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Change Over Time- 7th Grade
Ms. De Los Rios
Essential Question:
How do Life Forms Change over time?
What is Evolution?
What Evidence Supports Evolution?
Evidence of Evolution
Pgs. 378-383
Evolution- Change over time. The
process by which modern organisms
have descended from ancient
Gene –a sequence of DNA that
determines characteristics or traits
in an organism and are passed on
from parent to offspring.
Homologous structures –
that are similar in different species
and that have been inherited from
a common ancestor.
My Planet Diary pg. 378
Moving On Up
In 2004, researchers on Ellesmere Island, Nunavut, in the Canadian Arctic,
found a fossil that provides information about when fish first came onto land.
The fossil, called Tiktaalik, is 375 million years old. Tiktaalik has
characteristics of both fish and four-legged animals. Like other fish, it has
fins. However, the fins have interior bones that helped push the animal up in
the shallow waters close to shore to find food. The discovery of Tiktaalik has
provided new fossil evidence to help scientists understand the relationship
between marine vertebrates and land vertebrates.
1. What characteristics does Tiktaalik have that are like a fish and a
four-legged animal?
2. Do you think Tiktaalik spent most of its time on land or in water?
Online Resources
Charles Darwin
Human Evolution
What is Evolution? Pg. 379
The diversity of life today and in the past can be
explained by Evolution.
Evolution is change over time.
Over millions of years, evolution has resulted in organisms no longer
living as well as the ones alive today. By understanding evolution, we
can begin to understand the history of life on Earth.
The scientific theory of evolution explains how
living things descended from earlier organisms.
Assess Your Understanding
pg. 379
Wooly Mammoth are no longer living,
But they share a common ancestor
With Asian elephants.
List one similarity that you can see
between these two organisms. Then
list one difference.
I get It! Now I know that the scientific theory of evolution
What Evidence Supports Evolution? Pg. 380
How do scientists know that organisms change over time?
They rely on
4 types of evidence that support the theory of evolution
Fossils, similarities in DNA and protein structures, similar body
structures, and patterns of early development all provide evidence
that organisms have changed over time.
FOSSILS pg. 380
By examining fossils, scientists can infer the structures of ancient/ old
organisms. The fossil record provides clues about how and when
new species evolved and how organisms are related.
r. 2 p.
Jurassic Park
Fig. 2 A
Florida Fossil pg. 380
How do these jawbones look
How do they help to confirm the
theory of evolution?
Similarities in DNA and Protein Structures pg. 381
Why do some species have similar body structures or similar
patterns of development?
Scientists infer that species inherited many of the same genes from a
common ancestor.
Genes are DNA sequences that
determine an organism’s characteristics.
The DNA bases along a gene specify what type of protein will be
produced. Therefore, scientists can also compare the order of amino
acids in a protein to see how closely related two species are.
Evidence from DNA and protein structure has confirmed conclusions
about evolutionary relationships among organisms based on fossils,
embryos, and body structure.
Apply It! Pg. 381
Section of Cytochrome c Protein in Animals
The table shows the sequence of amino acids in one region of a protein,
cytochrome c, for five different animals. Each letter corresponds to a different
amino acid in the protein.
1. Which species is most
distantly related to the
2. Explain how amino
Acid sequences provide
Information about
Evolutionary relationships
Among organisms.
Similarities in Body Structure pg. 382
An organism’s body structure is its basic body plan, which, in
vertebrates, includes how its bones are arranged.
• Fishes, amphibians, reptiles, birds, and mammals all have an
internal skeleton with a backbone.
•This similarity provides evidence that these animal groups
evolved from a common ancestor.
homologous structures are similar structures that related species
have inherited from a common ancestor.
Fig. 3 Evidence of Evolution pg. 382
Homologous Structures
The bones in a bird’s wing, a dolphin’s flipper, and a dog’s leg
have similar structures. Which bones in the dog's leg match
those in the flipper and which match those in the wing?
Using the drawing of the dog’s leg as a guide,
Color in the matching bones in the bird’s wing and
the dolphin’s flipper with the appropriate colors.
Similarities in Early Development pg. 383
Scientists also infer evolutionary relationships by comparing the
early development of different organisms. Similarities can further
suggest that species are related to a common ancestor.
A look at the organisms show that:
•They look similar in early stages
of development.
•All the organisms have a tail.
•They also have a row of tiny slits
Along their throats.
The similarities suggest that these
Vertebrate species are related and
Share a common ancestor.
Similarities in Development pg. 383
These four organisms all look
similar during their early
development. What are
similarities and differences
among them?
1. Circle at least two
similarities shared by all
four organisms.
1. What are some differences
between the organisms?
Assess Your Understanding pg. 383
1a. __________________________structures
are structurally similar body parts in related
b. Bats and birds both have wings. What kinds
of evidence might show whether or not bats
and birds are closely related? Explain.
I get It! Now I know that the theory of evolution
is suported by evidence that includes