Transcript The Evolution of Living Things Chapter 8.1 Change Over Time

The Evolution of Living Things
Chapter 8.1 Change Over Time
Differences among organisms
• Adaptation
• Can include
• Species
• Requirements
• Example
a hereditary characteristic that helps
an organism to survive and reproduce
in its environment
structures for behavior, finding food,
protection, moving from place to place
living things that share the same
characteristics and adaptations
can mate with one another to produce
fertile offspring
Red-eyed tree frog
Change over time
• Species today
• Earth age
• Fossil evidence
• Process of evolution
range from bacteria
that lack cell nuclei to
multi-cellular fungi
(plants and animals)
4.6 billion years old
shows that living
things have changed
over time
newer species have
descended from older
species
Evolution
• The theory that populations accumulate changes over time
• Because of evolution scientist believe that all living things from daisies to
crocodiles to humans share a common ancestor
Evidence of evolution
• Fossil record
• Fossils formed
»
Trilobite an ancient
aquatic animal
related to the crab
solidified remains or imprints of once
living organisms
usually a dead organism is covered by
a layer of sediment
*minerals in the sediment may seep
into the organism, gradually replacing
the organism with stone
*organism may not rot completely and
form a hole in the rock called mold
sedimentary layers
Seed fern leaf,
300 million years old
Reading the fossil record
• Fossil record
a historical sequence of life
shows the order in which evolutionary changes
have occurred
shows how environmental conditions on earth
may have changed
• Time sequencing
the deeper in the earth’s crust the less they
look like present day organisms
the upper layers of the earths crust tend to
resemble present day creatures
Gaps in the fossil record
• For a fossil to form
specific conditions must be present
*skeleton must be buried in sediment
that is very fine
*oxygen O2 must not be present (it
promotes decay)
» Conditions to create fossils are very rare, and sometimes
fossils are difficult to find
Vestigial structures
• Vestigial structure
• Example
See page pg. 180181
remnant of a once useful structure
appendix
Evidence of evolution
• Evidence of evolution
comparison of different
organisms
• Skeletal structures
similarities indicate that animals are all
related by a common ancestor
»Evolutionary process modified these bones over millions
of years to perform specialized functions
• DNA
all have the same genetic DNA- no other
genetic molecule has been found
»The more closely related the more similar the DNA is
• Embryonic Structures
vertebrate embryos look very
similar
»Changes in the process of embryo development produce
different animals
Skeletal Structures
• .
Human arm
Cat leg
Dolphin flipper
Bat wing
The most similar bones are shown in the same color
DNA from different species
• .
Embryonic structures
• .
The Evolution of Living Things
Chapter 8.2 How does evolution happen?
How does evolution happen
• 1800s
scientists realized earth is older than anyone
had previously thought
• Evidence shows
gradual processes had shaped the Earth’s
surface over millions of years
Charles Darwin
• 1831
graduated from college with degree in thoelogy
father wanted him to be a doctor but Darwin was
interested in natural science
HMS Beagle
Darwin took a 5 year voyage around the world serving
as a naturalist
Observations
Darwin made observations on this voyage that later
became the foundation for the theory of evolution by
natural science
Darwin’s adventure
• Collections
thousands of plant and animal samples
took detailed notes
• Galapagos islands
observed that animals and plants were similar
but not identical to plants and animals in
nearby South America
• Finches
different than finches in South America
(Ecuador) and from each other (mainly the
shape of their beak, and the food they ate)
• Theory
finches that survived may have adapted to
various ways of living on the Galapagos
Islands
•
Darwin learned from farmers and
animal and plant breeders
• Selective breeding
humans choose the trait they want passed
along to the next generation
• Farmers
chose certain traits for farm animals
• Breeders
chose traits that shaped the breeds we see
today
Darwin learned from geologists
• Charles Lyell
wrote “Principles of Geology” which said the
Earth had been formed by natural processes
over a long period of time
• Thomas Malthus
wrote “Essay on the Principle of Population”
which states that human populations have the
potential to reproduce uncontrollably, beyond
the available food source
» Darwin noted that since some of these species without
enough food survived then there must be something
special about them, which helps them to survive
Natural Selection
• 1858
20 years after his voyage on the HMS Beagle Darwin
received a letter from Alfred Russel Wallace
had
independently come up with the same theory of
evolution that
Darwin had been working on
• Published
“On the Origins of Species by Natural Selection”
• Theory
evolution occurs through a process called natural
selection
Natural Selection
More evidence of evolution
• Evolution by natural selection
parents pass traits to their
offspring
• 1930-40
biologists combined principles
of genetic inheritance and
theory of evolution by natural
selection
Darwin’s
• Mutations
responsible for the changes
Darwin saw (changes at the DNA
level)
The Evolution of Living Things
Chapter 8.3 Natural Selection in Action
Natural selection in action
• The Theory of Natural Selection
how populations change over
many generations to adapt to
changes in the environment
Insecticide Resistance
• Resistance to insecticides
over 500 species of insects have
developed a resistance to
certain insecticides
• Quick adaptation
they evolve quickly to resist certain
poisons quickly because they have
short generation times
• Generation time
the period between the birth of one
generation to the birth of another
generation
• Antibiotic resistant disease
tuberculosis and other diseases are
becoming resistant to antibiotics
because the surviving microorganisms
are becoming strong antibioticresistant strains
Adaptation to pollution
• Example European peppered moth
Originally dark moths were easier for birds to see and eat, after the influence of
pollution turned nearby tree trunks darker the lighter moths were easier to see and
eat for the birds
More dark moths survived and produced offspring that were dark, so the
population shifted.
Formation of a new species
• Process of natural selection
explains how a species can evolve into
a new species
• 1-Separation
a portion of the population is cut off from the
rest of the population
• 2-Adaptation
separated groups may adapt to fit their
environment
• 3-Division
oven hundreds, thousands, or even millions of
years the two groups may become so different
that they can’t interbreed
– When species can’t interbreed they are no longer considered
to be the same species