Polygenic Traits

polygenic traits shown continuous variation in ex population . ) A,B, C Dark influences skin color alleles and light alleles . * Intermediate parents Chanute Mendel • variation in trait due to different alleles seyrey-aterandomlyintogamete.org • Alleles anism inherit two may have extreme child in . alleles from each trait . heterozyyotesdeterm-inedbydminantal eles.RO • . Appearance of ✗ Pp gametes from * * random each parent sexually combined . . = ex) flower have 42 chance white of getting parent and 12 chance of getting other : Ya chance of being white p ' one . . p from from Diploid cell female parent Meiosis in male , both Diploid cell parent in in male gamete formation female and . Fertilization ✗ ✗ Reciprocal * Kendal crosses never mattered ✗ y XX xx XX illustrates XY sex linkage in Drosophila which parent had which gene . . • When traits the are genotype sex of linked it matters the , parents . • • Alleles of two genes * Both two genes are assort independently independent in dihybrid from each other ( crosses nothing Xi and Y chromosomes homologs behave like pair at meiosis . . to do with ) 9 :3 :3 :| classicist mehdehun genetics . of ← random i. . dihybid individual makes 4 types of gametes . Q It start with we A) Allele frequency Q If A Q In A frequency does starting should know Applying , parent common is , and a recessive and dominant alleles that is eventually happen ? what will rare , change alleles that recessive a large population a alleles that dominant does not start with we Allele a change not in the absence of to common , alleles that is what rare , eventually happen ? will . allele trexuency square is selection what influences future allele frequency , . . population . W R - - - - brown red . allele fregency = 604W . 40-1 R . homozygosew = 0.36 heterozygote 0.48 homozygote 13=016 = WW WR * Two • WR Hardy Weinberg - ratio Let . . f- (A) . fat / All p2 1- (Ai,Ad=2pq , = f- ( Az, Az ) = y " =p FCA a) =p . RR get ways to become alleles from heterozygote parents both . Hardy • - Weinberg large In em principle mating population random , migration, and there are , where mutations noselect_ (equal are rare fitness ) ( ignored ) of with , immigration or d hogehetlow-o.tl/t,,A,)--p2 ↳ It • • is able to 1- ( Ai Az ) ⇒ py 1- (Az ,Az ) ya - - calculate genotype frequency ( using allele frequency) Hardy Weinberg . . . ratio : only happens when allassumptionaremade.ro mutation rare • • Use observed phenotype or genotype frequencies to genetic flow no no selection calculate allele frequencies Multiply Since CR Use . 2 homozygotes . = should always be diploid . 1 . cell ! product rule to calculate the expected genotype treiuencies ( under HWEI frequency CR = CW frequency • 0.7 , • 0.3 = • ①( " " Cc (WV frequency frequency = 0.7×0.7=0 .gg 2 = (0.3×0-9)=042 0.09 frequency i-tisinHWE.n.se/ectionispreseht.# = (03×03) f- ( A , A = . , )=p2 1- (11-1/1-2)=2 pg f (A- 2,11-21=42 . Hardy Weinberg is - To ' recognize evolution tenens If not - . know what to need we , non a - evolving population looks be predicted from allele frequencies population WIIG while this is true (no euolutonary force) genotype frequencies If • null model a can , is like . Hardy Weinberg equilibrium .lt/WE/ in - at this locus . moreass-umpt.no/-HWE violated , the populationmaybeevolviny.fi/ness • one , and • For each or the strength genotype , selection of . estimate can we are absolute fitness (w ) ↳ average ↳ average relative fitness ( ) by definition fittest genotype w all other, W/Wmax . w - , has w= I - - - - In diploid difference organism, in w between dominance genotype reflects strength relationship can constrain selection of selection . . • • It dominant """ " " - mututon it arise, would increase """ "°" "" " Recessive allele stillinthepopulaton " ↳ inside ÷¥ rapidly . °" heterozygote . ¥¥÷ time allele " " recessive *¥ ¥÷¥ # " "" population • . "" """"" " " . could out compete dominant allele non - favorable . time * No genetic disorder in natural selection would dominant allele If there . apply . is , " .