families to population Flashcards
what is microevolution
change in allele frequency of population from one generation to the next
the difference between phenotypic variation and genotypic variation
genotypic variation is caused by genetic mutation while phenotypic variation is only if that mutation is displayed (appearance/function)
examples of quantitative and qualitative variation and relation to locus
quantitative would be weight, height, etc it is controlled by many loci. qualitative is colour of snow geese feather (blue/white) etc it is generally controlled by a single locus.
why we care whether phenotypic variation is caused by genetic differences, environmental factors, or both
this is because only genetically based variation is inherited and subjected to evolutionary change
how we might test whether phenotypic variation is caused by genetic differences, environmental factors, or both
test for environmental factor by altering the environmental variable and measuring effects on genetically similar subjects.
difference between “allele”, “locus”, and “gene pool”
allele is the variant form of a gene. locus is the location of a gene on a chromosome. gene pool is the total genetic variability of population by all alleles by all gene loci in all individuals within population
meaning of “allele frequency” and “genotype frequency”
allele frequency is the percentage of all copies of a certain gene in a population that carry a certain gene; gene frequency is a percentage of individuals in a population that have a certain genotype
Conditions that must be met for HWE to occur
NO GENE FLOW population closed to migration from other populations; INFINITE POPULATION SIZE; NO MUTATION occurring in population; NO SELECTION all genotypes in population survive and produce equally well; RANDOM MATING individuals in population mate randomly with respect to genotype.
What it means if a population is in HWE at a locus?
it means that the concentration of alelles stay; the same
and the phenotype count also stays the same
How mutation, selection, gene flow, genetic drift, and non-random mating can take a population out of HWE
mutation introduces new alleles; geneflow introduces new alleles due to migration; selection favours combo of traits over another leading to differential survivorship and preproduction; genetic drift is when the frequency of alleles change in gens by chance; nonrandom mating causes HWE to not be maintained bc itself doesnt result in change in allele frequencies & thus not considered microevolutionary process (birds choosing mate based off of appearance)
Meaning of directional selection
directional selection is when individuals near one end of phenotypic spectrum have highest relative fitness - shifts a trait away from existing mean and towards the favoured extreme. after, traits mean value is higher/lower than before and variability may be reduced
Effect of heterozygote advantage or disadvantage on allele frequencies and genetic variation
advantage: it maintains genetic variation (keeps alleles in population) = balancing selection; rare alleles increase in frequency, common alleles decrease in frequency - leading to 0.5 frequency.
HWE EQUATION
it uses the (p+q)^2 distribution to count how many individuals have a certain phenotype or allele
Meaning of stabilizing selection
stabilizing selection is when individual expressing intermediate phenotypes have highest relative fitness. eliminates phenotypic extremes, reducing genetic and phenotypic variation and increases frequency of intermediate phenotypes
Meaning of disruptive selection
disruptive selection is when extreme phenotypes have higher fitness than intermediate phenotypes thus becoming more common
when can heterozygote advantage/disadvantage occur?
only if heterozygotes have diff phenotype that either homozygotes.
what is absolute fitness? relative fitness? what does a high relative fitness indicate?
number of surviving offsprings for each genotype. relative fitness is absolute divided by the absolute of the most fit genotype. a high relative fitness means more favoured by selection in the environment
what will a heterozygote advantage lead to?
it will lead to allele frequencies stabilizing near 0.5. once stabilization has occurred selection is still occurring but no evolution genetic variation maintained
what will a heterozygote disadvantage lead to?
more common allele frequency increases to 1 and less common allele vanishes. genetic variation decreases
what are the types of selection?
directional, stabilizing, disruptive and balancing
what is genetic drift?
allele frequencies changing due to chance. includes population bottlenecks (major event) and founder effect (small number move and start new population). it is unpredictable
what does non random mating do? what are the types?
doesnt change allele frequencies - just the genotypic frequencies; the types include associative/inbreeding (homozygous) and dissociative (heterozygous)
what is assortive mating?
homozygosity
what disassortive mating?
heterozyogisty
