▁species ; ▁for ▁instance , ▁it ▁is ▁shown ▁that ▁sequences ▁of ▁mit och ond rial ▁origin ▁promote ▁nuclear ▁DNA ▁rep lication ▁in ▁Sac char omy ces ▁c ere vis iae . ▁Although , ▁the ▁extended ▁trans location ▁of ▁m t D NA ▁fragments ▁and ▁their ▁co - am pl ification ▁with ▁free ▁mit och ond rial ▁DNA ▁has ▁been ▁problem atic ▁in ▁the ▁diagn osis ▁of ▁mit och ond rial ▁dis orders , ▁in ▁the ▁study ▁of ▁population ▁gen et ics , ▁and ▁ph y log en etic ▁anal ys es , ▁scient ists ▁have ▁used ▁NUM T s ▁as ▁the ▁gen etic ▁markers ▁to ▁figure ▁out ▁the ▁relative ▁rate ▁of ▁nuclear ▁and ▁mit och ond rial ▁mut ation ▁and ▁recre ating ▁the ▁evolution ary ▁tree . ▁ ▁Br ief ▁History ▁of ▁NUM T ▁By ▁the ▁end os ym b ios is ▁theory , ▁which ▁gained ▁accept ance ▁around ▁the ▁ 1 9 7 0 s , ▁the ▁mit och ond r ion , ▁as ▁a ▁major ▁energy ▁factory ▁of ▁the ▁cell , ▁was ▁previously ▁a ▁free - l iving ▁pro k ary ote ▁that ▁inv aded ▁a ▁e uk ary otic ▁cell . ▁ ▁Under ▁this ▁theory , ▁sym bi otic ▁organ elles ▁gradually ▁transferred ▁their ▁gen es ▁to ▁the ▁e uk ary otic ▁gen ome , ▁imp lying ▁that ▁m t D NA ▁was ▁gradually ▁integrated ▁into ▁the ▁nuclear ▁gen ome . ▁Despite ▁the ▁met abol ic ▁alter ations ▁and ▁functional ▁adapt ations ▁in ▁the ▁host ▁e uk ary otes ,