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Flashcards in Darwin Deck (28)
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1

What is Science?

CONCLUSIONS ARE TENTATIVE

2

Doushantuo fossils

Cambrian explosion

• For a long period of time, what was concluded was that the fossils showed the first sign of eukaryotic life: CLASSICAL VIEW
• January 2007: was discovered that the fossils WERE NOT ANIMALS, but instead sulphur-oxidizing bacteria
• April 2007: Doushanyuo organisms were indeed eukaryotic and were most probably early cleavage stage embryos
• December 23 2011: Concluded that the fossils were neither animals nor embryos and preclude post cleavage embryology characteristic of metazoans
• 2014: intermediate and primitive to both

3

Charles Darwin

pursued being a naturalist
• In Galapagos, Darwin observed that species were similar to species on the mainland of South America, and that species varied from island to island
• Postulated that species had reached the islands from the mainland, but then had undergone different changes on different islands (NATURAL SELECTION)

4

Natural Selection vs Evolution

• Natural selection works on the phenotypes of the individuals
o Is the process that leads to evolution
o Beaks of the birds of the galapagos
• Evolution is the change from one generation to the next in the ACTUAL GENE POOL OF THE POPULATION

5

Natural Selection

is a process in which individuals with favorable inherited traits are more likely to survive and reproduce

6

Macroevolution

• Major evolutionary change
• Evolution of whole taxonomic group over long periods of time
how different species come about

7

microevolution

• Evolutionary change within a species or small groups of organisms
change in the gene pool

8

Carolus Linnaeus

• Binomial nomenclature and taxonomy
• Described over 100,000 different species
o Began to categorize and put them in different groups
• Did not believe in evolution
• Believed that the diversity of life was a divine creation with NO EXCTINCTION
Linnaeus ascribed the resemblance among species to the pattern of creation rather than evolution

9

Georges Cuvier

Catastrophism
• Did not believe in evolution
• Catastrophism
o Organisms are destroyed and new ones are put on earth

10

Lyell and Hutton

changes in Earth;s surgace can result from slow, continuous actions still operating today
• Lyell further proposed that the mechanisms of change are constant over time

11

Archbishop Ussher

o Creation occurred on the evening of Sunday, October 23, 4004 B.C
o Earth was only 6000 years old
o Was printed until the beginning of the 20th century

12

Georges Louis de Buffoon

o Earth was 70,000 years
o Life changes over time

13

Nicolaus Steno

o Younger rocks lie on top of older rocks

14

William Smith

o Produced the first detailed geological map
o Each formation contained a distinctive assemblage of fossils

15

James Hutton

o Founder of modern geology
o Earth was millions of years old
o Sediments form by slow accumulation of particles sinking to bottom of oceans and lakes

16

Lyell

o Uniformitarianism
• Slow forces that shaped the Earth are still operating today

17

Jean Baptiste Lamarck

Inheritance of Acquired CHaracteristics
extinction did not exist, but instead species continually evolved into living forms.
• Ancestor of the present day giraffe acquired a longer neck through the process of stretching its neck to feed on the leaves of trees
• Over time, stretching led to the evolution of the long necked giraffe
• WRONG

18

Alfred Russell Wallace

• Proposed a theory of evolution due to natural selection
• The potential for human population to increase faster than food supplies and other resources
• If some heritable traits are advantageous, these will accumulate in a population over time, and this will increase the frequency of individuals with these traits
• Process explains the match between organisms and their environment

19

Malthus

linear growth

20

Darwin's old idea

species were idealized types, fixed elements in a clearly defined natural order

21

Darwin's Five Facts and Three Intereferences

• Fact 1: All species have great potential fertility
• Fact 2: Populations normally display stability
• Fact 3: In a stable environment resources are limited and remain relatively constant
o Interference 1: there must be a fierce struggle for existence
• Fact 4: Populations display enormous variability
• Fact 5: Much of this variation is heritable
o Interference 2: Survival is not random, this unequal survival is the process of NATURAL SELECTION
o Interference 3: Over generations this process of natural selection will lead to a continuing gradual change of populations, that is EVOLUTION

22

Factors that Govern microevolution

new alleles
gene duplication
exon shuffling
horizontal gene transfer

23

new alleles

o Random mutations within pre-existing genes introduce new alleles into populations, but at a very low rate

24

Gene duplication

o Abnormal crossover events and transposable elements may increase the number of copies of a gene

25

exon shuffling

o Abnormal crossover events and transposable elements may promote gene rearrangements in which one or more exons from one gene are inserted into another gene

26

hetermoetry

difference in the amount of a gene product that is produced
finches: bills

27

heterchrony

difference in the timing of gene expression during development (onset, offset and duration – Giraffe’s neck)

28

heterotopy

difference in the spatial pattern of gene expression during development (BMP4 expression in bird feet)