Term
| Gene frequencies. How can they be calculated? |
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Definition
Allele frequency calculation
1. Punnett square for individuals
2. Allele frequency in populations
200 possible alleles in 100 individuals.
T t
20 TT 40 0
40 Tt 40 40
40 tt 0 80
Totals: 80 T, 120 t
Frequencies: T = 80/200, 40%
t = 120/200, 60%
Next generation:
can assign gene frequencies
Ova
T = .4 t =.6
Sperm T = .4 TT .16 Tt: .24
t = .6 Tt .24 tt: .36
Next gen: 16 TT, 48 Tt, 36 tt
T t
16 TT 32 0
48 Tt 48 48
36 tt 0 72
T: 80, t: 120 (as last generation)
Process of reproduction does not change gene frequencies by itself. |
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Term
| Define: evolution and microevolution |
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Definition
Evolution: A change in a population over time.
Microevolution: the change in gene (allele) frequencies in a population over time. These changes may or may not coincide with visible phenotypic changes. |
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Term
| How do different factors affect variation? Non-random breeding, genetic drift, selection, gene flow, genetic drift, and mutation. |
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Definition
1. nonrandom mating (reduces variation)
2. Genetic drift (reduces variation): the role of chance in inducing nonrandom fertilization events (e.g. flipping a coin thousands of times will result in a near 50/50 distribution. If you do it 100 times, could have 60/40. 10 could be an even greater deviation from the even distribution)
Population bottlenecks (large number of individuals are pruned to a much smaller number). Populations under 30 individuals see a lot of genetic drift
3. Selection (reduces variation)
4. Migration (increase variation)
5. mutation (increases variation) |
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Term
Peppered moth example
How can selection result in microevolution? |
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Definition
| Peppered moth is example of directional selection --> selected towards looking like sooty trees. |
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Term
| What are stabilizing selection, directional selection, and disruptive selection? Give examples |
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Definition
Stabilizing selection: extremes are selected against (human head size at birth: pinheads do not survive well, too large tends to kill mother). Much broader again b/c of c-sections and saving premies
Directional selection: a certain trait is selected for (shifts entire distribution)
Disruptive selection: select against the median in favor of extremes (less common, very disruptive) |
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Term
| Understand how the recessive allele for sickle cell anemia confers resistance to malaria in heterozygous individuals. How is this an example of balanced polymorphism? |
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Definition
HbA=normal hemoglobin HbS= sickle hemoglobin
HbAHbA=normal hemoglobin
HbSHbS=sickled hemoglobin
HbAHbS=heterozygote for sickle cell trait (not sickle celled, provides malaria resistance) |
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Term
| define and give examples of macroevolution |
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Definition
| macroevolution: on the scale of the formation of new populations or the extinctions of a population. |
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Term
| Darwin's 4 hypotheses regarding natural selection |
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Definition
1. Variation: there is variation among individuals in a population.
2. That variation is heritable
3. Variation leads to differences in adaptedness to environment
4. The variation leads to reproductions favoring advantageous traits. This leads to the formation of a new species. |
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Term
| Darwin's logical inferences for evolution by natural selection. |
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Definition
| Evidence: Fossil records and extant species (ones still alive) |
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Term
| General patterns in fossil record |
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Definition
| General pattern: not a straight line, has explosions and extinctions over time. |
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Term
| How do Darwin's finches provide support for the theory of evolution? |
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Definition
| 14 total species. Each are specialized for specific diets. |
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Term
| Define: adaptive radiation and species flocks |
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Definition
Adaptive radiation: several different species from one ancestral species with different adaptations
Species flocks: groups of species that are similar in several aspects from adaptive radiation. |
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