Download Ch. 26 Phylogeny – PowerPoint Questions

Ch. 26 Phylogeny – PowerPoint Questions - KEY
Taxonomy
1. Who originally saw similarities between all living organisms and classified them? Linnaeus
a. What did he base his classification off of? Morphology (physical appearance)
b. What was the largest group he included in his classification system? (Note: Domain is
now the largest group, but it was not in the original system) Kingdom
i. What was the smallest? Species
2. What is taxonomy? The classification of organisms based on shared characteristics.
3. List the taxonomic groups from broad to narrow used today.
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Did King Phillip Come Over For Good Soup?
Phylogeny
4. What is phylogeny, and what are they based on? The study of the evolutionary relationships
among a group of organisms.
Phylogenies are based on
• Morphology and the fossil record
• Embryology
• DNA, RNA, and protein similarities
5. What is the difference between cladograms and phylogenetic trees?
A cladogram is used to represent a hypothesis about the evolutionary history of a group of
organisms.
A phylogenetic tree represents the “true” evolutionary history of the organism. Quite often
the length of the phylogenetic lineage and nodes correspond to the time of divergent events.
6. What type of evolution is seen at a node (branch point) on a phylogenetic tree? (The answer is
either convergent or divergent evolution) Divergent evolution
7. How can you tell how long ago something diverged in using a cladogram? The longer it’s line,
the further back in history it evolved
8. If a species is extinct, where will it be located on a cladogram? It WILL NOT be located up top
(all species up top are extant which means living)
9. Define polytomy – If more than two linages are shown, it indicates an unresolved pattern of
divergence or polytomy.
10. What are “sister taxa”? Sister taxa are groups or organisms that share an immediate common
ancestor.
11. How is a phylogenetic tree read differently when the branches are “flipped”? It isn’t. It still
shows the same evolutionary ancestry.
12. What is a clade? A clade is any taxon that consists of all the evolutionary descendants of a
common ancestor
13. What type of clade contains a common ancestor and all of its descendents? True clade
14. Compare and Contrast anagenesis and cladogenesis.
Compare:
Both represent the evolution of organisms.
Contrast:
Anagenesis shows when one population accumulates enough differences to where they are no
long considered the same species. (It is NOT the divergence of 1 species into 2. It is one
species continually changing over time and all of the members of that population showing
those changes due to adequate gene flow.)
Cladogenesis studies the budding of one or more new species from a species that continues to
exists. This would show divergent evolution.
15. The PowerPoint states that typically cladogenesis occurs when a parent population is
geographically divided, and the 2 subpopulations experience differential evolution. What is
another way in which cladogenesis can occur (BE SPECIFIC)?
Sympatric speciation: 1. Polyploidy, 2. Habitat Isolation, 3. Balanced Polymorphism, 4. Sexual
Selection
16. Explain how strata are formed, and how these can be used to determine the age of fossils.
17. Strata can determine the relative age of fossils. Explain a method that can be used that can
show the absolute age of a fossil.
Carbon dating using the half-life of carbon
18. Contrast ancestral traits and derived traits.
The original shared trait is termed the ancestral trait and the trait found in the newly evolved
organism being examined is termed the derived trait.
19. Contrast the reasoning behind by homologous structures and analogous structures exist.
Homologous structures show similarities due to shared ancestry (evolved together).
Analogous structures show similarities because of similar selection pressures (living in the
same kind of habitat, having similar niches).
Molecular Clock
20. What is meant by the term molecular clock?
The molecular clock hypothesis states: Among closely related species, a given gene usually
evolves at reasonably constant rate.
These mutation events can be used to predict times of evolutionary divergence.
Therefore, the protein encoded by the gene accumulates amino acid replacements at a
relatively constant rate.
21. Go to http://evolution.berkeley.edu/evosite/evo101/IIE1cMolecularclocks.shtml
a. Explain how a molecular clock works using the information found on this page.
We can determine the average rate at which mutations occur in DNA. We can then use
this information to determine how long ago 2 species diverged by looking at the
number of differences in their DNA.
22. Using molecular clocks mathematically (Use the “additional information” at the bottom of page
26 to help with this question).
a. Calculate the slope of this graph.
Slope = rise / run or (change in y) / (change in x)
= (0.9 – 0) / (500 – 0)
= 0.0018
b. What would the slope of the graph tell you? Average rate of change
c. Use the slope to then predict how many amino acids would change if 600 million years
had passed.
600 * 0.0018 = 1.08