4 Evolutionary Processes

Evolutionary Processes

1. Evolutionary Processes

2. Human Chromosomes

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

4. Species S pecies : 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 N atural 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