Wales will be without several key players for the autumn, with Cardiff pair Josh Adams and Taulupe Faletau both expected to miss all three Tests.
Exeter lock Dafydd Jenkins and Dragons hooker Elliot Dee also miss out through injury, while Dragons number eight Aaron Wainwright is in a race to be fit after recovering from a hamstring injury.
Scarlets scrum-half Gareth Davies is unavailable after announcing his international retirement.
“Firstly, we’re looking for good men, men who want to be part of a team, who are prepared to go to the well and dig deep,” said Gatland.
“A lot of players, particularly the younger ones, don’t always know the limits of what they can do, and how hard and far they can push themselves at the highest level.
“For a number of them they realise pretty quickly that the step up to international rugby is massive in terms of pace, physicality and intensity. I’ve always said as a coach that you can’t coach ‘experience’ – it has to be learned just by being out there and playing.”
