Download Evolution

Theory of Evolution
•
Life on Earth, as well as the shape of Earth’s
surface, has a history of change that is called
evolution.
•
The evidence that organisms and landforms
change over time is scientifically described
using the following:
1. Theory of Plate Tectonics
2. Law of Superposition
3. Theory of Evolution
Theory of Evolution
• States that species change over time and
that living things change in response to
their environment.
• The change results from a change in the
genetic material of an organism and is
passed from one generation to the next.
Theory of Evolution
• Charles Darwin is
known as “The Father
of Evolution”
• His theory is the widely
held notion that all life is
related and has
descended from a
common ancestor.
Darwin’s Finches
• Darwin spent some time in the Navy and
traveled to many places.
• One of the places he traveled to was the
Galapagos Islands where he observed several
traits about the finches that lived there.
• He observed finches with heavy, short beaks
(good for pecking trees or seeds) and others
with small thin beaks (good for capturing
insects).
Darwin’s Finches
• These observations caused Darwin to
wonder whether if the birds had evolved
from similar species.
• He eventually developed a hypothesis that
accounted for the diversity he observed
called natural selection.
Natural Selection
•
In natural selection, members of a species that
are best suited to their environment survive
and reproduce at a higher rate than other
members of a species.
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Darwin based this idea on the following:
Overproduction
Variation
Adaptation
Selection
Overproduction
• When a species makes more than the
environment can handle so that a good
number have a chance of survival.
Variation
• Variation exists in the phenotypes (body
structures and characteristics-physical
traits) of the individuals within every
population.
• Phenotype can influence its ability to find,
obtain and use resources (food, shelter,
water) and might also affect its ability to
reproduce.
Adaptation
• Any inherited trait that gives an organism
an advantage in its particular environment.
• Ex. A slight change in the shape of a tail
fin might help a fish’s chance of survival by
helping it to swim faster and avoid
predators.
Selection
• Over time, more of the fish will have tails
that are shaped differently and will survive
to reproduce.
• As a result, they will make up a larger part
of the group.
Changes in Environmental
Conditions
• Changes in an environment can affect the
survival of individual organisms as well as
entire species.
• Organisms with characteristics that are
well suited to the new environment are
more likely to survive and reproduce at
higher rates.
Changes in Environmental
Conditions
• The alleles (genes) associated with
favorable phenotypes (physical traits)
increase in frequency and become more
common and increase the chances of
survival of the species.
• Those trails will be passed on to their
offspring.
Diversity and Survival
• Within a species, there is a variability of
phenotypic traits leading to diversity
among the organisms of the species.
• The greater the diversity, the greater the
chances are for that species to survive
during environmental changes.
Evidence Supporting Evolution
•
Evidence supporting evolution can be
observed by looking at the following:
1. Vestigial Organs (organs that were fully
developed and used by ancestors, but
are smaller and unused in current
species)
Evidence Supporting Evolution
• Similar Structures with Different Functions:
many species have similar organs, but
they have a different purpose in each
species (ex. Bone structure in lizards, bats
and manatees)
• This similarity indicates that they shared a
common ancestor at some point.
Biological Classification
• Biological classification is a system which
is used to organize and codify all life on
Earth (also called “taxonomy”)
• This allows scientists to examine
relationships between various organisms
as well as the relationship between current
and historical organisms.