Transcript Chapter 7 Changes Over Time A Branching Tree

Chapter 7 Changes Over Time
Section 1:
Darwin’s Theory
What important observations did Darwin make on his
voyage?
How did Darwin account for the diversity of species
and the differences between similar species?
How does natural selection lead to evolution?
Chapter 7 Changes Over Time
Darwin’s Voyage
Charles Darwin sailed on the HMS Beagle, from England to
the Galápagos Islands and back, for 5 years starting in 1831.
Chapter 7 Changes Over Time
Galápagos Islands
Located 525 miles
west of Ecuador.
Was visited by
Darwin in 1835.
Chapter 7 Changes Over Time
Galápagos Finches
Darwin noticed that
on each island, the
finches had adapted
to the local
environment.
Adaptation: a trait
that helps an
organism survive and
reproduce in its
environment
Chapter 7 Changes Over Time
Galápagos Finches
Chapter 7 Changes Over Time
Overproduction and Variation
Natural selection is the process by which individuals who are
better adapted to their environment are more likely to survive
and reproduce than other members of the same species.
Chapter 7 Changes Over Time
Competition and Selection
Variations among turtles make some of them better able to
survive. Turtles that survive to become adults will be able to
reproduce.
Chapter 7 Changes Over Time
Competition and Selection
Variations among turtles make some of them better able to
survive. Turtles that survive to become adults will be able to
reproduce.
Chapter 7 Changes Over Time
Factors that Affect Natural Selection
Overproduction
Animals (including humans), plants, and other
organisms tend to produce too many offspring,
and there may not be enough food, water, or
shelter to protect them all.
Chapter 7 Changes Over Time
Factors that Affect Natural Selection
Variation
Members of the same species differ from one
another in many of their traits
Example: You may be faster than your sibling,
but your sibling may be taller, or have a better
immune system, or have better reflexes.
Chapter 7 Changes Over Time
Factors that Affect Natural Selection
Competition
All living things struggle to survive. Sometimes
they compete for more food, or running away
from a predator, or fighting off a disease.
Chapter 7 Changes Over Time
Factors that Affect Natural Selection
Overproduction + Variation + Competition =
Natural Selection
The environment “selects” which members of a
species lives long enough to have offspring. Some
members have lots of offspring, others have few, and
some have no offspring.
Over time, helpful traits (like speed, camouflage, and
disease-resistance) will show up more often in a
species. Eventually, most members will have this trait.
Chapter 7 Changes Over Time
Things to Remember
• Species: a group of similar organisms
that can mate with each other and produce
offspring
• Overproduction: species creating more
offspring than can possibly survive
• Adaptation: a trait that can help an
organism survive
Chapter 7 Changes Over Time
Section 2:
Evidence of Evolution
What evidence supports the theory of evolution?
How do fossils form?
What do scientists learn from fossils?
Chapter 7 Changes Over Time
Homologous Structures
The structure of the bones in a dolphin’s flipper, a bird’s
wing, and a dog’s leg is similar. Homologous bones are
shown in the same color.
Chapter 7 Changes Over Time
Similarities in Early Development
Chapter 7 Changes Over Time
Similarities in DNA and Protein
Chapter 7 Changes Over Time
How Do Fossils Form?
Most fossils form when organisms that die become buried in
sediments.
Chapter 7 Changes Over Time
Types of Fossils
Molds and Casts: Most common fossil; organism dies and
gets buried in sediment, creating a mold; more sediment
later fills in this mold to create a cast
Chapter 7 Changes Over Time
Types of Fossils
Petrified: rock minerals replace parts of the organism, turning
the fossil into a hard, rock-like state
Chapter 7 Changes Over Time
Types of Fossils
Trace: evidence of activity, such as footprints or cave
paintings
Chapter 7 Changes Over Time
Types of Fossils
Preserved Remains: organism trapped in amber, tar or ice;
produces the best fossils
Chapter 7 Changes Over Time
Section 3:
Evolution of Species
What factors have contributed to the diversity of
species?
How do new species form?
How do scientists infer evolutionary relationships
among species?
What causes the extinction of species?
Chapter 7 Changes Over Time
Evolution in Progress
There are over 150
major breeds of
dogs and hundreds
of other crossbreeds. All of these
dog breeds (and
wolves) came from
the same ancestral
animal
Chapter 7 Changes Over Time
Kaibab and Abert’s Squirrels
These two kinds of squirrels have
been isolated from one another
for a long time. Eventually this
isolation may result in two
different species.
Kaibab Squirrel
Abert’s Squirrel
Chapter 7 Changes Over Time
A Branching Tree
This branching tree shows how scientists now think that
raccoons, lesser pandas, giant pandas, and bears are
related.
Chapter 7 Changes Over Time
Extinction of Species
Extinction is caused by a change in species'
environment. The members of a species may
not have adaptations that allow them to survive
and reproduce in the changed environment.
Baiji River Dolphin
Thylacine
Woolly
Mammoth
Chapter 7 Changes Over Time
Things to Remember
• Extinct: no more members of a particular
species exist; occurs when a species does
not have the right adaptations to survive
and reproduce
Chapter 7 Changes Over Time
End of Section:
Evolution of Species
Chapter 7 Changes Over Time
Section 4:
Classifying Organisms
Why do biologists organize living things into groups?
What do the levels of classification indicate about the
relationship between organisms?
What characteristics are used to classify organisms
into domains and kingdoms?
Chapter 7 Changes Over Time
Classification through Names
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
H. sapiens
Animalia
Chordata
Mammalia
Carnivora
Felidae
Felis
F. domesticus
Chapter 7 Changes Over Time
Classification through Names
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
Animalia
Chordata
Mammalia
Carnivora
Felidae
Felis
F. domesticus
Animalia
Chordata
Mammalia
Carnivora
Felidae
Felis
F. chaus
Chapter 7 Changes Over Time
Three Domains of Life
In the three-domain system of classifications, all known
organisms belong to one of three domains–Bacteria,
Archaea, or Eukarya.
Bacteria
Archaea
Eukarya
Protists
Fungi
Plants
Animals
Chapter 7 Changes Over Time
Levels of Classification
As you move down the levels of classification, the number of
organisms decreases. The organisms at lower levels share
more characteristics with each other.
Chapter 7 Changes Over Time
End of Section:
Classifying
Organisms
Chapter 7 Changes Over Time
Section 5:
Branching Trees
How does a branching tree diagram show
evolutionary relationships?
Chapter 7 Changes Over Time
A Branching Tree
Branching trees such as this show relationships between
groups of organisms. It also shows the order in which
specific characteristics may have evolved.
Chapter 7 Changes Over Time
Shared Derived Characteristics
A branching tree diagram shows evolutionary relationships
by grouping organisms according to shared derived
characteristics.
Amphibians
Fishes
Reptiles
Egg with shell
Invertebrates
Four limbs
Backbone
Ancestor of animals
Chapter 7 Changes Over Time
End of Section:
Branching Trees