Evolutionary Processes

1. Evolutionary Processes

2. Human Chromosomes

3. Evolution
• Evolution is change in gene (allele)
frequencies in populations over time.

4. Species
Species: a group of organisms that,
under normal circumstances, can breed
with each other and have viable, fertile
offspring.

5. Dogs and Wolves = Same Species

6. Horse x Donkey =

7. Mule
• Mules are a hybrid
species. While they
have positive
features of both
parents they are
almost always
sterile: i.e. they
cannot reproduce;

8. (male) Lion x (female) Tiger

9. Ligers

10. (male) Tiger x (female) Lion

11. Tigon

12. Species, Population and Evolution
Important to remember: evolution
occurs within populations, NOT
individuals.

13. Breeding Population
• Breeding populations are populations
within a species that are genetically
isolated from each other, typically by
geography.
• Gene pool = all the genes carried by all
the members of such a group.

14. Gene Frequency
• Gene frequency : how frequently a
particular gene is found within a
given population.
• For instance, you could say that
20% (or 30% or 90%) of a
population carry a particular gene
(allele)

15. Means of Evolution
• Mutation
• Natural Selection
• Genetic Drift
• Gene Flow
• Artificial Selection

16. Mutation and Evolution
• Mutations are random changes in
genetic material that occur within
individuals.
• Mutations are what allow for the
emergence of new traits within a
population.

17. Natural Selection
• Natural selection: certain traits provide
an advantage in a particular
environment. Individuals with such traits
are more likely to pass on their genes to
offspring.
• Natural selection is sometimes
summarized as “the survival of the
fittest.”

18. Genetic Drift
Genetic drift represents changes in
gene frequencies due to random
chance.

19. Example of
Genetic Drift: The Founder’s Effect
Original Population
= 50% Blue eyes and 50% Brown eyes
From this group a small population separate.
Coincidentally, there is a high frequency of
brown eyes in this group

New Group
= 80% Brown Eyes and 20% Blue Eyes

20. Gene Flow and Evolution
Gene Flow: when
new individuals
enter a breeding
population and add
their genes to the
gene pool.

21. Artificial Selection
• Artificial Selection represents breeding
other organisms in order for them to
display particular traits.

22. Speciation
• Speciation refers to the emergence of two
or more species from a common
ancestor.
• Species represent genetically isolated
groups because of their inability to breed
with each other.

23. Language exercise
• Italian: Pietra
• Portuguese: Pedra
• Spanish: Piedra
• Catalan: Pedra

24. Language exercise
Latin: Petra
  
Italian: Pietra Portuguese Pedra
Spanish: Piedra Catalan: Pedra

25. Common Ancestor
• Common ancestor: the ancestor of two
or more different species.

26. Shared derived characteristic
• Shared derived characteristic: features
shared by two or more taxonomic
groups that are derived from a common
ancestor.

27. Horse

28. Onager

29. Zebra

30. Donkey

31. Hyracotherium fossil

32. Evolution of Equines

33. “Zonkey” (Zebra-Donkey
Hybrid)

34. Homologous Structures

35. Analogous Structures