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15 Cards in this Set

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gene pool
the combined genetic information of all the members of a particular population
relative frequency
an allele is the number of times that allele occurs in a gene pool compared with the number of times other alleles occur
genetic variation
the two main sources of genetic variation are MUTATIONS and the GENE SHIFFLING that results from sexual reproduction
gene shuffling
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
crossing over
increases the number of different genotypes that can appear in offspring
single gene trait
contolled bya single gene that has two alleles
natural selection
only works on phenotypes expression of the gene
polygenic traits
msot traits are controlled by two or more genes and are polygenic
-has two or more alleles
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
what is the habitat like?
lizards-dark habitat
this is an example of natural selection
directional selection
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
what is an example of directional selection?
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
stabilizing selection
when individuals near the CENTER of the curve have the higher fitness than individuals at either end of the curve
example of stabilizing selection
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
disruptive selection
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.