  Although it is fairly established that Gravitational Instability (GI) should
occur in the early phases of the evolution of a protoplanetary disk, the fate
of the clumps resulting from disk fragmentation and their role in planet
formation is still unclear. In the present study we investigate
semi-analytically their evolution following the contraction of a synthetic
population of clumps with varied initial structure and orbits coupled with the
surrounding disk and the central star. Our model is based on recently published
state-of-the-art 3D collapse simulations of clumps with varied thermodynamics.
Various evolutionary mechanisms are taken into account, and their effect is
explored both individually and in combination with others: migration and tidal
disruption, mass accretion, gap opening and disk viscosity. It is found that,
in general, at least 50% of the initial clumps survive tides, leaving behind
potential gas giant progenitors after ~10^5 yr of evolution in the disk. The
rest might be either disrupted or produce super-Earths and other low mass
planets provided that a solid core can be assembled on a sufficiently short
timescale, a possibility that we do not address in this paper. Extrapolating to
million year timescales, all our surviving protoplanets would lead to close-in
gas giants. This outcome might in part reflect the limitations of the migration
model adopted, and is reminiscent of the analogous result found in
core-accretion models in absence of fine-tuning of the migration rate. Yet it
suggests that a significant fraction of the clumps formed by gravitational
instability could be the precursors of Hot Jupiters.
