Arguments in favor of the Two Source Hypothesis can be found in the essay on The Existence of Q.
For example, in Luke , Luke's "give alms" may well be Lk R (Lukan redaction), reflecting Luke's concern for almsgiving.
A direct literary connection between Mark and Q must be regarded as improbable.
The text complexes they share point rather to independent access of each to old Jesus-traditions, but contacts between the two streams of tradition at the pre-redactional level are not to be excluded.
Thus the conditions in which the Sayings Source originated included both continuity with the beginnings and with the developing congregational structures across the region. Mark wrote his story of Jesus some time after the war and shortly after Q had been revised with the Q3 additions. Q's characterization of Jesus as the all-knowing one could be used to enhance his authority as a self-referential speaker in the pronouncement stories Mark already had from his own community.
(2) The Sayings Source presupposes persection of the young congregations by Palestinian Jews (cf. The notion of Jesus as the son of God could be used to create mystique, divide the house on the question of Jesus' true identity, and develop narrative anticipation, the device scholars call Mark's "messianic secret." The instruction for the workers in the harvest could be turned into a mission charge, and the theme of discipleship could be combined and given narrative profile by introducing a few disciples into the story.