SCIENCE 10 - THEORIES of EVEOLUTION_powerpoint

Theories

2. THEORIES
OF
EVOLUTION

3. Learning Objectives:
1.Explain the occurrence of
evolution.
2. Trace the history of the
theory of evolution.
3. Identify the different types
of evolution.

4. What is a THEORY?What is a THEORY?
A theory is an idea or an
assumption or a hypothesis
that gives explanation to a
problem or a question that is
still not proven to be a
scientific fact, truth, principle
or law.

5. ANCIENT PHILOSOPHERS
 ANAXIMANDER – proposed that
animals could transform from one
kind to another.
 EMPEDOCLES – thought that
animals were combinations of
different parts.

6. PIERRE – LOUIS MOREAU
de MAUPERTUIS
Proposed that
spontaneous
generation (living
things developing
from nonliving) and
extinction (the dying
out of species).

7. GEORGE – LOUIS LECLERC
- Considered but
ultimately rejected the
idea of several species
having a common
ancestor. He believed in
the idea of spontaneous
generation from organic
molecules.

8. ERASMUS DARWIN
- Charles Darwin’s
own grandfather
who published his
own speculations
on evolution in his
book Zoonomia.

9. CAROLUS LINNAEUS
-observed that there
was a variation among
species and used this
to create his taxonomy,
a classification system
we still use for
organisms.

10. MODERN THEORIES
OF EVOLUTION
A.The Theory of Inheritance of
Acquired Characteristics
( Lamarckism)
B. The Theory of Evolution By
Natural Selection (Darwism)

11. OTHER THEORIES OF
EVOLUTION
The Germ Plasm Theory or
Neo – Darwism
 Theory of Evolution By
Mutation/Mutationism
 The Synthetic Theory of
Evolution

12. ACTIVITY
Directions: Describe the different theories of
evolution in a tabular form. Use the format below:
THEORIES OF
EVOLUTION
PROPONENT OR
PHILOSOPHER
DEFINITION EXAMPLES THAT
PROVES THE
THEORY
Ex.
The Theory of
Inheritance of
Acquired
Characteristics
( Lamarckism)
Jean – Baptiste
de Monet,
chevalier de
Lamarck

13. Charles DarwinCharles Darwin
Father of Evolution
Proposed a mechanism for
evolution, natural selectionnatural selection
Darwin went on a 5-year trip
around the world on the
ship, the HMS Beagle
As the ship’s naturalist, he
made observations of
organisms in South
America and the
Galapagos Islands

15. Darwin’s Finches

16. Natural Natural
SelectionSelection
According to natural
selection, organisms
that are best adapted to
an environment survive
and reproduce more
than others

17. Darwin’s Theory of Natural
Selection occurs in four steps:
Overproduction
Variation
Competition
Selection

18. 1. Overproduction1. Overproduction
Each species produces more
offspring that can survive

19. 2. Variation2. Variation
Each individual has a
unique combination of
inherited traits.
Adaptation:Adaptation: an inherited
trait that increases an
organism’s chances of
survival

20. What adaptations do you see?

21. What adaptations do you see?

23. Why is Variation Important?
Because the environment changes.
The more variation variation withinwithin a species a species, the
more likely it will survivesurvive
EX: If everyone is the same, they are all
vulnerable to the same environmental
changes or diseases
The more variation of variation of types of types of speciesspecies in
an habitat, the more likely at least some some
will survivewill survive
EX: Dinosaurs replaced by mammals

24. Which community has a better Which community has a better
chance of surviving a natural chance of surviving a natural
disaster?disaster?
Community ACommunity A Community BCommunity B

25. Peppered Moth
Which moth will the bird catch?
A
B

26. 3. Competition3. Competition
Individuals COMPETE for limited
resources:
Food, water, space, mates
Natural selection occurs through
“Survival of the fittestSurvival of the fittest”
FitnessFitness: the ability to survive long enough to
reproduce
Not all individuals survive to adulthood

27. 4. Selection4. Selection
The individuals with the best traits / best traits /
adaptations will survive and have the adaptations will survive and have the
opportunity to pass on it’s traitsopportunity to pass on it’s traits to
offspring.
Natural selection acts on the phenotype
(physical appearance), not the genotype
(genetic makeup)
Ex: When a predator finds its prey, it is due
to the prey’s physical characteristics, like
color or slow speed, not the alleles (BB, Bb)

28. Individuals with traits that are not
well suited to their environment
either die or leave few offspring.
Evolution occurs when good traits good traits
build up in a populationbuild up in a population over many
generations and bad traits are bad traits are
eliminated by the death of the eliminated by the death of the
individualsindividuals.

29. Descent with ModificationDescent with Modification
Descent with Modification Descent with Modification – each
living species has descended, with
changes, from other species over
time.
Common Descent Common Descent – all living
organisms are related to one another