▁lead ▁to ▁other ▁ab normal ities ▁like ▁increased ▁met abol ism , ▁higher ▁food ▁consumption , ▁acceler ated ▁heart ▁rate , ▁and ▁delayed ▁sexual ▁m atur ity . ▁ ▁Dom estic ated ▁ch ick ens ▁under w ent ▁a ▁rapid ▁selection ▁process ▁that ▁led ▁to ▁un related ▁phen ot ypes ▁having ▁high ▁correl ations , ▁suggesting ▁ple iot rop ic , ▁or ▁at ▁least ▁close ▁link age , ▁effects ▁between ▁comb ▁mass ▁and ▁phys i ological ▁structures ▁related ▁to ▁re product ive ▁ab ilities . ▁Both ▁males ▁and ▁females ▁with ▁larger ▁comb s ▁have ▁higher ▁b one ▁density ▁and ▁strength , ▁which ▁allows ▁females ▁to ▁depos it ▁more ▁calci um ▁into ▁egg sh ells . ▁This ▁link age ▁is ▁further ▁ev iden ced ▁by ▁the ▁fact ▁that ▁two ▁of ▁the ▁gen es , ▁H A O 1 ▁and ▁B MP 2 , ▁affect ing ▁med ull ary ▁b one ▁( the ▁part ▁of ▁the ▁b one ▁that ▁trans fers ▁calci um ▁into ▁developing ▁egg sh ells ) ▁are ▁located ▁at ▁the ▁same ▁loc us ▁as ▁the ▁gene ▁affect ing ▁comb ▁mass . ▁H A O 1 ▁and ▁B MP 2 ▁also ▁display ▁ple iot rop ic ▁effects ▁with ▁commonly ▁desired ▁domestic ▁ch icken ▁behavior ; ▁those ▁ch ick ens ▁who ▁express ▁higher ▁levels ▁of ▁these ▁two ▁gen es ▁in ▁b one ▁t issue ▁produce ▁more ▁eggs ▁and ▁display ▁less ▁egg ▁inc ub ation ▁behavior . ▁ ▁See ▁also ▁▁▁ ▁c is - reg ul atory ▁element ▁ ▁En han cer ▁( gen et