lecture 19 Flashcards
what is a population?
group of individuals of one species found at same location at same time
what is migration?
movement of individuals from one pop to another
what is gene flow?
movement of genes from one pop to another
diff from migration as not all species reproduce by mating
ex. some species just randomly release gametes and hope for the best
what are the difficulties to measuring gene flow?
have to distinguish b/w potential and actual gene flow, not all migration leads to gene flow
have to distinguish gene flow at gamete level or individual level (gene flow vs migration)
what is the relationship b/w gene flow and selection
they are opposites
selection pulls pops apart and help pop develop independent traits and adapt to environment
gene flow pulls pops together, slows down accumulation of diffs and prevents independent evolution
how can gene flow be measured?
diff pops w/ diff genetics can be set up within a known distance to observe gene flow
why types of genetic markers shld be used to study gene flow and why?
nusually want to use neutral genetic markers/polymorphic markers to study diversity affecting processes (genetically based, inheiratance followable, neutral (no affect to survivorship/reproduction)
this is because if genetic marker affects survival or reproduction its difficult to tell if gene dying at new location (selection) or not getting to new location at all (lack of gene flow/not all individuals/gamets make it to all localities)
what is a quantifiable measurement of gene flow?
frequency of heterozygotes b/w two homozygous pops
ex. finding progeny which cld only be created from outcrossing of crops and weed sunflowers
how does gene flow relate to distance?
majority gene flow only travels a very short distance, but a minority of gene flow can occur long distance as well
what is a stochastic force?
describes unpredictable/random evolutionary forces
ex. genetic drift, recombination, mutation
what are pop bottlenecks?
sharp reduction in pop number which leads to loss of diversity
what is a founder event and how does it relate to genetic diversity?
colonization of new localities by few individuals usually involves a small sample of source pop genetic diversity/variation
what is deterministic evolutionary forces?
opp of stochastic determination
means some individuals have an advantage and will survive/reproduce better than others
ex. natural selection and phenotype advantage
what is the impact of low gene flow?
means genetic diffs in two pops will be maintained, since chromosomes w/ a particular set of mutations in a particular pop are not making it to the the other pop and so there will be greater dna sequence divergenc
what is the impact of high gene flow?
most mutations present in one pop will also be in another pop, less dna sequenct divergence
