BIOC51H3 Lecture 17: BGYB51H3 Lecture 17 Notes Nov 5
11 Aug 2010
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BGYB51H3 Lecture Notes
-selection differential is the mean value of trait between successful breeders and whole
population
S = P* - P
-if S>0, increase in trait value, if S<0 decrease in trait value, S=0 mean trait value
-larger values of S, stronger selection occurring
-the closer S is to the population mean, weak selection
-R is the evolutionary response to selection
R = O* - O
-O means that there is no evolutionary change and is an estimate from P
O* - O rise R
h2 = ______ =____ =___ R = h2S
P* - P run S
-heritability is the response to the selection divided by the selection differential
-even if strong selection, if heritability is low there is low direction of change in offspring
-relative fitness is the number of surviving offspring divided by mean number of surviving
offspring
-selection gradient is the relation between trait value and fitness
-selection gradient is more commonly measured than selection differential
S = selection gradient/variance
-coevolution is when interacting species experience reciprocal evolutionary change due to
natural selection imposed by each on the other
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Document Summary
Selection differential is the mean value of trait between successful breeders and whole population. If s>0, increase in trait value, if s<0 decrease in trait value, s=0 mean trait value. The closer s is to the population mean, weak selection. O means that there is no evolutionary change and is an estimate from p. O* - o rise r h2 = ______ =____ =___ r = h2s. Heritability is the response to the selection divided by the selection differential. Even if strong selection, if heritability is low there is low direction of change in offspring. Relative fitness is the number of surviving offspring divided by mean number of surviving offspring. Selection gradient is the relation between trait value and fitness. Selection gradient is more commonly measured than selection differential.
