- 1 Lecture 1, intro to Understanding Evolution
- 2 Lecture 2, Variation in Population
- 3 Lecture 3, Darwinian scheme of evolution
- 3.1 Erasmus Darwin, 1731 - 1802
- 3.2 James Usher
- 3.3 Catastrophism vs. Uniformitarinism
- 3.4 Darwin's voyage
- 3.5 Natural selection and struggle for evolution
- 3.6 Alferd Russel Wallace
- 3.7 Observations of evolution
- 3.8 Important points
- 4 Lecture 4, Gregor Mendell
Lecture 1, intro to Understanding Evolution
Basics of science
discuss term scientist, what is is based off, what biology is, note taxonomy
- Observation, scietific method, explain phenomena
- why things happen, allude to puzzle
- explanations in science are hypotheses
- Tentative, only natural causes explain natural phenomena
- Science uses inductive reasoning
- A hypothesis must be testable
- Tested by conducting experiments of observations
- works specifically to generally.
- Deductive reasoning, if hypothesis is correct then we can expect a specific outcome.
Observation - question - hypothesis - experiment - conclusion
- (Insert scientific method chart)
- key points of method
- a theory is a set of related hypothesis supported by evidance tat explains some aspect of natural world
- Scientific claims are subject to revision in light of new evidance
- Results must be reproducable
- Sciencetific claims must be falsifiable (white swan example)
- Hypothesis with several experimental tests are "well supported and highly corroborated.
Lecture 2, Variation in Population
- Living things are organised hierachically
- Basic heriditry unit
- Every inherited trait has one gene
- Most traits have more than one gene
- complete set of genes in given spcie
- Each individual has two copies of every gene
-One from mom, one from dad, mention alleles
- These may be same or different
- Somge genes have only one allele, most have two +
- Human ABO blood, 4 alleles
- bullfrogs with many legs
- Only appeared one year
Minnesota and other states, 19995
- Deformed in many species
- Appeared in later years
- Many populations affected
- Some went extinct
How is this explained?
May have been caused by a teratogen (agent in environment that causes birth disorders) Many teratogens have been identified
- chemicals, radiation, parasites, temperature extremes, diet problems, lack of oxygen
- Sleeping pill/tranqualizer banned in US and other countries.
- 1961 - Proven to cause "seal limbs"
- 1962 - Banned worldwide
- 1997 - Legalised for leprosy treatment
- Test environmental modification
- Mention that genetic makeup is not altered, not inhereted
- Another hypothesis
- allele: One variant of gene
- dominant ones are always expressed
- None-dominant ones (recessive) are repressed with a dominant allele
- Carrier, normal apperance, one dominant, one recessive
Ellis Van Creveld syndrome
Six fingers, short limbs, malformed hearts
- suprisingly common in Amish (mention founder effect)
Lecture 3, Darwinian scheme of evolution
Erasmus Darwin, 1731 - 1802
- English physicial, natural philosopher, "psychologist, inventer and poet
- CD's grandfather
- Wrote "Zoonomia, or the laws of organic life"
- Presented evolutionary ideas in poetry
- Did NOT propose a method, but discussed how life could have "evolved" from one filament
- Annals of the torah from beginnning of world
- Calcuated date "23 Oct BCE"
- Sept 21, 2004 BCE in gregorian calender
Catastrophism vs. Uniformitarinism
Conflicting geological theories
- Geological features were shaped during dramatic upheavals, not gradual changes
- George Curvier
- Early explanation for fossil record
- Curvier's hypothesis is mixed with biblical catrasphies like flood
- Charles Lyell
- Gradual changes over a long period of time
- Argued that forces we see today worked at the same time
- Printed "principles of geology"
- 22 year old Darwin left on a 5 year boyage on HMS beagle
- Unpaid naturalist and companion to Robert Fritzgerald (explain class division)
- Took Lyell's book "Principles of Geology with him
- Darwin obsered ancient forms had same basic body forms.
- Saw relationships as evidance organisms changed over time
- Living species had ancestors now extinct
- galapagos islands, 600 miles west of Ecuador
- Each of 13 large islands had another subspecie
- Each tortise specie was unique to its environment
- Subspecies closely related to others and tortises on mainland
- A dozen species live on Galapagos, some only on one island
- Beaks adapted to specific diets
- Darwin observed finches on many islands and other finches on mainland
- Initially proposed that species changed over geological distance
- Apparently, one specie gave rise to many others
Mechanisms of evolution
Darwin returned in 1836, convinced observations could only be explained by "descent with modification". Did not know mechanism quite yet.
- Late 1830's, darwin studied animal and plant breeding
- domestic breeds revealed great variability hidden in single specie (link to lecture 8)
- Breeders with artificial selection bred only types they found interesting.
- Darwin pondered how traits were inhereted, initially accepted Lamarkian scheme of evolution.
1766 - 1834
- Essay, "Principle of population"
- reproductive capacity of humans exceedes food supply
- Humans compete for "necesseties of life"
- Competition causes vice, misery, famine, and war
- Called malthusianism
Natural selection and struggle for evolution
- Darwin read malthus's work, and came to conclusion that struggle for survival resulted in natural selection
- THERE IS NO PLAN for evolution
Alferd Russel Wallace
- British biologist, explored geography and anthropology
- collected extensivly
- Developed theory of natural selection independently, almost same as Darwins
- developed idea while stricken by malaria
- Kept belief, later became whats known as "Thiestic evolutionist"
- 1844 - Darwin goes to Lyell for advice. Lyell urges him to publish. He doesn't.
- 1858 - Gets letter from wallace. Darwin and Wallace recieve credit together, and present before Linnaen essay
- 1859 - finially publishes "Origin of Species
Observations of evolution
- Exponental population growth - Organisms have such great fertility that they exponentally increase in population if all individuals reproduce sucessfully.
- Populations tend to remain mostly stable
- Resources are limited.
- Individuals tend to vary slightly
- Variation is inevitiable.
- From 1, 2, and 3, we can conclude that there is a struggle among organisms to survive.
- From 4 and 5, we can conclude that individuals vary.
- From all the above, we can observe that unequal survival and reproduction eads to adaptation, and unequal adaptation leads to gradual change. Favorable characteristics tend to accumulate in a population.
- Natural selection has no plan or purpose
- Individuals do not evolve. Populations do.
- Natural selection is an analogy to artifical slection
- Breeders aim at specific results, natural selection aims for survival
Lecture 4, Gregor Mendell
1856 - Studied inheritance in peas.
- Believed paretn's traits "blended" into offspring
- Nobody knew anything about genes, chromosomes, or meiosis
- All mendell worked with were visible characteristics, colour, shape, size.
- Traits are inhereted as units or "factors". Factors are now known as genes.
- Teses factors come in pairs (now called alleles)
- Factors segregate before reproduction (gametes)
- Factors do not blend.
He was mostly correct, examples of where he was wrong later.
- 1859 - Origin published
- 1866 - Mendell publishes work in Latin in an obscure journal... and is forgotten.
- 1882 - Chromosomes discovered
- 1887 - august weismann suggests process that halves chromosome number
- 1990 - Meiosis is discovered, and Mendel's work is rediscovered
- 1903 - Walter Sutton proposed that the physical location of Mendel's factors must be the chromosome
From there, the modern theory of evolution kicks off.