Textbook Notes (290,000)
CA (170,000)
UTSG (10,000)
BIO (600)
BIO120H1 (300)
Chapter 1

Chapter 1 Study Notes

Course Code
Benjamin Wright

of 3
Lecture 1
Evolution: The Central unifying Concept of Biology
Key Concepts/ Terms:
Descent with modification
Inheritance of acquired characters
Common Ancestor
1)Origins of evolutionary thought: Before Darwin and After Darwin
2)How evolution is studied: Evolutionary History and Evolutionary mechanism
3)Evolution, fact and fiction: Misconceptions and Evolution and scientific theory
Levels of Biological Organization:
Populations (populations evolve)
1)Number One:
a.Evolution is the central unifying concept of biology
b.One of most influential concepts of western thought
c.All aspects of biology have a firm beginning in evolution
d.Made up of two revolutionary ideas that contrast
i.Changing universe concept replaced static world view
ii.Causes of phenomena in purposes but evolution has no purpose, its an inevitable
outcome of interactions between organism and their environment
e.Before Darwin many scientists challenged view of permanent and unchanging world
f. Jean-Baptiste de Lamarck presented mechanism of evolution based on inheritance of
acquired characters (change in life time then pass on changes)
i. Individuals alter their morphology and behaviour according to their environment,
then these changes are passed on (use and disuse alter organisms structure)
ii.Also believed evolution involved progression along continuum from simple to complex
forms (believed that some organisms are less complex because they havent had time
to become complex)
iii.He was wrong but introduced term evolution to scientific world
g.William Paley: Argument from design, believed that if something has a function it has a
h.Charles Darwin provided first complete theory of evolution in The Origins of Species
i.Co-discover with A.R. Wallace of the chief mechanism of evolution: Natural Selection
2)Number Two:
a.Darwin went to the university of Edinburgh to become a doctor, he dropped out in second
year and went to Cambridge to become a clergy man, thats where he got the opportunity to
join the H.M.S. Beagle (1831-1836)
i.On the voyage he reads Charles Lyells Principles of Geology
ii.Finds the Galápagos mockingbirds, doubts fixity of species
iii.He reads Malthus’ essay on the Principle of population, which he says that it struck
him that under those circumstances favourable variations would tend to be
preserved and unfavourable ones would be destroyed
iv.Took him 20 years to publish book because he knew it would be a big step in
acceptance for society and other theories before had been confronted
v.His theory of evolution took right away, theory of natural selection took some time
b.Two basic ideas of Darwins book
i.All organisms have descended with modification from common ancestor
ii.The major agent of modification is natural selection operating on variation among
c.Darwins Mechanism of Natural Selection:
i.Variation: individual variation in a population
ii.Heredity: Progeny resemble their parents more than unrelated individuals
iii.Selection: Some forms are more successful at surviving and breeding than others in
a given environment
Lines = traits Family tree Top tree shows they have a common
Line before dot = common ancestorBoth trees represent exactly the same
All organisms share same ancestors
e.Today these two ideas are studied as evolutionary history (macroevolution) and
evolutionary mechanisms (microevolution)
i.Macroevolution students interested in evolutionary relationships among organism in
terms of common ancestors (palaeontology)
ii.Microevolution students involves determining particular mechanism responsible for
evolutionary change (population biology)
f. Microevolution has shown us:
i.Populations contain genetic variation by random mutation/ recombination
ii.Populations evolve by changes in gene frequency
iii.Phenotypic changes are gradual
iv.Evolutionary diversification comes by speciation (gradual evolution of reproductive
isolation among populations)
3)Number Three:
a. Individuals do not evolve because they are born and die without any change in genetic
makeup. Populations evolve
b.Natural selection has no purpose, not even the survival of species
c.Evolution does not lead anywhere, not a higher or more advance human species
d.Darwinism has nothing to do with moral or ethical decisions
e.Evolution is considered a fact today, not a theory
f. Evolution is extremely recent, 150 years
Review and Study Questions:
1)Why is Lamarcks theory of evolution rejected by biologists today?
2)What two major contributions did Darwin make to our understanding of evolution?
3)Evolution is widely accepted by virtually all scientists. Why?
4)Why do you think the concept of evolution is poorly understood by the general public?
5)Why is evolution central to all disciplines of biology?
Recommended Readings:
Scitable- Genetics and evolutionary genetics
Berkeley- History of evolutionary thought