CELS 191 Lecture 21 Flashcards
(16 cards)
can individuals evolve
no, only populations
what is a population
a localised group of individuals of the same species
what is a gene pool
the total aggregate of genes (and their alleles) in the population at one time
why would we need to estimate frequencies of genotypes in a population
to predict how many individuals will inherit a genetic disease
to estimate the proportion of individuals who are ‘carriers’ of a genetic disease
what must the allele frequency for a dominant allele plus the frequency for a recessive allele equal
1
in terms of genotypic frequency
PP + 2Pp + pp = ___
1
how can allele frequencies change
non-random mating
random genetic drift
bottleneck effect
founder effect
natural selection
gene flow of migration
mutation
what is random genetic drift
a random change in allele frequencies due to sampling error over generations
what is a bottleneck effect
when a population crashes to near extinction but survives. this decreases the amount of genetic diversity within the population
what is the founder effect
when a new population is established by a small group of individuals from a larger, more diverse population
what is stabilising selection and what does this mean on a graph
a reduction in variation that doesn’t change the mean - peak gets higher and narrower
what is directional selection and what does this mean on a graph
a change in the mean value towards one extreme - the peak shifts in one direction
what is disruptive selection and what does it look like on a a graph
a change in mean to favour the two extremes - two peaks form
what is sexual selection
natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.
what is cline
the gradual geographic change in genetic/phenotypic composition
what is frequency dependent selection
an evolutionary process where the fitness of a phenotype or genotype is influenced by its frequency in the population
