▁a ▁pseud ogene . ▁Pseud ogen es ▁can ▁be ▁lost ▁over ▁time ▁due ▁to ▁gen etic ▁mut ations . ▁Ne of unction al ization ▁occurs ▁when ▁one ▁copy ▁of ▁the ▁gene ▁accum ul ates ▁mut ations ▁that ▁give ▁the ▁gene ▁a ▁new , ▁benef icial ▁function ▁that ▁is ▁different ▁than ▁the ▁original ▁function . ▁Sub function al ization ▁occurs ▁when ▁both ▁copies ▁of ▁the ▁redundant ▁gene ▁ac quire ▁mut ations . ▁Each ▁copy ▁becomes ▁only ▁partially ▁active ; ▁two ▁of ▁these ▁partial ▁copies ▁then ▁act ▁as ▁one ▁normal ▁copy ▁of ▁the ▁original ▁gene . ▁Figure ▁ 2 ▁to ▁the ▁right ▁provides ▁a ▁visual ▁explanation . ▁ ▁Gene ▁Main ten ance ▁Hyp oth eses ▁ ▁The ▁evolution ▁and ▁origin ▁of ▁redundant ▁gen es ▁remain ▁unknown , ▁largely ▁because ▁evolution ▁happens ▁over ▁such ▁a ▁long ▁period ▁of ▁time . ▁The oret ically , ▁a ▁gene ▁can ▁not ▁be ▁maintained ▁without ▁mut ation ▁unless ▁it ▁has ▁a ▁select ive ▁pressure ▁acting ▁on ▁it . ▁Gene ▁redund ancy , ▁therefore , ▁would ▁allow ▁both ▁copies ▁of ▁the ▁gene ▁to ▁accum ulate ▁mut ations ▁as ▁long ▁as ▁the ▁other ▁was ▁still ▁able ▁to ▁perform ▁its ▁function . ▁This ▁means ▁that ▁all ▁redundant ▁gen es ▁should ▁theoret ically ▁become ▁a ▁pseud ogene ▁and ▁eventually ▁be ▁lost . ▁Scient ists ▁have ▁de vised ▁two ▁hypothesis ▁as ▁to ▁why ▁redundant ▁gen es ▁can ▁remain ▁in ▁the ▁gen ome : ▁the ▁backup ▁hypothesis ▁and ▁the ▁p ig gy back ▁hypothesis . ▁ ▁The ▁backup ▁hypothesis ▁propos es ▁that ▁redundant ▁gen es ▁remain