Title: Phylogeny and Systematics
1Phylogeny 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.
2The 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
3The 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)
4Important Fossil Finds
- Australopithecus afarensis Lucy
www.wsu.edu
5Important 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
6The 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
7The 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)
8The 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
9The 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
10The 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
11The 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
12Mass Extinction
- Mass extinction followed by huge adaptive
radiations (many natural selections/huge
diversity of organisms)
13Systematics 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
14Systematics 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
15Systematics 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
16Systematics 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
17Convergent vs Divergent Evolution
- Analogous vs Homologous Adaptations
18Convergent 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
19Systematics 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
20Systematics 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
21Systematics 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
22Systematics 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
23AP 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