  The Kepler spacecraft is providing photometric time series with
micro-magnitude precision for thousands of variable stars. The continuous
time-series of unprecedented time span open up opportunities to study the
pulsational variability in much more detail than was previously possible from
the ground. We present a first general characterization of the variability of
A-F type stars as observed in the Kepler light curves of a sample of 750
candidate A-F type stars, and investigate the relation between gamma Doradus,
delta Scuti, and hybrid stars. Our results imply an investigation of pulsation
mechanisms to supplement the kappa mechanism and convective blocking effect to
drive hybrid pulsations and suggest a revision of the current observational
instability strips of delta Scuti and gamma Doradus stars if the currently
available values of effective temperature and surface gravity will be
confirmed.
