New Zealand born Leafa, who has signed a one year deal, spent the 2005 season with Leigh in Super League when he was the Centurion's only ever present. Last season he was playing for Wynnum-Manly in the Wizard Queensland competition, before returning to the UK mid-season to join Whitehaven, who were very keen to keep him for 2007, in their NL1 campaign.
Tigers Football Manager Mick Robinson: "Mark is a strong running back rower who plays in a similar style to Willie Manu, who he has played alongside in Australia. He is a non-quota player who proved his durability at Leigh and I understand that the respect he gained at Whitehaven this season was such that their coach wanted to retain him and his team mates urged the Board to keep him at the Recreation Ground."
A very versatile player, 23-year-old Barker can play in the back row or stand off and was unlucky to be released by the Rovers after their promotion to Super League. A former captain of the Rhinos Academy, Barker has also won England honours at that level. He has signed a one-year deal with the Tigers.
Club spokesman David Smart said: "Dwayne is a very versatile player who can operate equally well both the backs and the back-line. He went well for Hull KR in their promotion campaign and it was something of a surprise when he became available. However we were very pleased to take advantage of the opportunity and he gives us plenty of options and is very keen to emulate his achievements this year and help take the Tigers back into the top flight.
Dwayne: "I'm really looking forward to joining the Tigers. It's a new start for me and after I had spoken to Terry (Matterson) I snapped up the opportunity. The Tigers are local for me; they are a good club and one that I have wanted to join for some time. They have made some good signings and I'm confident that we will go really well next year."