However, if this idea is correct, maternal transmission of organelle DNA should not occur in
isogamous organisms where there are no size differences between male and female gametes.
However, in Ulvophyceae the furrowing type of somatic cytokinesis, the cruciate, flagellar roots of the motile cell, and the fact that not only male but also female gametes of Ulva are motile (the gametes being
isogamous or anisogamous) would all but preclude the direct involvement of ulvophytes in land-plant origins (cf.
For the inbreeding effective size, however, they considered six specific cases: case 1:
isogamous monoecious diploids with selfing permitted, or case 2: excluded; case 3: male and female gametes distinguished with selfing permitted, or case 4: excluded; and case 5: separate sexes with progeny identified as to sex, or case 6: not identified.