Evolution lectures1&2 2012 slideshare

SBS 110 - Evolution

SBS 110 - Evolution

“Nothing in Biology Makes Sense Except in the Light of Evolution”

Theodosius Dobzhansky 1973

http://en.wikipedia.org/wiki/Theodosius_Dobzhansky

http://en.wikipedia.org/wiki/Theodosius_Dobzhansky

Course Outlineand Timetable

Recommended Reading

Paperback 352 pages (2010)Publisher : Profile Books

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Paperback 416 pages (Jan. 1, 2007)

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Paperback 596 pages (11 Aug 2005)

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Lecture 1: Introduction and some historical perspectives

1809—1882

Early ideasFixity of species or change?


350 B.C. Aristotle:individuals in a “Species” are identical and unchanging



1749 Buffon Histoire Naturelle encyclopedia: The earth is very old. Species change.




1785 Hutton. Geologist: Uniformitarianism: Changes in nature are gradual.




1785 Hutton. Geologist: Uniformitarianism: Changes in nature are gradual.

1798 Cuvier : Fossils show extinct species (due to catastrophe). Species don’t change.

3 Schools of evolutionary thought

1. Linnaeus:1700s

2. Lamarck: 1744—1829

3. Darwin & Wallace: 1800s

Carolus Linnaeus (1707—1778)

• Swedish

• 180 books classified nature: “revealing the order of life created by God.”

• Devised the binomial naming system: Genus species

• Thought that species do not change.


3 Schools of evolutionary thought• Linneaus: each species was

separately created.

J-B. de Lamarck (1744—1829)

• Worked most of his life at the Muséum d’Histoire Naturelle (Paris)

• He promoted the idea that species change.


1. Linnaeus:1700s

2. Lamarck: 1744-1829


3 Schools of evolutionary thought• Linneaus: each species was

separately created.


• Lamarck: characteristics acquired by an individual are passed on to offspring.

• Linneaus: each species was separately created.

Giraffe necks• Lamarck: stretching giraffes

lengthened their necks to reach tree-top vegetation. This acquired characteristic is passed to offspring.

• Darwin & Wallace: giraffes with long necks out-compete those with short necks.


1. Linnaeus:1700s

2. Lamarck: 1744—1829


Thomas Malthus (1766-1834)

Published on Human population growth:Human populations increase faster (geometrically) than food production (increases arithmetically)

Ideas strongly influenced Darwin & Wallace

Charles Lyell (1797-1875)A geologist and strong proponent of uniformitarianism.

Ideas influenced Darwin and Wallace

Charles Lyell (1797-1875)

Uniformitarianism. 4 ideas:

A geologist and strong proponent of uniformitarianism.



Uniformitarianism. 4 ideas: • Accepted by all scientists:





1. Natural laws are constant across space and time





1. Natural laws are constant across space and time2. Principle of parsimony: try to explain the past by

causes now in operation without inventing extra, fancy, or unknown causes, however plausible in logic, if available processes suffice.







• Debatable:







• Debatable:3. Change is slow, steady, and gradual.







• Debatable:3. Change is slow, steady, and gradual.4. Change is evenly distributed throughout space and time.



Darwin & the Voyage of the Beagle

1831-1836

Galápagos finches

• Analysis of these finches led to the hypothesis that they were derived from one ancestral species arriving from the mainland to populate and diversify across the islands (adaptive radiation).

Darwin1837

Charles Darwin (1809-1882)

• Darwin at about 30 years old, and three years back from his voyage aboard HMS Beagle.

• The Origin of Species was published several decades later in 1859 (prompted by competition from Alfred Russel Wallace).

Alfred Russel Wallace (1823-1913)

• Wallace in his thirties. (National Portrait Gallery, London.)

• In 1858 he came up with similar ideas to Darwin about the mechanism of evolutionary change

Read at the Linnean Society

Evolution by natural selection

Under optimal conditions, populations indefinitely increase in size.



Because they do not: * either not all animals reach maturity * and/or some animals breed less




Individuals within a population differ (natural variation)




Individuals within a population differ (natural variation)These differences (traits) may affect survival/reproduction




Individuals within a population differ (natural variation)These differences (traits) may affect survival/reproductionTraits are heritable: passed on from parents to offspring




Individuals within a population differ (natural variation)These differences (traits) may affect survival/reproductionTraits are heritable: passed on from parents to offspring

Advantageous traits lead to increased survival of certain lineages








• Darwin & Wallace: viewed evolution as descent with modification.







(1859) "The Origin of Species"

A scheme or system of ideas or statements held as an explanation or account of a group of facts or phenomena; a hypothesis that has been confirmed or established by observation and experiment, and is propounded or accepted as accounting for the known facts.

theory |ˈTHēərē, ˈTHi(ə)rē|noun ( pl. theories )

Darwin's theory of evolution by natural selection

(Oxford English Dictionary)

Darwin's Theory of Evolution (1859)"The Origin of Species"


• There is inherited variation within species.



• There is competition for survival within species.




• Natural selection is the process whereby genetically inherited characteristics become more or less common in a population as a function of the differential reproductive success of the bearers of these characteristics.




• Natural selection is the process whereby genetically inherited characteristics become more or less common in a population as a function of the differential reproductive success of the bearers of these characteristics.

•This process occuruing independently on two populations of a single species leads to the accumulation of differences between the populations - and ultimately to speciation.

• But environmental conditions change: What was advantageous yesterday may be a disadvantage today.

• And evolution also occurs by: • genetic drift• sexual selection• artifical selection (selective breeding)

Natural selection leads to adaptive change

Summary of Lecture 1

Ideas on how the diversity of life was/is produced date back to the ancient Greeks

These ideas developed considerably in the 1800s, culminating in the Theory of Evolution by Natural Selection

Lecture 2

Darwin’s evidence for evolution

and

“Neo-Darwinism” or “The Modern Synthesis”


1. The Fossil Record



2. Comparative Anatomy




3. Comparative Embryology




3. Comparative Embryology4. Vestigial Structures





5. Domestication (artificial selection)


1. The Fossil Record: Paleontology

Random order Reality: there is

sequential order to the fossil record

Lecture 5

1. The Fossil Record: Paleontology

Random order Reality: there is

sequential order to the fossil record

Lecture 5


2. Comparative Anatomy3. Comparative Embryology4. Vestigial Structures



2. Comparative anatomy

• Correspondence between parts and comparison of forelimbs among four vertebrates.

Diversity of type, unity of pattern

• Although these vertebrate species differ, the underlying pattern of the forelimb is fundamentally the same.

Homology and analogy

• Homology - vertebrate forearms: the bat wing, mouse forearm, and human arm are homologous structures as all are composed of similar bones inherited from a recent common ancestor.

Homology and analogy

• Analogy: The wings of bats, butterflies, and birds evolved independently, not from a recent common ancestor. But they have a similar function, flight, and so are analogous.

Morphological series - evolution of limbs from fins

• Note homology of structures







• Embryonic retention of ancestral characteristics in vertebrates (e.g. gills and tails)




4. Vestigial Structures5. Domestication (artificial selection)


4. Vestigial features I • Whales: hips and hind limbs are reduced to small bones with no function.

• In primitive snakes, the remnants of hind limbs persist (forelimbs are absent).

Vestigial features II

• The human appendix is a vestigial structure, reduced from the caecum of primate ancestors.






Von Holdt et al. (2010) Nature 464, 898-903







Pattern and process in evolution

Process

Inferenceabout

evolutionaryprocess

Inferenceabout

effect ontaxonomic

pattern

Pattern

Lecture 2


and

“Neo-Darwinism” or “The Modern Synthesis”

“Neo-Darwinism”or

“The Modern Synthesis”


“The Modern Synthesis”The same thing... but with better

understanding of how things work.




• Darwin’s Theory of Evolution by Natural Selection




• Darwin’s Theory of Evolution by Natural Selection• Mendel’s Laws of Heredity (1866, 1900; see SBS 008)




• Darwin’s Theory of Evolution by Natural Selection• Mendel’s Laws of Heredity (1866, 1900; see SBS 008)• Cytogenetics (1902, 1904 - )




• Darwin’s Theory of Evolution by Natural Selection• Mendel’s Laws of Heredity (1866, 1900; see SBS 008)• Cytogenetics (1902, 1904 - )• Population Genetics (1908; see Lectures 7-12)




• Darwin’s Theory of Evolution by Natural Selection• Mendel’s Laws of Heredity (1866, 1900; see SBS 008)• Cytogenetics (1902, 1904 - )• Population Genetics (1908; see Lectures 7-12) • Molecular genetics (1970s- ; see SBS 633/210 and Lecture 6)

Gregor Mendel (1822-1984)

Worked out the basic laws of inheritance:Segregation and independent assortment

J.B.S. Haldane (1892-1964)

With Fisher and Wright, one of the founders of population genetics.

“The Causes of Evolution” (1932): first major contribution to what became the “modern evolutionary synthesis".

R.A. Fisher (1890-1962)

Invented Analysis of Variance and other stats!

Worked on the theory of population genetics

Theodosius Dobzhansky (1900-1975)

“Nothing in Biology makes sense except in the light of

evolution”.

Theodosius Dobzhansky's Genetics and the Origin of Species, published in 1937.

Ernst Mayr (1904-2005)

Worked on speciation and the definition of species.





William D. Hamilton (1936 - 2000)

Explained how natural selection acts on social behaviour (“kin selection”)

Explained weird sex ratios

relatedness * benefit > cost

John Maynard-Smith (1920-2004)

Most widely known for applying game theory

to evolutionary biology

Summary/overview of Lecture 2

EVOLUTION(“descent with modification”)

Pattern Process

• Fossil record• Dating methods

• Molecular evolution• Molecular clocks

• Mechanisms• Environmental drivers

•climate•cont. drift•extinctions etc

The Modern Synthesis

What next?• Epigenetics

• Cultural transmission

• Niche construction

“Extended Evolutionary Synthesis” ?

• Comparative genomics

• Systems Biology“Postmodern Synthesis” ?

Pastafarianism - Church of the Flying Spaghetti Monster

Evolution lectures1&2 2012 slideshare

Education

species change

ideas inuenced darwin

species dont change

genus species

extinct species

early ideasfixity of

inuenced darwin wallace

charles lyell