Bio 123: PP4 Material Flashcards
Define microevolution
The change in allele frequencies in a population throughout time.
Explain the Hardy-Weinberg Equilibrium Model
It is used as a baseline to compare an evolving population to one that remains constant without evolutionary forces acting upon it. There are positive controls and negative controls. There is a part missing, ask classmate for his notes that he wrote
What are the four processes that drive populations out of genetic equilibrium?
1) Mutations
2) Genetic Drift
3) Gene Flow
4) Selection
What are mutations?
Raw material for evolutionary change. They are changes in alleles. They also occur at relatively low rates and can appear more often due to exposure to hazardous material such at radioactive material.
What are the conditions under the Hardy-Weinberg equilibrium?
Evolution is not occurring if:
1) No mutations occur
2) There is no genetic flow (meaning that the population is fully isolated)
3) The alleles present have no effect on the survival or reproduction ability of that population
4) Random mating (there is no active mate choice)
What is the purpose of having a genetic equilibrium model (the Hardy-Weinberg Model)?
It serves to positively identify the mechanisms that drive changes in allele frequency.
Polygenic
Multiple alleles that control a trait
Incomplete Dominance
Bb
Complete Dominance
ignore
Deleterious mutation
Mutations that have a negative affect and decreases an organisms fitness.
Lethal Mutations
Mutations that lead to the death of an organism. The organism is not even born.
Neutral Mutations
Mutations that have 0 affect on an organisms fitness.
Beneficial Mutations
Mutations that have a positive affect on an organisms fitness and is therefore favored by natural selection.
Genetic Drift
In small populations, some alleles can randomly become fixed (one allele can be at 100% and the other ends up at 0%) which causes a loss of some alleles and an overall loss of genetic diversity.
It usually results in a decline of an organism fitness.
What is Homozygous Dominant?
AA
What is Heterozygous?
Bb
Where do we typically see genetic drift occur and why?
In small populations because there is already a much smaller genetic diversity within small populations. It causes allele frequencies to change at random and leads to a loss of genetic variation within a population. It can also cause harmful alleles to become fixed in a population (due to increased inbreeding and mortality).
Explain the Bottleneck Event
In a bottleneck event, some catastrophe (such as a natural disaster or a disease outbreak) occurs and the surviving population only has a fraction of the alleles that were present in the population before the catastrophe.
Explain the Founder Effect
When a few individuals from a population start a new population with a different allele frequency than the original population.
What is the Greater Prairie chicken example?
They only live in undisturbed grassland and because humans have turned grasslands into farming lands, the greater prairie chicken went from having a 5.2 alleles per locus to a 3.7 which reduced their survivorship to less than 50 percent.
What are anthropologically caused events?
Events caused by the human race or through human action.
Define habitat fragmentation
When parts of a habitat are destroyed, leaving behind smaller, unconnected areas.
Define Migration
Movement of alleles between populations.
Define Gene Flow
The transfer of alleles from the gene pool of one population to the gene pool of another population. It causes allele frequencies to shift.
Explain what conservation applications are
Efforts that aim at increasing Gene flow within small populations, promoting genetic diversity across subpopulations such as the use of wildlife corridors.
What were wildlife corridors?
Pieces of land/area that connects populations of the same species that are in different areas in order to promote them to reproduce and increase genetic diversity.
Define Directional Selection
In directional selection, allele frequencies give rise to a range in variation in phenotype that tend to shift in 1 consistent direction. One extreme end of the trait is going to be favored. It can also lead to extreme behaviors such as extreme mating dances.
What happens during Stabilizing Selection?
Neither extreme end is favored. Meaning that the intermediate forms of a trait in a population are favored.
What is an example of Stabilizing Selection?
The Sociable Weaver. Cannot be too small or else they will not be selected by female to mate with and cannot be too big because then they will be slower is escaping predators such as snakes.
What happens during Disruptive Selection?
Forms on both ends of the range of variation are favored and intermediate forms are selected against.
What is any example of Disruptive Selection?
African Finch populations in Cameroon. Small and sharp beaks as well as thicker beaks are favored for depending on the type of food that is available for them.
