what is microevolution
change in allele frequency in population/species across generations
–> evolutionary change over shorter time periods
what is macroevolution
evolution above species level –> variation among species and questions related to diversification
–> over long periods of time
(T/F) macroevolution is the results of microevolution
T
what are the 4 processes that can cause microevolution
- mutation
- gene flow
- genetic drift
- natural selection
what does microevolution NEED
genetic variation
what is panmixia
random mating in a population
what is random mating
individuals mate randomly with respect to their genotype at locus of interest
what is non-random mating
mating system in which at least some individuals are more or less likely to mate with individuals of a particular genotype than with individuals of other genotypes
–> more common
why is mating often non-random
- relatives may mate more often or less often than expected by chance
- individuals may self-fertilize more or less often than expected by chance
- individuals may mate more often with others more or less similar to them in phenotype than expected by chance
what is inbreeding
when mating takes place between related individuals
–> resulting offspring are inbred
what are the effects of inbreeding
can cause increase in frequency of homozygotes
–> 1+ generations of random mating may restore HW ratios
what is inbreeding depression
decrease in fitness as a consequence of inbreeding
–> can increase loss of gene variation that occur in small populations due to genetic drift
what are the 2 mendelian causes of inbreeding depression
- dominance hypothesis: alleles that decrease fitness (deleterious alleles) tend to be partially-completely recessive –> homozygosity will increase expression of these alleles
- heterozygote advantage: heterozygotes have higher fitness than either homozygotes –> increased homozygosity = lower fitness
what is outbreeding
mating between individuals that are less related
what are the effects of outbreeding
increases heterozygosity
what is heterosis
increase in fitness relative to non-outbred individuals
how does heterosis occur
- deleterious alleles more likely to be masked
- heterozygotes have higher fitness
what is a mutation
a change in genetic information of an organisms DNA
what are the effects of mutation
can create new alleles –> ultimate source of genetic variation
–> RANDOM
when are mutations heritable
if they are present in the germ line
what are the types of mutation
small scale (point mutation):
- substitution: single nucleotide is replace with another –> silent or replacement
- insertion/deletion: 1+ nucleotide is added or removed
large scale: mutations in chromosomal structure
- translocation
- inversion
- duplication
(T/F) most new mutations are beneficial
F
what is gene flow (AKA migration)
movement of alleles between populations occuring via migration
–> introduces/removes alleles from populations
what are the effects of gene flow
homogenizes populations –> reduced genetic variation
