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Traits are expressed at an..
Evolution happens at a...
Change in the allele frequency of a population over time
are always evolving, which means that allele frequencies in their gene pool are always changing over generations.
Mutation is the source of new alleles
The population is infinitely large
The population is isolated from all other populations of the species (no gene flow)
All individuals survive and produce the same number of offspring
Evolution is an opportunistic process.
Dramatic shifts have a tendency to occur to smaller populations rather than larger ones.
Violation of GE 5
- Natural selection
- a. Directional selection: one extreme or other extreme of parabola : environment favored selection
- b. Stabilizing selection: Middle of parabola. extreme forms become lessened
- c. Disruptive selection: both sides of parabola: extreme forms favored by environment.
Violation of GE 4
- Sexual selection; individuals with more attractive traits, better being able to attract mates for off spring generating.
- ex. peacock tails
Violation of GE 2
- Genetic Drift: Stochastic fluctuation in allele frequency of a population over time.
- Stochastic= Random
- ex. Bottle neck effect: drastic reduction in population size, brought about by SEVERE PRESSURE or a random event.
- aka. selective pressure
- some alleles are no longer going to be present.
- Founder effect- migration of alleles vs. dying off
Violation of GE 3
gene glow: movement of alleles among population
Pre-zygotic isolation mechanism, how many?
1- Temporal Isolation
- 2- Mechanical Isolation
- 3- Behavioral Isolation
- 4- Ecological Isolation
- 5- Gametic incompatibility
Indv. of diff populations can evolve and reproduce at diff times
instability to reproduce because of physical incapability
ind. of one pop. may not be attracted to an indv. of another pop
indv. are in diff places and do not meet
reproduction cells meet up but do not fertilize
Post Zygotic Isolation
- 1- Hybrid Inviability
- 2- Hybrid Sterility
process by which idv. diverge into separate liniages and become diff species
hybrid, idv. die before they can reproduce
hybrid ind. unable to produce offspring, unfunctional gametes
no physical separation between populations
physical separation between species
Biological Species concept
species are groups of interbreeding natural populations that are REPRODUCTIVELY ISOLATED FROM OTHER SUCH GROUPS.
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