Download Name: ____________ Pd.: ______ Date: What is the advantage of

Name: _____________________________________________________ Pd.: ________ Date: ______________________
Study Guide – The Evolution of Populations
1. What is the advantage of genetic variation in a population? It increases the chance that some individuals will
survive
2. ___gene pool_________: The combined alleles of all of the individuals in a population.
3. ___allele frequency_______: A measure of how common a certain allele is in the population.
4. What is the allele frequency of allele “G” in the population of frogs below? ___8/16=50%__________________
5. What is the allele frequency of allele “g” in the population of frogs below? ___8/16=50%_______________
6. If predators were able to spot light
colored frogs easier than darker
colored frogs, how would the allele
frequency change in the population
of frogs in future generations?
You would see an increase in the
dark colored frogs
7. The two main sources of genetic variation are __mutation____ and recombination (during sexual reproduction) _.
8. _____mutation____: a random change in the DNA of a gene.
9. Most recombination of genes occurs during the process of ___sexual reproduction___.
10. Another source of genetic variation is ___hybridization_____, or the crossing of two different species that share
common genes.
11. A type of distribution in which the
frequency is highest near the mean
value (average) and decreases toward
each extreme end of the range is called
a ____normal_______ distribution.
12. The observable change in the allele
frequencies of a population over time is
called ___microevolution______.
13. What type of natural selection is shown
in Grapn A?____directional______
In Graph B? ___stabilizing___________
In Graph C? ___disruptive__________
14. Which type of selection favors phenotypes at one extreme of a trait’s range? ______directional_________
15. Which type of selection favors phenotypes of the mean, or average type? ______stabilizing______________
16. Which type of selection favors phenotypes at both extremes of a traits range? ______disruptive___________
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17. The movement of alleles from one population to another is called ______gene flow_____________
18. The less gene flow that occurs between two populations, the more genetically ____different__________ the two
populations become.
19. A lack of gene flow [increases / decreases] the chance that two populations will evolve into different species.
20. A change in allele frequencies due to chance is called _______genetic drift_________________________
21. Genetic drift causes loss of _____genetic diversity________ in a population.
22. ____bottleneck effect__________: genetic drift that occurs after an event greatly reduces the size of a
population.
23. ____founder effect_____________: genetic drift that occurs after a small number of individuals colonize a new
area.
24. Describe two problems that can be caused by genetic drift. ________population loses genetic variation; alleles
that are lethal in homozygous individuals may be carried by heterozygous individuals become more common in
the gene pool by chance___________________________________________________________________
25. How does the cost of reproduction often differ for males and females?
Males produce many sperm continuously therefore the value of each sperm is relatively small and they can make
many investments at a low cost. Females have a limited number of eggs and therefore each investment they
make is more valuable.
26. ______sexual selection_______: occurs when certain traits increase mating success
27. Name and describe the two types of sexual selection;
1. ____intrasexual selection: between the males (fighting)____________
2. ___intersexual selection: when the males display traits to attract the female (peacock feathers)
28. Hardy and Weinberg identified five conditions needed for a population to stay in equilibrium. Populations that
meet these conditions are not evolving. They are said to be in Hardy-Weinberg equilibrium. Name these five
conditions:
1. __very large population: no genetic drift can occur
2. __no emigration or immigration: no gene flow can occur
3. __no mutations: no new alleles can be added to the gene pool
4. __random mating: no sexual selection can occur
5. __no natural selection: all traits must equally aid in survival
29. ___reproductive isolation_______: occurs when members of different populations can no longer mate
successfully with one another.
30. __speciation___________: the rise of two or more species from one existing species
31. Name and describe three ways that populations can become isolated:
1. behavioral isolation: caused by differences in courtship or mating behaviors
2. geographic isolation: involves physical barriers that divide a population into two or more groups
3. temporal isolation: exists when timing prevents reproduction between populations
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32. Tell what type of isolation is occurring in each of the following examples”
____geographic________: a population is separated by a body of water after flooding
____behavioral___________: some members of a population have developed different methods of
courtship than other members of the population
____temporal_______________: Some members of a population begin hunting only at night, while others
continue to hunt during the day
__temporal______________: Some members of a population of trees begin to have different pollination
periods than other members of the population
_____geographic______________: snapping shrimp of the Atlantic and Pacific oceans
___behavioral______________: different patterns of firefly flashes
33. Define each of the following terms:
Convergent evolution: evolution toward similar characteristics in unrelated species
Divergent evolution: when closely related species evolve in different directions
Coevoluton: the process in which two or more species evolve in response to changes in each other
Extinction: the elimination of a species from Earth
Punctuated equilibrium: episodes of speciation occur suddenly in geologic time and are followed by long periods
of little evolutionary change
Adaptive radiation: the diversification of one ancestral species into many descendent species
34. Tell whether each of the following examples show convergent or divergent evolution.
______convergent_____________: the tail fins of fish and marine mammals
______divergent______________: the red fox and the kit fox
______convergent__________: Analagous structures such as wings on birds and insects
35. The fossil record indicates that there have been at least _________5______ mass extinctions in the last 600
million years.
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36. Who am I? Choose among the following terms to answer the riddles below:
Behavioral isolation
geographic isolation
temporal isolation
Hardy-Weinberg equilibrium
normal distribution
punctuated equilibrium
I separate populations with factors of time, such as when one population reproduces in the spring and another
reproduces in the summer: _____temporal isolation________
I look like a bell-shaped curve, having the highest frequency in the middle: _____normal distribution____
I separate populations with physical barriers so that members of each population no longer have contact with
each other: ____geographic isolation_______
I occur when there are no changes in allele frequencies for a certain trait from generation to generation; I rarely
occur in real populations: ____Hardy-Weinbergy equilibrium____________
I am a pattern of evolution that is seen in the fossil record; I consist of short periods with lots of evolutionary
activity, followed by long periods with much less evolutionary activity: ____punctuated equilibrium_____
I separate populations with different courtship or mating rituals. _____behavioral isolation______
37.
microevolution
convergent evolution
coevolution
divergent evolution
Process in which two species evolve in response to changes in each other, over many generations:
___coevolution_________
Process in which unrelated species evolve similar traits while adapting to similar environments:
____convergent
evolution
Process in which closely related species become more and more different as they adapt to different
environments: ______divergent evolution________
Process which can occur over a few generations, in which a population’s allele frequencies change in any way:
_______microevolution_______
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