Selles had guided Studying to sixth in League One regardless of their off-field issues when he left for East Yorkshire on 6 December.
Predecessor Walter had been relieved of his duties the earlier week after a run of 9 matches and not using a win.
Selles claimed his first win as Tigers boss with a 2-1 residence victory over Swansea on 21 December to finish a winless run of 13 matches.
Though they claimed notable outcomes away from residence beneath Selles, together with wins at promotion-chasing Sheffield United and Sunderland, they discovered residence wins extremely onerous to return by and ended the season with the worst residence file within the division.
Defeats on the MKM Stadium by fellow strugglers Luton and Derby meant they went into the ultimate sport of the season within the Championship relegation zone.
Different fixtures meant a win would assure their survival and, though they have been pegged again at Fratton Park after Matt Crooks had given them the lead, a degree proved to be sufficient to maintain them up on purpose distinction.
After the match Selles advised BBC Radio Humberside: “Everybody within the membership managed troublesome moments and it has been a troublesome season for everybody and we deserved to remain within the division.
“We had a workforce that was all-time low and to realize the goal this season with all of the accidents and every little thing else is simply large.
“Now it is over and we crossed the road, we will relaxation somewhat bit and I advised the gamers that we’ll bear in mind today for years to return.”
