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Phylogeny and Systematics

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Title: Phylogeny and Systematics


1
Phylogeny and Systematics
  • Chapter 25
  • When biologists study macroevolution, they
    consider the major events revealed by the fossil
    record large diversifications of taxonomic
    groups, the origin of novel biological designs,
    and major extinctions. Phylogeny is the
    evolutionary history of a species. The study of
    the diversity of life and its phylogenetic
    history is called systematics.

2
The Fossil Record and Geologic Time
  • Phylogeny the evolutionary history of a species
    or group of related species
  • Remember ontogeny recapitulates phylogeny
  • Systematics study of the biological diversity
    in an evolutionary context
  • Fossil record sequence in which fossils appear
    in the layers of sedimentary rock studied by
    paleontologists

http//www.mun.ca/biology/scarr/Phylogeny_of_Repti
les2.gif
3
The Fossil Record and Geologic Time
  • Sedimentary rock formed from layers of minerals
    settling out of the water
  • Dead organisms settle along with the sediments
    and are compacted and sometimes preserved as
    fossils
  • Some fossils are impressions the organisms made
    in sediment before they decayed and disappeared
  • The fossil record is incomplete because it favors
    organisms that existed for a very long time, were
    relatively widespread, and had shells or hard
    bony skeletons

http//www.students.k.csbsju.edu/krarntson/formati
on_sedimentary1.jpg
(only 1 of organism fossilized)
4
Important Fossil Finds
  • Australopithecus afarensis Lucy

www.wsu.edu
5
Important Fossil Finds
  • Coevoltuion organisms that evolved
    simultaneously
  • Evidence both from behavior, fossils, and genetics

http//www.wildlifehc.org/ewebeditpro/items/O57F12
76.gif
http//www.middle-fork.org/archives/dUnkBeelikeIns
ect.gif
6
The Fossil Record and Geologic Time
  • Relative dating fossils in each layer of rock
    represent certain time periods, the layers nearer
    the top representing more recent time periods
  • Index fossils those found in more than one
    location that can be used to correlate
    information about the strata in both locations

http//pubs.usgs.gov/gip/geotime/fossils.gif
7
The Fossil Record and Geologic Time
  • Geologic time scale shows a consistent sequence
    of periods and events in the history of the earth
  • Four eras
  • Precambrian
  • Paleozoic
  • Mesozoic
  • Cenozoic
  • (end of each era signifies an extinction)

8
The Fossil Record and Geologic Time
  • Absolute dating refer to a fossils age given
    in years rather than in reference to one another
  • Radiometric dating measuring the level of
    certain radioactive isotopes in fossils or rocks
    to determine their ages

http//www.bible.ca/tracks/dating-radiometric-cart
oon.gif
9
The Fossil Record and Geologic Time
  • Half-life the length of time it takes for 50
    of the original isotope sample to decay
  • Paleontologists measure the amount of an isotope
    in a rock or fossil and then knowing the
    isotopes half-life use that measurement to
    determine the approximate age of the rock

http//www.winona.msus.edu/Geology/MRW/mrwimages/E
arth20History/dating_ig_rx.jpg
10
The Fossil Record and Geologic Time
  • Continents plates of the earths crust that
    float slowly on the liquid mantle of the earth
  • Pangaea about 250 million years ago all major
    land masses were joined in this supercontinent
  • The supercontinent broke up about 180 million
    years ago causing extensive geographic isolation

http//www.meckcom.net/ssutphin/pangaea.jpg
11
The Fossil Record and Geologic Time
  • Extinction can occur because the habitat of a
    species is destroyed or because the environment
    has changed to make existence impossible
  • There have been two major extinctions in earths
    history
  • Permian extinction
  • Cretaceous extinction

http//www.geo.utexas.edu/courses/303/0701_mass_ex
tinctions.jpg
12
Mass Extinction
  • Mass extinction followed by huge adaptive
    radiations (many natural selections/huge
    diversity of organisms)

13
Systematics Connecting Classification to
Phylogeny
  • Systematics - study of biological diversity in
    the context of evolution, and it includes
    taxonomy, which is the naming and classification
    of species and groups of species

http//sonne.prz.tu-berlin.de/yomag/upload/11/1/63
19_1_biodiversity-2-large.jpg
14
Systematics Connecting Classification to
Phylogeny
  • Binomial used to describe species consisting of
    the genus and the species within the genus
  • The heirarchical classification of organisms
    consists of the following levels in order of
    increasing broadness species, genus, family,
    order, class, phyla, kingdom, domain

15
Systematics Connecting Classification to
Phylogeny
  • Phylogenetic trees show the heirarchical
    classification of taxonomic levels for organisms
  • Cladogram relational diagrams based on
    phylogeny, each branch is called a clade and the
    sequence of branches is based on homology
  • The greater the homology between two organisms
    the more closely related they are evolutionarily
    through common ancestry

http//www.calacademy.org/research/izg/CLADOGRAMS
20FOR20WEB/cladogram20Animals.jpg
16
Systematics Connecting Classification to
Phylogeny
  • Convergent evolution takes place when two
    organisms became alike because they adapted to
    similar environmental challenges, not because
    they have evolved form a common ancestor, this is
    known as analogy

http//www.pbs.org/wgbh/evolution/library/01/4/ima
ges/l_014_01_l.jpg
17
Convergent vs Divergent Evolution
  • Analogous vs Homologous Adaptations

18
Convergent vs Divergent Evolution
  • Homologous Adaptations
  • Cladogram
  • Similarities explained through shared ancestry
  • Analogous adaptations
  • No cladogram for trait
  • Similarities explained through similar
    environments, natural selection occurred
    separately and similarity

19
Systematics Connecting Classification to
Phylogeny
  • Molecular systematics the comparison of genes
    and proteins of different organisms allows us to
    determine evolutionary relationships on a
    molecular level
  • The more alike the DNA sequences of two organisms
    are, the more closely related they are
    evolutionarily

http//www.zin.ru/labs/img/molsyst_01.jpg
20
Systematics Connecting Classification to
Phylogeny
  • The rate of evolution of DNA sequences varies
    from one part of the genome to another, so
    comparing these different sequences helps us to
    investigate relationships between groups of
    organisms that diverged a long time ago

http//www.life.umd.edu/classroom/biol106h/Lec8/5p
roteins.jpg
21
Systematics Connecting Classification to
Phylogeny
  • Parsimony principle that dictates that theories
    should be kept as simple as possible while still
    being consistent with the evidence
  • This way of thinking is used to create phylogenies

http//www.fiu.edu/biology/pcb4674/ch14/PARSIMONY
.JPEG
22
Systematics Connecting Classification to
Phylogeny
  • Parsimony can be applied to the creation of
    phylogenetic trees because in evolution heredity
    fidelity is more common than change - in other
    words, phylogenetic trees are hypothetical
  • Molecular clocks methods used to place the
    origin of taxonomic groups more precisely in time

http//upload.wikimedia.org/wikipedia/en/e/e7/Phyl
ogeneticTree.jpg
23
AP Themes
  • Science as a process new evidence has created
    the 3 domain system instead of five kingdoms
  • Continuity and Change- all species tend to
    maintain themselves from generation to generation
    (pass on your genes) but some change occurs in
    DNA over time
  • Structure and Function homologous digits have
    different functions now in descendents
  • Interdependence on nature we are dependent on
    environment, including what adaptations our
    species develops
  • Evolution explains our diverse species
  • Science, Technology, and Society Current
    research is locating genes for traits and our
    phylogenetic tree
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