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15 Cards in this Set
- Front
- Back
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gene pool
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the combined genetic information of all the members of a particular population
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relative frequency
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an allele is the number of times that allele occurs in a gene pool compared with the number of times other alleles occur
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genetic variation
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the two main sources of genetic variation are MUTATIONS and the GENE SHIFFLING that results from sexual reproduction
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gene shuffling
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takes place during meiosis when corssing over occurs
-doesnt change frequencies -may break up, but alleles are still there; dont get lost -occur during the production of gametes |
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crossing over
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increases the number of different genotypes that can appear in offspring
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single gene trait
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contolled bya single gene that has two alleles
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natural selection
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only works on phenotypes expression of the gene
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polygenic traits
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msot traits are controlled by two or more genes and are polygenic
-has two or more alleles |
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over generations what occurs?
what is selected out? |
the bright ones will be selcted out
over time the bright ones would [ass fewer copies of their alleles for red coloring to future generations |
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what is the habitat like?
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lizards-dark habitat
this is an example of natural selection |
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directional selection
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when individuals at one end ofthe cuve hve higher fitness than individuals in the middle or the other end
-causes entire curve to move as the character trait changes |
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what is an example of directional selection?
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peppered moths. indisutrail rev. comes along and all the soot gets on the trees and the black survive and the lighter ones die faster but when the soot start to go the lgihter survive and darker die
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stabilizing selection
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when individuals near the CENTER of the curve have the higher fitness than individuals at either end of the curve
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example of stabilizing selection
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mortality for babies.
-picks out extremes unless something changes, results in equilibrium. -when a baby is smaller it is less likely to survive - when a baby is bigger it is going to have a harder time being born -therefore the fitness is lower than the average baby's |
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disruptive selection
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when individuals at the upper end and lower ends of the curve have higher fitness than individuals near the middle
-birds. a populations that has small and big seeds may only have brids with small beaks or big beaks survive longer and reporoduce medium birds will have a harder time. |
