evolutionary processes Flashcards
where does heritable variation in traits come from?
- some genetics
what are basic traits determined by?
genes
what is the location where a gene can occur called?
locus (plural: locai)
what is a particular version of a gene called?
allele
how many allele’s does a complex organism usually have at each locus?
- 2 (they can be the same or different)
different alleles at a locus
heterozygous
same alleles at a locus
homozygous
genotype
collection of an individual’s genes
phenotype
collection of an individual’s physiological and physical traits
what does it mean for a population to be in hardy weinberg equilibrium?
this is when a population’s genotype and phenotype frequencies stay constant from generation to generation (no evolution is occurring)
what is needed for a population to be in HWE?
- large population size
- no immigraton/emigration
- no mutation
- no natural selection
- random mating
why is HWE called a null model?
- it tells us what to expect if complicating effects are ABSENT
what are the types of natural selection?
- stabilizing
- directional
- disruptive
- balancing
directional and multidirectional selection?
- tends to move the population in a certain direction
- multidirectional selection is directional selection that can change through time based on the environment
- it favours one extreme trait over another extreme
stabilizing selection?
- tends to keep the population where it is
- favours intermediate trait over extreme trait
what is the connection between directional and stabilizing selection?
- directional selection can lead towards stabilizing selection
- a lot of traits that we see was a result of directional selection leading towards stabilizing selection
disruptive selection
- favours the extreme trait over the intermediate trait
- can lead to speciation as genetic variance increases
balancing selection
- when there is no “best” allele so allele diversity is maintained
what is heterozygote advantage
- when heterozygous have a higher fitness
what is frequency dependance
when rare types have a higher fitness
genetic drift
- change in allele frequency due to random sampling when a population is small
- reduces genetic variation
founder effect
- a special case of the bottleneck effect
- occurs when a small group in the population breaks off and forms a new population
bottleneck effect
- population becomes significantly smaller over a period of time due to some random environmental effect
- it can then become big again after
gene flow
- allele movement from one population to another
- it’s against speciation as it keeps populations similar
