Evolutionary Concepts

1. GENERAL BIOLOGY 2

2. LEARNING OBJECTIVES
Explain the mechanisms that produce change in
populations from generation to generation:
1. Mutation
2. Natural Selection
3. Genetic Drift
4. Gene Flow ( Migration )
5. Recombination

3. OBSERVE THE PICTURE

4. HARDY–WEINBERG LAW
1.The law that states that in an infinitely large, interbreeding
population in which mating is random and in which there is no
selection, migration, or mutation, gene and genotype frequencies
will remain constant from generation to generation.
2.The Hardy-Weinberg equation is a mathematical equation that can
be used to calculate the genetic variation of a population at
equilibrium. The equation is an expression of the principle known
as Hardy-Weinberg equilibrium, which states that the amount of
genetic variation in a population will remain constant from one
generation to the next in the absence of disturbing factors.

5. Charles Darwin
Evolution
A process that results in
changes in the genetic
content of a population
over time.

6. Jean Baptiste Lamarck
Lamarckism
A theory of evolution based on
the principle that physical
changes in organisms happens
during their lifetime

7. Darwinism and Lamarckism
compared
Lamarckism
 An evolutionary theory
based on the principle
that physical changes in
organisms could be
transferred to their
offspring over their
lifetime — such as greater
development of an organ
or a component through
increased use.
Darwinism
 Darwin believed that an
evolutionary process undergoes
transformative alteration
through Natural Selection

8. Darwinian and Lamarckian Evolution

9. James Hutton
Principle of Uniformitarianism
Is the assumption that the same
natural laws and processes that
operate in our present-day scientific
observations have always operated
in the universe in the past and apply
everywhere in the universe.

10. MECHANISMS OF EVOLUTION
1. Natural selection
2. Mutation
3. Genetic drift
4. Gene flow (migration)
5. Recombination

11. NATURAL SELECTION
Occurs when individuals with certain genotypes are
more likely than individuals with other genotypes to
survive and reproduce, and thus to pass on their
Alleles to the next Generation. It was proposed by
two Naturalists: Charles Darwin and Alfred Russell
Wallace

12. What is an Allele?
It is one of the two or more alternative
forms of a gene that arise by mutation and
are found at the same place on a
chromosome.

13. What is a Genotype?
The genotype of an organism is its
complete set of genetic material.

14. Natural Selection in action

15. NATURAL SELECTION
1.First, the characteristics of organisms are
inherited, or passed from parent to offspring.
2.Second, more offspring are produced than
are able to survive
3.Third, offspring vary among each other in
regard to their characteristics and those
variations are inherited.

16. MUTATION
This is a change in the DNA sequence of
the gene. Mutation is a source of new
Alleles in the population. A mutation
can change one allele into another,
but the net effect is change in
frequency. The change in frequency
resulting from mutation is small, so its
effect on evolution is small also unless it
interacts with one of the other factors
such as selection.

17. GENETIC DRIFT
A change in allele frequencies in a population
from generation to generation that occurs due to
chance events. To be more exact, genetic drift is
change due to "sampling error" in selecting the
alleles for the next generation from the gene pool
of the current generation.

18. Genetic Drift in action

19. GENE FLOW
It occurs when an individual travels from one
geographic location to another and joins a different
population of the species.

20. RECOMBINATION
It occurs during meiosis when chromosomes
exchange genes. This process ultimately leads to
the formation of unique gametes with
chromosomes that are different from those in
parents. This is one of the important means to
promote and increase genetic diversity between
generations.

21. THANK YOU FOR LISTENING!
until next time…