▁in ▁the ▁gen ome ▁as ▁a ▁sort ▁of ▁" back - up ▁plan ". ▁If ▁the ▁original ▁gene ▁los es ▁its ▁function , ▁the ▁redundant ▁gene ▁is ▁there ▁to ▁take ▁over ▁and ▁keep ▁the ▁cell ▁alive . ▁The ▁p ig gy back ▁hypothesis ▁states ▁that ▁two ▁par al ogs ▁in ▁the ▁gen ome ▁have ▁some ▁kind ▁of ▁non - over la pping ▁function ▁as ▁well ▁as ▁the ▁redundant ▁function . ▁In ▁this ▁case , ▁the ▁redundant ▁part ▁of ▁the ▁gene ▁remains ▁in ▁the ▁gen ome ▁due ▁to ▁the ▁proxim ity ▁to ▁the ▁area ▁that ▁codes ▁for ▁the ▁unique ▁function . ▁The ▁reason ▁redundant ▁gen es ▁remain ▁in ▁the ▁gen ome ▁is ▁an ▁on going ▁question ▁and ▁gene ▁redund ancy ▁is ▁being ▁studied ▁by ▁research ers ▁everywhere . ▁There ▁are ▁many ▁hypoth eses ▁in ▁addition ▁to ▁the ▁backup ▁and ▁p ig gy back ▁models . ▁For ▁example , ▁at ▁the ▁University ▁of ▁Michigan , ▁a ▁study ▁provides ▁the ▁theory ▁that ▁redundant ▁gen es ▁are ▁maintained ▁in ▁the ▁gen ome ▁by ▁reduced ▁expression . ▁ ▁Research ▁ ▁Gene ▁Famil ies ▁and ▁Ph y log eny ▁ ▁Research ers ▁often ▁use ▁the ▁history ▁of ▁redundant ▁gen es ▁in ▁the ▁form ▁of ▁gene ▁families ▁to ▁learn ▁about ▁the ▁ph y log eny ▁of ▁a ▁species . ▁It ▁takes ▁time ▁for ▁redundant ▁gen es ▁to ▁under go ▁functional ▁divers ification ; ▁ ▁the ▁degree ▁of ▁divers ification ▁between ▁orth olog s ▁tells ▁us ▁how ▁closely ▁related ▁the ▁two ▁genom es ▁are . ▁Gene ▁dup lication ▁events ▁can ▁also