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Flashcards in Darwin Deck (28)
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What is Science?



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


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)


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


Natural Selection

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



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



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


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


Georges Cuvier

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


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


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


Georges Louis de Buffoon

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


Nicolaus Steno

o Younger rocks lie on top of older rocks


William Smith

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


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



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


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


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



linear growth


Darwin's old idea

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


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


Factors that Govern microevolution

new alleles
gene duplication
exon shuffling
horizontal gene transfer


new alleles

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


Gene duplication

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


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



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



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



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