lecture 2- phenotypic plasticity Flashcards
evolution… population or individual
always within population
define evolution
change in the proportion of alleles within a population across generations
phenotype
trait
allele
variant of each gene… eg eye colour
polymorphism
different forms of genes– ie allows for natural selection bc creates variation
4 main forces evolution
mutation
gene flow
genetic drift
natural selection
mutation
original source of heritable variation
totally random
occurs during meiosis
can be good or bad or neutral
gene flow
migration-daily effects small pops- shift in distribution of alleles
if pop is big gene flow doesn’t have a very big effect
genetic drift
a) founders effect-effects smaller pops, very random event, few from a pop migrate and from new pop and by chance the founders of population all have same 1 allele
b) bottleneck effect- chance event, causes shift in allelic variance, usually natural disaster
Natural selection
NOT RANDOM- adaptive shift in population to increases fitness
neutral trait evolution
result of gene flow, genetic drift and mutations— NO directionality
Breeders equation
R=SxH^2
R is magnitude of evolutionary response
S is strength of selection
H is heritability of the trait (b/w 0 & 1)
does evolution happen without NS
yes- many events can lead to evolution… ie gene flow
NS without evolution
No- selection of trait is dependent on environment and is non-heritable
in breeders eq R=S bc H^2=0
phenotypic variation
Vpehnotype=Vgenotype + Venvironment
