Transcript Ch 25

Students
-LL Ch 22 – 24: Due Monday
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Chapter 25 Essential Questions
LO 1.13 The student is able to construct and/or justify mathematical
models, diagrams or simulations that represent processes of
biological evolution.
LO 1.17 The student is able to pose scientific questions about a group of
organisms whose relatedness is described by a phylogenetic tree
or cladogram in order to (1) identify shared characteristics,
(2) make inferences about the evolutionary history of the group,
and (3) identify character data that could extend or improve the
phylogenetic tree.
LO 1.18 The student is able to evaluate evidence provided by a data set
in conjunction with a phylogenetic tree or a simple cladogram to
determine evolutionary history and speciation.
LO 1.19 The student is able create a phylogenetic tree or simple
cladogram that correctly represents evolutionary history and
speciation from a provided data set.
LO 1.26 The student is able to evaluate given data sets that illustrate
evolution as an ongoing process.
Chapter 25: Phylogeny & Systematics
1. What is phylogeny?
- Evolutionary history of a species
2. How can we trace phylogeny?
- Relative dating
- Based on layer fossil is found in
- Older or younger
- Absolute dating – p 517
- Radiometric dating – C14, U238
- Years ago alive
- Example:
- How long ago was fossilized organism alive?
- Given: 1/16 isotope remaining & isotope has t½ = 4000 yrs
- Answer
- 1/16 = 4 half lives
- 4 X 4000 yrs = 16,000 yrs ago it was alive
Figure 25.4 A gallery of fossil types
(c) Leaf fossil, about 40 million years old
(b) Petrified tree in Arizona, about
190 million years old
(a) Dinosaur bones being excavated
from sandstone
(d) Casts of ammonites,
about 375 million
years old
(f) Insects
preserved
whole in
amber
(g) Tusks of a 23,000-year-old mammoth,
frozen whole in Siberian ice
(e) Boy standing in a 150-million-year-old
dinosaur track in Colorado
Chapter 25: Phylogeny & Systematics
1. What is phylogeny?
2. How can we trace phylogeny?
3. Why aren’t there more fossils for “missing links” to extant organisms?
- Conditions must be perfect for fossilization & discovery
- May be present but not found
4. What is the difference between convergent & divergent evolution?
- Convergent
- Species from different evolutionary branches develop structures that
resemble one another
- Shows analogy between species…..not homology from a
common ancestor
- Divergent – gradual changes over time
5. What is taxonomy?
- Identification & classification of species
- DKPCOFGS
Figure 25.8 Hierarchical classification
Species
Panthera
Genus
Felidae
Family
Carnivora
Order
Class
Phylum
Kingdom
Domain
Panthera
pardus
Mammalia
Chordata
Animalia
Eukarya
Chapter 25: Phylogeny & Systematics
1. What is phylogeny?
2. How can we trace phylogeny?
3. Why aren’t there more fossils for “missing links” to extant organisms?
- Conditions must be perfect for fossilization & discovery
- May be present but not found
4. What is the difference between convergent & divergent evolution?
- Convergent
- Species from different evolutionary branches develop structures that
resemble one another
- Shows analogy between species…..not homology from a
common ancestor
- Divergent – gradual changes over time
5. What is taxonomy?
- Identification & classification of species
- DKPCOFGS
6. What is a cladogram?
- Diagram that shows shared characteristics
Figure 25.11 Constructing a cladogram
Chapter 25: Phylogeny & Systematics
1. What is phylogeny?
2. How can we trace phylogeny?
3. Why aren’t there more fossils for “missing links” to extant organisms?
- Conditions must be perfect for fossilization & discovery
- May be present but not found
4. What is the difference between convergent & divergent evolution?
- Convergent
- Species from different evolutionary branches develop structures that
resemble one another
- Shows analogy between species…..not homology from a
common ancestor
- Divergent – gradual changes over time
5. What is taxonomy?
- Identification & classification of species
- DKPCOFGS
6. What is a cladogram?
- Diagram that shows shared characteristics
- Groups can either be monophyletic, paraphyletic or polyphyletic
Monophyletic – one group coming from a single common ancestor
Paraphyletic – a grouping with one but not all ancestors derived from it
Polyphyletic – a grouping of several species that lack a common ancestor
Chapter 25: Phylogeny & Systematics
1. What is phylogeny?
2. How can we trace phylogeny?
3. Why aren’t there more fossils for “missing links” to extant organisms?
- Conditions must be perfect for fossilization & discovery
- May be present but not found
4. What is the difference between convergent & divergent evolution?
5. What is taxonomy?
6. What is a cladogram?
7. How can molecular clocks help to track evolutionary time?
- Assumes that some genes & parts of the genome appear to evolve
at a constant rate
- We can then compare genomic changes to known evolutionary
branch points in the fossil record
- Using a molecular clock, researchers concluded that HIV-M first infected
humans in the 1930s
8. How have all organisms descended from a common ancestor on
the universal tree of life?
Figure 25.18 The universal tree of life
Bacteria
Eukarya Archaea
0
4 Symbiosis of
chloroplast ancestor
with ancestor of
green plants
Billion years ago
1
3 Symbiosis of
mitochondrial
ancestor with
ancestor of
eukaryotes
4
2
3
2 Possible fusion of
bacterium and
archaean, yielding
ancestor of
eukaryotic cells
2
3
1
4
Origin of life
1 Last common
ancestor of all
living things
Many phylogentic relationships have been shown through molecular biology
- DNA sequencing
- protein sequencing