mutation, migration, and selection. can predict the amt of change in gene freq. and the direction of change
chance, can predict amt. of change in gene freq. but NOT direction of change
involves differential rates, when indiv. allowed to produce more offspring than others. Most powerful force we have to change gene freq.
Goal of Selection
increase freq. of genes.; involves saving or culling whole animals w/ all of their genes
occurs in nature w/o human help.; "survival of the fittest"
selection done by humans
affected by 1 to very few genes; few, distinct phenotypes; gives rise to DISCONTINUOUS VARIATION; environ. not much affect
controlled by many genes (POLYGENIC CONTROL-except MAJOR GENES), many phenotypes, CONTINUOUS VARIATION, affected to large degree by environ.
MAJOR GENE Examples
1. Booroola Merino gene 2.postweaning wt in mice 3. Double muscling gene (myostatin mutation) 4. Callipyge gene 5. Halothange Gene 6. Dwarf Genes
dorset sheep; originated from ram called "solid gold", increase muscling, decr. fat, meat very tough
Halothane gene (stress gene)
reduced litter size, growth rate, and carcass length. increased loineye area and lean%, causes PSE
Two categories of Statistics
Central Tendency and variaiton (measures of)
average squared deviation of individual measurements from the mean; 0 to infinity
characteristic of the variation