pt oph ane ▁to ▁k yn uren ine , ▁verm il ion ▁f lies ▁lack ▁the ▁ability ▁to ▁convert ▁these ▁am ino ▁ac ids ▁blocking ▁the ▁production ▁of ▁brown ▁p ig ment . ▁The ▁reduction ▁in ▁the ▁amount ▁of ▁try pt oph an ▁converted ▁to ▁k yn uren ine ▁in ▁verm il ion ▁mut ants ▁has ▁been ▁associated ▁with ▁longer ▁life ▁sp ans ▁in ▁comparison ▁to ▁wild - type ▁f lies . ▁ ▁v g : ▁v estig ial - ▁A ▁sp ont aneous ▁mut ation , ▁discovered ▁in ▁ 1 9 1 9 ▁by ▁Thomas ▁Morgan ▁and ▁Cal vin ▁Br id ges . ▁V estig ial ▁wings ▁are ▁those ▁not ▁fully ▁developed ▁and ▁that ▁have ▁lost ▁function . ▁Since ▁the ▁discovery ▁of ▁the ▁v estig ial ▁gene ▁in ▁D ros oph ila ▁mel an og aster , ▁there ▁have ▁been ▁many ▁discover ies ▁of ▁the ▁v estig ial ▁gene ▁in ▁other ▁verte br ates ▁and ▁their ▁functions ▁within ▁the ▁verte br ates . ▁The ▁v estig ial ▁gene ▁is ▁considered ▁to ▁be ▁one ▁of ▁the ▁most ▁important ▁gen es ▁for ▁wing ▁formation , ▁but ▁when ▁it ▁becomes ▁over ▁expressed ▁the ▁issue ▁of ▁e ct op ic ▁wings ▁begin ▁to ▁form . ▁The ▁v estig ial ▁gene ▁acts ▁to ▁reg ulate ▁the ▁expression ▁of ▁the ▁wing ▁imag inal ▁disc s ▁in ▁the ▁emb ry o ▁and ▁acts ▁with ▁other ▁gen es ▁to ▁reg ulate ▁the ▁development ▁of ▁the ▁wings . ▁A ▁mut ated ▁v estig ial ▁alle le ▁removes ▁an ▁essential ▁sequence ▁of