Evolution Flashcards
(45 cards)
What is virus evolution?
The constant change of a viral population in the face of selection pressures
What are quasispecies?
Viral populations that exist as dynamic distributions of nonidentical but related replicons
What is lethal metagenesis?
The elevation of mutation rates by exposure to a mutagen or an error-prone polymerase to the point at which resulting population of genomes has lost fitness and is incapable of propagating
What is an error threshold?
A mathematical parameter that measures the complexity of the information that must be maintained to ensure survival of a population
What is genetic bottleneck?
A descriptive terms evoking the extreme selective pressure on small populations that results in loss of diversity; accumulation of selected mutations; or both
What is Muller’s Ratchet?
A model positing how small asexual populations decline in fitness over time if the mutation rate is high
Mutations are acquired, never removed: Rachet “clicking” relentlessly in one direction
If too many mutations occur, fitness decreases
What is genetic drift?
Diversity in viral genomes that arises as a result of errors during genome replication and immune selection
What is genetic shift?
Diversity in viral genomes that arises as a result of re-assortment of genome segments or recombination between genomes
What is a root in a phylogenetic tree?
common ancestor of ALL organisms in tree
What is a node in a phylogenetic tree?
aka internal node
Common ancestor of species; diversification of species
What are tips in a phylogenetic tree?
aka terminal nodes
current organsism
What is a sister taxa in a phylogenetic tree?
organisms that come from the same common ancestor
What is a branch in a phylogenetic tree?
the part of an evolutionary tree that connects nodes
Is the best way to read an evolutionary tree is across the tips (terminal nodes)?
NO because nodes can be rotated
In a cladogram, what matters?
Topology (branching order)
In a phylogram, what matters?
Topology and branch length
What is an easy way to find the number of clades?
Count the number of nodes
What type of influenza virus strain has the greatest capacity to cause pandemics?
Type A because they have a higher mutation rate
Small incremental increases in genetic change over type would be the result of _________
Genetic drift
Rapid increases in genetic change over time would be ________
Genetic shift
Is genetic drift analogous to natural selection?
No it is not because genetic drift is random, natural selection is survival of the fittest
What are some representations of genetic drift?
Bottleneck effect
Founder effect
What scientific discipline is Paleovirology primarily built on?
Genetics/genomics
The identification of giant viruses contributes to what type of origin of viruses theory?
Regressive model
