Selection & Speciation Flashcards
These are causes of microevolution, which change allelic frequencies.
Environmental pressures
The source of all variation?
MUTATION
Non-hertiable mutations?
Somatic
Heritable mutations?
Gametic
Two types of mutations (Spidermans)
Spontaneous - replication errors
Induced - radioactive spider bite. Mutagenic agents.
The change of a base pair?
Point mutation
A change to DNA with no effects.
Silent mutation
A change to DNA that changes the amino acid?
Missense mutation
Premature stop, effects can be nothing to everything!
Nonsense mutation
Sickle cell anemia is a..
Missense mutation
T/F Reading frames can be restored through 3 deletions.
TRUE
T/F Deletions & Insertions can be spontaneous or induced.
TRUE
Deletions:
Change amino acid sequence
Insertions:
Adding extra, making stop sequence
A deletion could be restored by…
Insertion
A random event that changes allelic frequencies?
Genetic Drift (Change to population)
Genetic Drift effects larger or smaller populations more?
Saller
Examples of genetic drift?
Picking all the flowers
Removing a large portion of a group at random (tsunami, hunting)
Bottleneck Effect
The isolation and colonization of a subpopulation.
Founder Effect
An example of the founder effect?
Shar-Peis - resulting in prevalent genetic disorders
Most populations are not closed systems, with immigration (to) and emigration (from). This movement creates:
Gene Flow
Gene flow does 2 things:
Reduce differences between populations
Amalgamation of populations
Darwinian fitness is NOT ALWAYS:
Physical Strength
The most successful is determined by:
Reproductive Success
In mammals, the right to reproduce can lead to
Male-Male competition
(Singing, dancing, fighting)
NOT ALWAYS PHYSICAL
Again, in natural selection to be selectable there must be:
Variability/Heritable variation
Normal distribution
Natural selection depends on:
Non-random mating
In this selection there is one favorable phenotype (extreme) which will shift the curve.—>
Directional Selection
This is characterized by pressure against the average.
Disruptive Selection
Sneaky Salmon
Selection for average against both extremes:
–>()<–
Stabilizing Selection (Siberian Huskies, too big, too small, just right)
Isolated populations can lead to…
Distinct Species
b/c Experiences new pressures
Thus, the old population & new will no longer be able to:
Reproduce
Speciation requires __________ to reproduction.
Barriers
Prezygotic barriers -
Mating or fertilization
Postzygotic barriers -
Developmental
Prezygotic Barriers include:
HTBMG
Habitat Isolation - physical seperation
Temporal Isolation - diff breeding schedule
Behavioral Isolation (Boobies)
Mechanical Isolation - junk don’t fit
Gamete Isolation - inside/outside gametes
Postzygotic Barriers include:
Hybrid invariability -Incompatible genes
Hybrid sterility - Offspring sterile
Hybrid breakdown - Fertile hybrids, offspring don’t survive
Divergence of populations can happen from:
Population separation (Mountains/Barriers) New environmental pressures
When populations diverge…
Allelic frequencies change
- Non-random mating & natural selection
- Genetic drift & mutation
A geographic barrier dividing a population:
Allopatric Separation
-If different environmental pressures = genetic drift & founder effect
Allopatric speciateion is also caused (or was caused by)
Plate tectonics
-Supercontinent Gondewana broke up and everyone changed!
