The discovery of the past Georges Cuvier Charles Lyell To study evolution means to dig in the past. The science of past organims is paleontology (greek: palaews: old, logos: science) Paleontology deal with fossils (lat. fodere = to dig) Early paleontology mainly described ancient life within the Linnean framework Modern paleontology tries to reconstruct ancient life. It links therefore ecology and taxonomy. Mary Anning (1799- 1847) Richard Owen (1804- 1892)
The discovery of the past. To study evolution means to dig in the past. The science of past organims is paleontology ( greek : palaews : old, logos : science) Paleontology deal with fossils (lat. fodere = to dig). Charles Lyell. Georges Cuvier. - PowerPoint PPT Presentation
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The discovery of the past
Georges Cuvier
Charles Lyell
To study evolution means to dig in the past.
The science of past organims is paleontology (greek: palaews:
old, logos: science)
Paleontology deal with fossils (lat. fodere = to dig)
Early paleontology mainly described ancient life within the Linnean framework
Modern paleontology tries to reconstruct ancient life.
The evolutionary change within a lineage is called anagenesis
The diversification of an evolutionary tree is called cladogenesis
Linnean systematics and cladistics
Linnean approach
Hierachical encaptive system
Phenomenological method based on similarity
It uses grades (groups of similar body plan)
Different taxonomies are possible
There is no clear decision intrument for taxonomies
The number of higher taxa is rather small (Pisces, Amphibia, Reptilia, Aves, Mammalia)
It does not assume common evolutionary history
It does not reconstruct evolution
Taxonomy is independent of evolution
Hennigean approach
Hierachical encaptive system
Analytical method based on lineage branching
It uses clades (groups of identical root)
Only one taxonomic solution is allowed
Autapomorphies decide about taxonomic position
The number of higher taxa is large (Pisces, Amphibia, Reptilia are not valid taxa )
It is based on common evolutionary history
It does reconstruct evolution
Taxonomy is a part of evolutionary theory
Low resolution trees High resolution trees
The principle of maximum parsimony (Occam’s razor) holds that we should accept that phylogenetic tree that can be constructed with the least number of morphological
changes.
The construction of phylogenetic trees from numerical methods
Characters (or transitions) have to be independent.
Impossible character states have to be excluded.
Scales
Hairs
Feathers
Loss of feathersLoss of hairsFish
MammalsBirds
Incompatible
Characters are assumed to have equal importance. In reality transitions are not comparable.
To overcome this problem you give character weights. Technically you multiply the occurrence of a character in a distance matrix
A B C1 C2 DA 1 0 1 1 6B 1 2 4 4 2C1 4 5 2 2 1C2 4 5 2 2 1D 1 0 3 3 2
Species SequenceA A A T T A A C C C A A T AB C A T T A A C C C A A T AC C G T T T G G A A T G A CD C G T G T G G A A T A A AE G G T G T G C C C A A T A
Trees from molecular data
A B C D EA 0 1 11 10 5B 1 0 10 9 5C 11 10 0 3 9D 10 9 3 0 6E 5 5 9 6 0
Distance matrix
Linus Pauling (1901-1994)
Motoo Kimura(1924-1994)
Emile Zuckerkandl(1922-2013)
Evolutionary time scalesThe molecular clock
Numbers of amino acid substitutions and therefore trespective numbers of nucleotide substitutions are for many proteins and genomes approximately
proportional to time.
Hence, numbers of substitutions are a measure of time of divergence from
the latest common ancestor.
Substitutions alone provide a relative time scale
An appropriate calibration adds the absolute time scale
Darwin’s first principle: All species of a given taxon have a common ancestor.
Parsimony analysis cannot answer this question. A brush would always have a lower number of character changes
TimeSpontaneous origin of simple life forms
Sca
le o
f or
gani
zatio
n
Scala naturae
A brush means:
• No speciation.
• If we except that extinction occurs this would mean a constant decrease in the number of species.
• Character change within whole species.
• No genetic (character) variability within populations.
• Extreme longevity of lineages.
Theory of Lamarck
But horizontal gene transfer and might at least in bacteria result in networks and rings!
History of palaeontology: http://en.wikipedia.org/wiki/History_of_paleontologyHistory of earth: http://wiki.cotch.net/index.php/History_of_the_EarthRadiometric dating details: http://www.tulane.edu/~sanelson/eens211/radiometric_dating.htmGeological time scale: http://en.wikipedia.org/wiki/Geologic_time_scale
Ernst Haeckel: Kunstformen der Natur (Internet exhibition of original drawings: http://caliban.mpiz-koeln.mpg.de/~stueber/haeckel/kunstformen/liste.html
The modern molecular clock: http://awcmee.massey.ac.nz/people/dpenny/pdf/BromhamPenny_2003.pdf