Biological Evolution Exam 3
- 1.What two factors determine the phenotypic variation we see in populations? (mark both)
- A.
Variation in number of chromosomes
- B.
Variation in the rate of mutation for neutral haplotypes
- C.
Genetic (allelic) variation
- D.
Life span variety across multiple ecological niches
- E.
Environmental variation
- 2.Which of the following species definitions would make use of a phenotype space to draw the boundaries between species?
- A.
Morphological species concept
- B.
Phylogenetic species concept
- C.
Retrograde species concept
- D.
Biological species concept
- 3.Which of the following events might help a population that was stuck on a suboptimal adaptive peak move to another peak in a very rugged adaptive landscape?
- A.
A switch in the ratio of males to females.
- B.
Increasing the adaptive benefit of traits already found in the population.
- C.
A dramatic reduction in population size (bottleneck event).
- D.
A chromosomal fusion so that chromosome count is reduced.
- 4.The following species have not yet had their genome size estimated. Based on your understanding of the C-value paradox, which would be the most likely to have the largest genome?
- A.
Panellus stipticus, a fungus
- B.
Anaitides erythrophyllus, a polychaete worm
- C.
Felis concolor, a mountain lion
- D.
Tramea onusta, a dragonfly
- E.
None of the above, the c-value paradox means you cannot predict genome size of eukaryotes
- 5.Recombination of eukaryotic genomes is very common and happens equally across all regions of the genome.
- A.
True
- B.
False
- 6.What do viral genomes look like compared to those of living organisms?
- A.
They are arranged in multiple pieces instead of being in on large string of DNA.
- B.
They are interspersed with large sections of non-coding DNA.
- C.
Their genetic code is completely different than the genetic code of living organisms.
- D.
They are typically smaller than the genomes of living organisms, although there is some overlap in genome size with the bacteria and archaea.
- 7.The history of which group of organisms has been most impacted by horizontal gene transfer via plasmids?
- A.
Bacteria
- B.
Plants
- C.
Fungi
- D.
Animals
- 8.I examine all of the DNA sequence that translate into the amino acid proline and notice the following distribution: 10% CCA15% CCC12% CCT63% CCG This is a clear example of ____________________.
- A.
GC content bias
- B.
Genetic drift
- C.
Artificial selection
- D.
An isochore
- E.
Codon usage bias
- 9.What is the most likely cause of the pattern seen in the problem above?
- A.
Selection for increased translational efficiency
- B.
A bottleneck effect
- C.
Neutral mutations fixed by genetic drift
- D.
A long period of asexual reproduction
- 10.Which of the following might help us to identify a recent horizontal gene transfer?
- A.
A bacterial genome with a uniform GC content bias
- B.
A bacterial genome without any isochores
- C.
A bacterial genome with a small region that has a GC content bias different than the rest of the genome
- D.
A bacterial genome with more than five types of membrane proteins
- 11.Why is there such a strong correlation between genome size and gene number among the prokaryotes?
- A.
Because the prokaryotes don't undergo mitosis.
- B.
Because the prokaryotes have no multicellular individuals.
- C.
Because there is little non-coding DNA in prokaryotes genomes.
- D.
Because prokaryotes are heterotrophs.
- 12.In natural populations the census population (N) size is always larger than the effective population size (Ne).
- A.
True
- B.
False
- 13.I estimate the effective population size for a group of badgers, but when I measure there Heterozygosity levels I notice they are much lower than they should be. Assuming my estimates of effective population size and measurements of Heterozygosity are accurate what is the most likely explanation for this discrepancy?
- A.
The population must have gone through a recent bottleneck event.
- B.
There has been strong natural selection that has caused fixation of nearly every gene.
- C.
There must have been little to no new mutations over the last several thousand years.
- D.
Lateral Gene transfer from distantly related mammals.
- 14.Why is the mitochondrial gene diversity of the most northerly population of black spruces so much lower than the nuclear gene diversity of the same populations
- A.
These populations are subjected to a much more extreme environment and so there has been strong selection for nuclear gene diversity, which increases their ability to adapt.
- B.
The mitochondrial genome is only inherited from the maternal lineage and since seeds don’t travel very far in this species these populations only represent the diversity of a small number of individuals that were at the glacial margin when the last ice age ended.
- C.
Horizontal gene transfer events have eliminated the transposons that normally generate much of the mitochondrial gene diversity.
- D.
Large herbivores have selectively grazed the seedling of individuals with low toxicity. Since this trait is mainly encoded on the mitochondrial genome this has greatly reduced this diversity.
- 15.In very large populations genetic drift has only a small effect on evolution.
- A.
True
- B.
False
- 16.Which of the following is not a reason why we would expect most evolution to be effectively neutral?
- A.
Chromosome rearrangement is frequent for all taxonomic groups
- B.
Lots of non-coding DNA in eukaryotes
- C.
Many mutations have little or no phenotypic impact even if they change the protein sequence
- D.
Degeneracy of the DNA code
- E.
Mutations that have a measurable phenotypic impact may still not have any effect on the fitness of an organisms
- 17.Which value predicts the rate of fixation for neutral mutations in populations?
- A.
Ne, the effective populations size
- B.
µ, the mutation rate
- C.
Γ, the interspecies immigration rate
- D.
S, the average selection coefficient
- 18.What are two issues that can complicate molecular clock estimations?
- A.
Variation in mutation rates between different lineages
- B.
The number of chromosomes in different eukaryotic organisms
- C.
The amount of non-coding DNA in different lineages
- D.
If the genetic data is approaching saturation
- 19.Homeotic transformations require the coordinated action of multiple changes in both the regulation and coding sequence of different toolkit genes.
- A.
True
- B.
False
- 20.Vertebrate embryos from distantly related lineages show a marked similarity to one another at the early stages of embryogenesis and often exhibit ancestral features that are absent, or highly modified in the adult form. This statement best describes which of the following phrases?
- A.
Meiotic drive emulates embryogenesis
- B.
Preformation generates morphological complexity
- C.
Ontogeny recapitulates phylogeny
- D.
Neurogenesis portends gastrulation
- 21.An early embryonic cell that has the potential to differentiate into any cell in the developing embryo is referred to as ___________________.
- A.
Semipotent
- B.
Pluripotent
- C.
Fully endowed
- D.
Omnicapable
- 22.Which of the following is a pronounced example of the power of heterochrony to effect drastic morphological change of the adult form?
- A.
The difference between Homo erectus and Praeanthropus afarensis.
- B.
Paedomorphism via neoteny in the axolotl (Mexican salamander).
- C.
Aggregation of individual amoeba like cells into a reproductive “slug” in the slime molds.
- D.
The equal number of individuals from either sex in the populations of most eukaryotes.
- 23.Which of the following is not a characteristic of Hox genes?
- A.
They are present in all metazoans (animals).
- B.
They are found in a colinear arrangement in the genome.
- C.
They are transcription factors that control the patterning of different body regions.
- D.
They code for an ancillary form of ribosomes that are only active during embryogenesis.
- 24.Species boundaries cannot always be objectively drawn, even when the populations in question are sexually reproducing.
- A.
True
- B.
False
- 25.Grouping populations into species based on their ability to share genetic material between populations. This is an example of application of the _______________ species concept.
- A.
Morphological
- B.
Biological
- C.
Phylogenetic
- D.
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