Branching Out
(Phylogenetic Trees and Patterns of Life)
(Phylogenetic Trees and Patterns of Life)
Which mode of selection likely underlies the pattern of ‘splitting events’ when we look at the history of life on earth?
A. Balancing selection
B. Directional selection
C. Disruptive selection
D. Stabilizing selection
C. Disruptive selection
What occurs in a hybrid zone?
A. Extinction
B. Interbreeding
C. Fusion
D. Reinforcement
E. Disruptive selection
B. Interbreeding
What are the structural features all cells have?
plasma membrane, genetic material, ribosomes
Bacterium motility is often due to its possession of _____.
a. fimbriae
b. pili
c. a capsule
d. a flagellum
d. a flagellum
Stability is most likely to occur when _____.
A. postzygotic isolating mechanisms are in place
B. gene flow is low
C. hybrids have relatively the same fitness than either parent population
D. the environment is changing
C. hybrids have relatively the same fitness than either parent population
What major patterns of life can be observed across life's history?
1. character change
2. splitting events
3. stasis
4. extinctions
5. adaptive radiations
According to the _____, the main criterion for identifying species is reproductive isolation.
A. Biological species concept
B. Morphospecies concept
C. Phylogenetic species concept
D. Lamarkian species concept
E. Darwinian species concept
A. Biological species concept
In prokaryotes new mutations accumulate quickly in populations, while in eukaryotes new mutations accumulate much more slowly. The primary reasons for this are:
A. Prokaryotes have short generation times and large population sizes.
B. Prokaryotes have random mutations while eukaryotes can target genes for mutations; thus mutations may not accumulate as quickly in eukaryotes but they are more useful to the organism.
C. The DNA in prokaryotes is not as stable as eukaryotic DNA and is thus more likely to mutate.
D. Prokaryote mutations are less effective than eukaryote mutations in providing variation for evolution
A. Prokaryotes have short generation times and large population sizes.
Which of the following best describes all existing bacteria?
A. pathogenic, omnipresent, morphologically diverse
B. extremophiles, tiny, abundant
C. small, harmful, fast-growing
D. tiny, ubiquitous, metabolically diverse
E. morphologically diverse, metabolically diverse, extremophiles
D. tiny, ubiquitous, metabolically diverse
Approximately how far back in time does the fossil record extend?
a. 3.5 million years
b. 5.0 million years
c. 3.5 billion years
d. 5.0 billion years
c. 3.5 billion years
What is the principle of parsimony?
The scientific principle that things are usually connected or behave in the simplest or most economical way, especially with reference to alternative evolutionary pathways.
Which of the following is a weakness of the phylogenetic species concept?
A. It requires phylogenetic trees, which haven’t been estimated yet for many lineages.
B. It is not applicable to sexually reproducing species because the offspring are genetically distinct from the parents.
C. It isn’t applicable to asexual, fossil, or geographically isolated species.
E. It relies on the subjective judgment of experts to decide whether populations are similar enough to be the same
species
A. It requires phylogenetic trees, which haven’t been estimated yet for many lineages.
While examining a rock surface, you have discovered an interesting new organism. Which of the following criteria will allow you to classify the organism as belonging to Bacteria but not Archaea or Eukarya?
A. It is unicellular.
B. Cell walls are made primarily of peptidoglycan.
C. The organism does not have nucleus.
D. The lipids in its plasma membrane consist of glycerol bonded to straight-chain fatty acids.
E. It can survive at a temperature over 100°C.
B. Cell walls are made primarily of peptidoglycan.
Microbiologists use the Gram stain to aid in the identification of bacteria. What is the major difference between
Gram-positive and Gram-negative bacteria?
A) structure of nucleotides in the plasma membrane
B) presence or absence of muramic acid in the cell wall
C) presence or absence of peptidoglycan in the cell wall
D) presence or absence of outer plasma membrane
C) presence or absence of peptidoglycan in the cell wall
What kind of methods are there for prokaryotes to obtain energy (ATP)? How do prokaryotes obtain carbon?
ATP:
1. phototrophs - light
2. chemotrophs - organic and inorganic materials
Carbon:
1. autotrophs - make C-C bonds from inorganic sources
2. heterotrophs - consume/obtain C-C bonds from organics from other organisms
Put the following events from the history of life in relative order (1 = earliest, 5 = most recent)(1pt)
____Origin of prokaryotes
____Origin of animal life
____Origin of eukaryotes
____Origin of multicellularity
1 Origin of prokaryotes
4 Origin of animal life
2 Origin of eukaryotes
3 Origin of multicellularity
List all three species concepts and the criteria needed to define a species for each concept.
Morphological: characterizes a species by body shape and other structural features
Biological: Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations.
Phylogenetic: defines a species as the smallest monophyletic group on a phylogenetic tree
If prokaryotes reproduce asexually through binary fission, and the resulting daughter cells are genetically
identical, where does the genetic variation necessary for evolution come from? (2pt)
Mutation, gene duplication, gene flow/genetic recombination (transduction, transformation, conjunction)
What are the forms of genetic recombination that prokaryotes do?
1. transduction: movement of genes between bacteria by bacteriophages
2. transformation: A change in genotype and phenotype due to the assimilation of external DNA by a cell.
3. conjugation: In bacteria, the direct transfer of DNA between two cells that are temporarily joined via a pili
What are the themes in diversity of prokaryotes?
1. morphological
2. genetic recombination/mutation
3. METABOLIC DIVERSITY
Make a phylogenetic tree with 5 species (A, B, C, D, and E) A and D are sister taxa. B and E are sister taxa. C is the next closest relative to A, D, B, and E. What is the outgroup? What would you circle/include to identify a monophyletic group of 4 species?
C is the outgroup.
Circle A, D, B, and E and the node of their common ancestor.
List all three species concepts and their corresponding limitations.
Morphological:
1. subjective criteria
2. cannot identify cryptic species
3. polymorphic species
Biological:
1. cannot apply to fossils
2. only sexually reproduction
3. need geographic overlap
4. not always black and white (ex. polar and grizzly)
Phylogenetic:
1. not too much data on phylogenetic trees (is increasing so not as much of a limitation)
2. can create a larger number of species that would otherwise be indistinguishable
Compare and contrast members of Eukaryotes with Prokaryotes (2pts)
Eukaryotes have a nucleus, while prokaryotes do not. Eukaryotes have multiple linear chromosomes, while prokaryotes have one circular chromosome. All prokaryotes are unicellular, while Eukaryotes can be both unicellular or multicellular. Both eukaryotes and prokaryotes have ribosomes, a plasma membrane, and genetic material.
Compare and contrast members of Domain Archaea with Domain Bacteria. (2pts)
Archaea can grow in temperature above 100 degrees Celsius, while bacteria cannot. Archaea are more similar to Eukarya when it comes to proteins involved in protein synthesis.
Both have prokaryotic morphology: no nucleus, one circular chromosome
What are the four reasons why prokaryotes are important? BONUS: can you list examples and how to identify them?
1. ecosystem function: Cyanobacteria (photosynthesis, 75% of Earth's O2)
2. symbiont: Firmicutes (Metabolism in human gut, firm="strong"; cuti="skin," gram-positive)
3. Biomedical: Actinobacteria (used to produce antibiotics, gram-positive)
4. Research: Proteobacteria (used in biotechnology, example: E. coli used for gene cloning)