  We study the dynamical evolution of Jupiter and Saturn embedded in a gaseous,
solar-nebula-type disc by means of hydrodynamics simulations with the FARGO2D1D
code. We study the evolution for different initial separations of the planets'
orbits, Delta a_SJ , to investigate whether they become captured in mean motion
resonance (MMR) and the direction of the subsequent migration of the planet
(inward or outward). We also provide an assessment of the planet's orbital
dynamics at different epochs of Saturn's growth. We find that the evolution of
initially compact orbital configurations is dependent on the value of Delta
a_SJ . This implies that an evolution as that proposed in the Grand Tack model
depends on the precise initial orbits of Jupiter and Saturn and on the
timescales for their formation. Capture in the 1:2 MMR and inward or (nearly)
stalled migration are highly favoured. Within its limits, our work suggests
that the reversed migration, associated with the resonance capture of Jupiter
and Saturn, may be a low probability evolutionary scenario, so that other
planetary systems with giant planets are not expected to have experienced a
Grand Tack-like evolutionary path.
