1. Evolution Darwin’s Theory of Evolution Evolution of Populations
The History of Life
Classification

2. Evolution = Theory = “Change over time”
The process by which modern organisms have descended from ancient organisms
A verb!!! NOT a noun!!!
Theory =
A well-supported testable explanation of phenomena that have occurred in the natural world
Based on measurable observations of the natural world

3. Microevolution – Macroevolution –
Describes the details of how populations change from generation to generation
Describes how new species originate
Macroevolution –
Describes patterns of changes in groups of related species over broad periods of geologic time
Determines the phylogeny (evolutionary relationships) among species/groups of species

4. Darwin’s Theory of Evolution

5. Voyage of the H.M.S. Beagle (1831-1836)
As Darwin made observations on his journey he wondered about…
Why were many plants and animals well suited to the habitat in which they were found?
Puzzled by where plants and animals lived and did not live.
Were fossils related to species still around today?
Darwin was also intrigued by the tortoise diversity on the Galapagos Islands.

6. Ideas that shaped Darwin’s Thinking
Hutton’s theory of Geologic Change (1785) –
Earth is shaped by geological forces that took place over extremely long periods of time
Earth is millions of years old (not thousands)
Thomas Malthus (1798) –
Predicted that the human population will grow faster than the space and food supplies needed to sustain it

7. Ideas that shaped Darwin’s Thinking
Jean-Baptiste Lamarck (1809)–
1st to propose a theory of how organisms change over time (Use and disuse, Inheritance of acquired traits, tendency toward perfection)
Incorrect theory  an organism’s behavior has no effect on heritable characteristics!!!
Lyell’s Principles of Geology (1833) –
Processes occurring now have shaped Earth’s geological features over long periods of time.

8. On the Origin of Species
Darwin did not rush to publish (waited 25 years!)
Published his work because of Alfred Wallace (who had similar theories)
1859 – On the Origin of Species
Caused a controversy because the theory radically challenged church doctrine

9. Evolution by Natural Selection
Struggle for Existence –
Members of each species compete to obtain food, living space, and other resources necessary for life
Survival of the Fittest –
Individuals that are better suited to their environment survive and reproduce most successfully.
Fitness  ability to survive and reproduce
Adaptation  any inherited characteristic that increases an organism’s chance at survival

10. Evolution by Natural Selection
Descent with Modification –
Species today look different from their ancestors
Natural selection produces organisms that have:
Different structures
Establish different niches
Occupy different habitats
All living organisms are related to one another

11. Evidence of Evolution Evidence includes: The fossil record
Geographic distribution
Homologous and Analogous structures
Similarities in Embryology
Similarities in Biochemistry
(review the activities done for each of these)

12. Evolution of Populations

13. Genetics and the Environment
The characteristics of organisms  not solely determined by inherited genes
Determined by interaction between genes and the environment
Genes provide a plan for development  how the plan unfolds also depends on the environment

14. Genes and Variation 2 main sources of genetic variation:
Mutations
Gene shuffling during sexual reproduction
Gene pool  all genes (and alleles) that are present in a population
Relative frequency  # of times an allele occurs in a gene pool (given as a percentage)
Evolution is any change in the relative frequency of alleles in a population

15. Natural Selection and Evolution
Natural Selection never acts directly on genes
Works on the entire organism…can only affect which individuals survive and reproduce
If an individual dies  does not pass on genes
ALSO…Individuals do not evolve…Populations evolve as the gene pool changes because of the relative frequency of the alleles changes

16. Natural Selection and Genetic Change
Single-Gene traits  leads to changes in allele frequencies (thus to evolution)
Natural Selection on Polygenic Traits  leads to changes in the distribution of phenotypes (3 ways):
Directional Selection
Stabilizing Selection
Disruptive Selection

17. Directional Selection

18. Stabilizing Selection

19. Disruptive Selection

21. How do Populations Evolve?
Natural Selection in not the only source of evolutionary change
Genetic drift 
Individuals that carry a particular allele may leave more descendents BY CHANCE.
Over time, a series of chance occurrences can cause an allele to become common in a population
A new species can result if there is enough of a genetic difference between the original population and the new population

22. Evolution vs. Genetic Equilibrium
Hardy-Weinburg Principle  allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change
Constant allele frequencies = genetic equilibrium

23. Hardy-Weinburg
In order to maintain genetic equilibrium there are several conditions that must be met:
Random mating
Large population
No movement into or out of the population
No mutations
No Natural Selection
Refer to the activity for review

24. The Process of Speciation
Formation of a new species (organisms that breed and produce fertile offspring)
As new species evolve, populations become isolated from one another
Reproductive isolation  members of 2 populations can no longer interbreed and produce fertile offspring

25. Isolating Mechanisms
Behavioral Isolation  differences in courtship or other reproductive strategies that involve behavior
Geographic Isolation  2 populations are separated by geographic barriers
Temporal Isolation  2 or more populations reproduce at different times of the year

26. Case Study: Darwin’s finches
Evolution of Darwin’s finches 
Founders arrive
Separation of populations
Changes in the gene pool
Reproductive Isolation
Ecological Competition
Continues Evolution

27. Patterns of Evolution 4 main patterns 
Divergent Evolution: 2 or more species originate from a common ancestor
Convergent Evolution: 2 unrelated species that share similar traits (independent adaptation to the environment)
Parallel evolution: 2 related species (lineages) that have made similar changes after the common ancestor
Coevolution: evolution of one species in response to new adaptations in another (predator/prey relationship)

28. Divergent Evolution

29. Convergent Evolution

30. Parallel evolution

31. Coevolution

32. Macroevolution 2 distinct theories: Gradualism Punctuated Equilibrium
Evolution occurs by the gradual accumulation of small changes
Punctuated Equilibrium
Evolutionary history consists of geologically long periods of stasis with little or no evolution, interrupted by geologically short periods of rapid evolution

33. Gradualism

34. Punctuated Equilibrium

35. The Origin of Life: Chemical Evolution
The following is a hypothesized order of events that led to life on Earth:
The Earth and its atmosphere formed
Outgassing of the molten interior (CO, CO2, H2, N2, H2O, S, HCl, HCN)
The primordial seas formed
Complex molecules were synthesized
Oparin/Haldane and Miller experiments

36. Life on Earth (continued)
Polymers and self-replicating molecules were synthesized
Organic molecules were concentrated and isolated into protobionts
Primitive heterotrophic prokaryotes formed
Primitive autotrophic prokaryotes were formed

37. Life on Earth (continued)
Oxygen and the ozone layer formed and abiotic chemical evolution ended
Eukaryotes formed (“endosymbiotic theory”)
Originated from a mutually beneficial association among various kinds of prokaryotes
Mitochondia, chloroplasts possess their own DNA, reproduce independently of the cell, resembles bacteria and cyanobacteria

38. Standard Classification
Developed by Carolus Linnaeus in the 18th century
Organizes organisms into groups and subgroups based on evolutionary relationships
Often revised when new relationships are discovered (DNA evidence)
Example: Pseudocalanus spp.

39. Classification levels:
Kingdom (broad)
Phylum
Class
Order
Family
Genus
Species (specific)