chp 17
Compare the phenotypes of polygenic traits to the phenotypes for single-gene traits.
SGT-controlled by a single gene PT-trait controlled by two or more genes
What can disruptive selection lead to?
Speciation
What can directional selection lead to?
Evolution
Define population. B) Are members of the same population members of the same species?
B.yes Pop-members of the same species the live in different areas
Draw a graph for the typical graph of distribution of polygenic traits. B) What is the graph called?
Bell shaped curve
What happened to the birds beaks during the dry season?
Bigger beaks
What does the hox gene control?
Body plans and embryos
____________________________ can be define as a ________________________ in allele frequencies.
Evolution, change
What is the founder effect?
Change in allele frequencies as a result of the migration of a small group of a population
Define and draw the curves for stabilizing selection, directional selection, and disruptive selection. Also know example of each type of selection.
Directional Selection- Form of natural selection when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the end of the curve One extremes Stabilizing Selection- Form of natural selection in which individuals near the center of a distribution curve have higher fitness than individuals at either end of the curve No extreme Disruptive Selection-Natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve Both extremes
What is the Hardy-Weinberg Principle?
Five conditions are required to maintain genetics equilibrium 1.large Pop. 2.no mutations 3.random mating 4.no movement in/out population 5.no natural selection
What is genetic drift? B) What conditions need to happen for genetic drift to occur
GD-random change in allele frequencies that occurs in small populations Occurs in small populations
What is the first step that occurred in the speciation of the Galapagos finches?
Geographic isolation
Due to a mutation, a new fur color (orange) occurred in a population of rabbits. How will we know how this color affects the fitness of the rabbits?
If the orange rabbit survive to the next generation then it hasn't
What are the three sources of genetic variation?
Mutation, genetic variation during sexual reproduction, lateral gene transfer
What does natural selection act on?
Phenotype
What is reproduction isolation? B) Name and define the three types of reproductive isolation.
RI-condition in which a reproductive barrier keeps two species from interbreeding Behavioral Isolation- type of reproductive isolation in which two organisms have different mating rituals that prevent them from interbreeding Geographical Isolation-type of reproductive isolation in which two different species live in different habitats Temporal Isolation-form of reproductive isolation in which two populations reproduce at different times
What factor is necessary for the formation of a new species?
Reproductive isolation
Define species
a group of organisms so similar to one another that they can breed and produce fertile offspring
What is meant by the term genetic equilibrium?
allele frequencies remain constant.
What were the two testable assumptions that the Grants studied?
beak size changed as a result of changes in food supply Galápagos finches could have evolved from a common ancestor.
Define gene pool.
combined genetic information of all the members of a particular population