Transcript Section 2: Evidence of Evolution

Section 2:
Evidence of Evolution
Evidence of Evolution
Evidence
of
Evolution
Similar body
structures
Comparative
anatomy
Patterns in early
development
Homologous
structure
All vertebrates
have a tail and rows
of slits in
their throats.
DNA and proteins
Similar DNA might
Mean that they
Evolved from the
Same acestor
Fossils
1.Molds and casts
2.Petrified fossils
3.Trace fossils
4preserved remains
FORMS OF EVIDENCE
1.
2.
3.
4.
Similar body structures
Patterns of early development
DNA sequences
Fossils
Body structures

Comparative
anatomy: The
comparison of the
structures of different
organisms.

Homologous
structures: Body parts
that are structurally
similar in related
species.
COMPARATIVE ANATOMY
HOMOLOGOUS STRUCTURES
Early Development

In early development, all
vertebrates have a tail
and tiny slits in their
throats.
DNA Sequences

The DNA sequences of different species
are similar.
Fossils

4 types
Molds
and casts
Petrified Fossils
Trace Fossils
Preserved Remains
Molds and Casts
Petrified Fossils
Trace fossils
Preserved Remains
Learning from Fossils
The fossil record provides evidence about
the history of life and past environments
on Earth.
 Scientists use fossils to study the rate at
which evolution has occurred.

Past environments

Fossils can show how an environment has
changed: EX. Coal in Antarctica – coal can
only form from the remains of plants that
grow in warm regions. (hmmm….)
Gradualism



Scientists are not sure how rapidly species
change.
Gradualism proposes that evolution occurs.. but
it happens steadily – tiny changes in a species
gradually add up to major changes over long
periods of time.
Fossil record show sudden change (lack of
intermediate forms) – incomplete fossil record?
Punctuated Equilibria
This hypothesis states that species evolve
quickly during relatively short periods.
 Most scientists think that evolution can
occur gradually at some times and more
rapidly at others.
