1. Descent with modification
Evolution
Descent with modification

3. I. Biological Evolution = observable fact
A. Change in species over time
B. Change in gene frequencies from generation to generation
C. A Process of change

4. II. Proposed Mechanism for evolution
A. Natural Selection – Requires
1. Genetic diversity
2. differential reproduction by individuals with the most fit genes
3. Increase in those genes within population

5. III. Pre-Darwin Ideas A. Carolus Linnaeus (1707-1778)
1. Binomial Nomenclature Genus species
2. nested groupings into increasingly
specific categories based on morphology
3. K P C O F G S
4. Kingdom, phylum, class, order, family, genus, species
5. now we have added Domains

6. B. Stratification –
1. rock laid down in layers
2. oldest at bottom
3. fossils in strata show when organisms lived
order of appearance (now isotopic dating)
4. Older fossils more dissimilar to modern
5. species appear and disappear
6. Cuvier ( ) catastrophism
a. catastrophes destroyed species in an area
new species moved in

7. C. Lamarck ( )
1. one of many to propose that life evolves as environments change
2. first to propose mechanism
3. compared fossils showing lines of descent
a. chronological fossils show gradual change
b. leading to modern species
c. use and disuse
d. inheritance of acquired characteristics

9. III. Darwin’s Contemporaries
A. Charles Lyell ( 1797 – 1875)
1. Geologist
2. Theory of Uniformity
3. Natural processes observed today are the same as processes acting in the past
4. The rate of processes today mirror those of the past
5. contradicted young earth theory

10. B. Thomas Malthus: economist
1. war and famine result from human overpopulation
2. Other organisms also produce more individuals than can survive

11. C. Alfred Wallace ( )
1. first to publish Natural Selection as a mechanism for evolution
2. ideas nearly identical to Darwin’s
D. Charles Darwin ( 1809 – 1882)
1. Origin of Species
2. extensive evidence of
natural selection
3. Lylle, Darwin & Wallace
convinced most scientists with in 10 years

12. Origin of Species Three Main Ideas
1) Unity of Life: shared characteristics attributed to shared common ancestor
2) Diversity of Life: due to descent with modification
3) Match between organisms and environments: due to adaptation

13. IV. Darwin’s main observations/Inferences
Observations in blue
Followed by associated Inference
Inferences in yellow

14. A. Artificial selection: selective breeding
can produce visible change over a life-time
A. If artificial selection can produce rapid change….then natural selection could produce dramatic change given enough time
* Lyell suggested a time line of millions of years

15. B. Organisms produce more offspring than can survive (Malthus)
B. Survival most likely for those best fit to their environment.

16. C. members of a population vary in Inherited
traits
C. If only some organisms can survive then
those with best traits are more likely to survive
So good genes accumulate in population…
Genetic make-up of population ∆ over time =
Evolution!

19. (morphological evidence note)
Mammal neck bones =7
Bird neck bones 13-25
Giraffe neck vertebrae are each elongated…
No new bones added
Birds with short neck have curve in neck vertebrae…
not fewer vertebrae

21. VI. Natural Selection Vocab.
A. Fitness:
ability to pass on its genes
1. survive
2. mate
3. fertile offspring live to reproduce
B. Adaptation: inherited traits that improve fitness in a given environment
1. individuals can NOT adapt its genetic!!
2. only populations adapt over generations

22. VII. Theory of Evolution
A. speciation – one species branches into 2 new species (ancestral species gone)
B. Adaptive radiation –1 species gives rise to many species (common after mass extinctions)
1. individuals disperse to new environments
2. adapting to new environment causes them to change

23. C. Universal Common Ancestor – all started from some single celled organisms
1. ‘the unity of life’
2. universal genetic code DNA, RNA
3. shared genes (homeotic genes)
4. Semiconservative replication
5. transcription/translation (Met)
6. shared proteins(DNA and RNA polymerase)

24. VIII. Main Branches of Evidence
A. Direct observation – species change over time
1. Bacteria develop antibiotic resistance

26. 2. Weeds develop resistance to roundup
Figure 1. Number of weed species with glyphosate resistant populations and number of states with glyphosate-resistant weed populations.
Source: Heap, 2009.

28. 3. Grant’s finch research
a. recorded beak depth of all finches on an island over 30 years

29. B. Homology: similarities resulting from
common ancestor
1. Homologous Structures
a. anatomical features
b. same underlying structure
c. may have adapted to different function

30. d. embryo homology may be lost in adult
1. pharyngeal arches – all chordates
2. post anal tail – all chordates

31. e. Chordate limbs : same bones just different shape due to different function of appendage

32. 2. Vestigial Structures : inherited from ancestor but no longer used
a. explains presence of useless structures
b. pelvic girdle & femur in whale & snake

33. C. Human vestigial structures

34. 3. molecular homologies: same DNA/ protein
a. all organisms homologous DNA structure
b. Many homologous DNA genes
1. some have developed a new function
2. some still same function
a. genes for ribosome subunits homologous between humans and bacteria
3. some genes vestigial

35. C. Fossil Record
A. document formation of new species by sequential fossils

36. D. Biogeography 1. Geographic distribution of species
2. endemic species :
a. ancestor from mainland
b. adaptive radiation
c. island species all share
1. homologous structures
2. homologous DNA/proteins
d. homologies shared with a mainland species
3. Similar species from different continents not genetically similar
(convergent evolution)