change during seasons)
Different types of adaptations:
• Behavioral adaptation – change in
behavior; can be genetic or not (ex:
chimps using sticks to catch termites,
bears eating garbage)
Survival of the fittest
• The ability of an individual to survive and
reproduce is called fitness
• Adaptations that help an animal become
more fit to survive and reproduce more
successfully are commonly selected
• This is known as survival of the fittest
Survival of the fittest is
also known as natural
Over time, natural selection
will change the
characteristics of a
increasing the fitness of
that population
Proof? You want proof?
• Evidence of evolution through adaptation
and natural selection can be found in:
– the fossil record
– Geographical distribution (different animals evolve
similarly because of the same environmental factors)
– Homologous structures
– Similarities in early development of embryos
Fossil Record
Geographical Distribution
Geographical Distribution
Homologous structures
Homologous structures
Development of embryos
Development of embryos
• Evolution is widely accepted by the scientific
• Theories are constantly changing based on new
evidence (mitochondrial DNA/rapid evolution…)
• Evolution is still occurring
• Many species are becoming extinct because they
cannot evolve as fast as humans are changing
the environment.
• Humans are “meddling” with evolution through
artificial selection (fruit, dogs…)