  Radio-loud active galactic nuclei (RLAGN) play an important role in the
evolution of galaxies through the effects on their environment. The two major
morphological classes are core-bright (FRI) and edge-bright (FRII) sources.
With the LOw-Frequency ARray (LOFAR) we compare the FRI and FRII evolution down
to lower flux densities and with larger samples than before with the aim to
examine the cosmic space density evolution for FRIs and FRIIs by analyzing
their space density evolution between L_150~10^24.5 W/Hz and L_150~10^28.5 W/Hz
and up to z=2.5. We construct radio luminosity functions (RLFs) from FRI and
FRII catalogues based on recent data from LOFAR at 150MHz to study the space
densities as a function of radio luminosity and redshift. To partly correct for
selection biases and completeness, we simulate how sources appear at a range of
redshifts. We report a space density enhancement from low to high redshift for
FRI and FRII sources brighter than L_150~10^27 W/Hz. This is possibly related
to the higher gas availability in the earlier denser universe. The constant
FRI/FRII space density ratio evolution as a function of radio luminosity and
redshift in our results suggests that the jet-disruption of FRIs might be
primarily caused by events occurring on scales within the host galaxy, rather
than being driven by changes in the overall large-scale environment. Remaining
selection biases in our results also highlight the need to resolve more sources
at angular scales below 40 arcsec and therefore strengthens the motivation for
the further development and automation of the calibration and imaging pipeline
of LOFAR data to produce images at sub-arcsecond resolution.
