Table 1.
The parental genetic distances measured with chloroplast and nuclear DNA, and average pollen fertility of nine wild-collected species (strain ID nos. 1–9) and 43 F1 hybrids (strain ID nos. 10–52).
| Strain ID | Cross designa | Maternal (Populationb) | Paternal (Populationb) | Nc | Nuclear genetic distance | Chloroplast genetic distance | Average fertility (± s.d.) |
| 1 | wild, Clade A | M. pauciflora | 5 | 0 | 0 | 0.872 ± 0.123 | |
| 2 | wild, Clade A | M. koshiensis | 4 | 0 | 0 | 0.798 ± 0.169 | |
| 3 | wild, Clade A | M. furusei var. subramosa | 5 | 0 | 0 | 0.838 ± 0.107 | |
| 4 | wild, Clade B | M. kiusiana | 6 | 0 | 0 | 0.685 ± 0.277 | |
| 5 | wild, Clade B | M. stylosa var. stylosa | 7 | 0 | 0 | 0.813 ± 0.101 | |
| 6 | wild, Clade B | M. stylosa var. makinoi | 8 | 0 | 0 | 0.860 ± 0.122 | |
| 7 | wild, Clade C | M. japonica (Shikoku & Kyushu) | 6 | 0 | 0 | 0.923 ± 0.096 | |
| 8 | wild, Clade C | M. japonica (Honshu) | 4 | 0 | 0 | 0.808 ± 0.123 | |
| 9 | wild, Clade C | M. yoshinagae (Kyushu) | 2 | 0 | 0 | 0.995 ± 0.007 | |
| 10 | WS, Clade A | M. furusei var.furusei (16) | M. furusei var.subramosa (29) | 6 | 0.0087 | 0.0033 | 0.170 ± 0.104 |
| 11 | WS, Clade A | M. furusei var.subramosa (29) | M. furusei var.furusei (16) | 4 | 0.0087 | 0.0033 | 0.205 ± 0.205 |
| 12 | WS, Clade A | M. furusei var.subramosa (18) | M. furusei var.subramosa (38) | 6 | 0.0121 | 0.0061 | 0.103 ± 0.024 |
| 13 | WS, Clade A | M. furusei var.subramosa (38) | M. furusei var.subramosa (18) | 5 | 0.0121 | 0.0061 | 0.028 ± 0.013 |
| 14 | WS, Clade B | M. stylosa var.stylosa (15) | M. stylosa var. makinoi (55) | 12 | 0.0133 | 0.0033 | 0.417 ± 0.217 |
| 15 | WS, Clade C | M. japonica (60) | M. japonica (60) | 3 | 0 | 0 | 0.837 ± 0.015 |
| 16 | WS, Clade C | M. japonica (70) | M. japonica (56) | 9 | 0.0023 | 0.004 | 0.867 ± 0.065 |
| 17 | WS, Clade C | M. japonica (70) | M. japonica (51) | 19 | 0.0023 | 0.0027 | 0.788 ± 0.114 |
| 18 | WS, Clade C | M. yoshinagae (44) | M. yoshinagae (64) | 6 | 0.0217 | 0.0007 | 0.019 ± 0.029 |
| 19 | WS, Clade C | M. japonica (60) | M. japonica (29) | 9 | 0.0364 | 0.0007 | 0.348 ± 0.348 |
| 20 | WS, Clade C | M. japonica (29) | M. japonica (60) | 8 | 0.0364 | 0.0007 | 0.260 ± 0.178 |
| 21 | WS, Clade C | M. japonica (70) | M. japonica (29) | 5 | 0.0378 | 0.0027 | 0.038 ± 0.064 |
| 22 | WS, Clade C | M. japonica (29) | M. japonica (56) | 9 | 0.0385 | 0.0013 | 0.034 ± 0.023 |
| 23 | BS, Clade A | M. furusei var.subramosa (29) | M. pauciflora (29) | 6 | 0.0022 | 0.0014 | 0.303 ± 0.073 |
| 24 | BS, Clade A | M. koshiensis (6) | M. pauciflora (52) | 1 | 0.0087 | 0.002 | 0.140 ± 0 |
| 25 | BS, Clade A | M. furusei var.subramosa (24) | M. pauciflora (24) | 6 | 0.0099 | 0.0034 | 0.343 ± 0.077 |
| 26 | BS, Clade A | M. furusei var.subramosa (19) | M. koshiensis (5) | 7 | 0.011 | 0.0027 | 0.271 ± 0.109 |
| 27 | BS, Clade A | M. acerina (19) | M. furusei var.subramosa (19) | 7 | 0.0122 | 0.0013 | 0.266 ± 0.124 |
| 28 | BS, Clade A | M. furusei var.subramosa (19) | M. acerina (19) | 7 | 0.0122 | 0.0013 | 0.254 ± 0.110 |
| 29 | BS, Clade A | M. furusei var.subramosa (19) | M. acerina (19) | 4 | 0.0122 | 0.0013 | 0.188 ± 0.021 |
| 30 | BS, Clade A | M. acerina (19) | M. furusei var.subramosa (29) | 3 | 0.0156 | 0.004 | 0.270 ± 0.173 |
| 31 | BS, Clade B | M. kiusiana (60) | M. stylosa var. makinoi (71) | 8 | 0.018 | 0.0068 | 0.274 ± 0.128 |
| 32 | BS, Clade B | M. kiusiana (68) | M. doiana (72) | 10 | 0.0203 | 0.0138 | 0.114 ± 0.097 |
| 33 | BS, Clade B | M. stylosa var. makinoi (55) | M. doiana (72) | 12 | 0.025 | 0.0054 | 0.068 ± 0.068 |
| 34 | BS, Clade C | M. yoshinagae (69) | M. japonica (29) | 11 | 0.0214 | 0 | 0.015 ± 0.019 |
| 35 | BS, Clade C | M. japonica (60) | M. yoshinagae (47) | 9 | 0.0301 | 0.0013 | 0.320 ± 0.238 |
| 36 | BS, Clade C | M. formosana (77) | M. japonica (29) | 3 | 0.0316 | 0.0075 | 0 |
| 37 | BS, Clade C | M. yoshinagae (44) | M. formosana (77) | 2 | 0.0316 | 0.0082 | 0.005 ± 0.007 |
| 38 | BS, Clade C | M. japonica (60) | M. yoshinagae (64) | 13 | 0.0354 | 0.0007 | 0.262 ± 0.136 |
| 39 | BC | M. acerina (19) | M. stylosa var. makinoi (55) | 2 | 0.0227 | 0.004 | 0.007 ± 0.007 |
| 40 | BC | M. furusei var.subramosa (38) | M. kiusiana (67) | 3 | 0.0288 | 0.0096 | 0.023 ± 0.040 |
| 41 | BC | M. koshiensis (5) | M. kiusiana (60) | 2 | 0.032 | 0.0075 | 0.030 ± 0.028 |
| 42 | BC | M. kiusiana (68) | M. pauciflora (52) | 6 | 0.0346 | 0.0089 | 0.028 ± 0.026 |
| 43 | BC | M. furusei var.subramosa (24) | M. stylosa var. makinoi (55) | 3 | 0.0347 | 0.0033 | 0.02 |
| 44 | BC | M. pauciflora (52) | M. stylosa var. makinoi (45) | 7 | 0.0371 | 0 | 0.103 ± 0.216 |
| 45 | BC | M. japonica (60) | M. acerina (19) | 4 | 0.0549 | 0.011 | 0 |
| 46 | BC | M. kiusiana (60) | M. japonica (60) | 3 | 0.0646 | 0.0007 | 0 |
| 47 | BC | M. japonica (60) | M. pauciflora (39) | 2 | 0.0672 | 0.0083 | 0 |
| 48 | BC | M. japonica (60) | M. furusei var.subramosa (38) | 3 | 0.0672 | 0.0103 | 0 |
| 49 | BC | M. formosana (77) | M. acerina (19) | 2 | 0.0691 | 0.0054 | 0 |
| 50 | BC | M. formosana (77) | M. stylosa var. makinoi (55) | 3 | 0.072 | 0.0027 | 0 |
| 51 | BC | M. yoshinagae (64) | M. kiusiana (64) | 3 | 0.0747 | 0.0013 | 0.003 ± 0.006 |
| 52 | BC | M. furusei var.subramosa (29) | M. japonica (29) | 2 | 0.0747 | 0.0082 | 0 |
a. Abbrebiations; wild: wild collected, cultivated plants examined for pollen fertility, WS: cross within biological species, BS: cross between species within the clade (A, B, C) defined in Figure 2, BC: cross across the clades.
b. Their geographic origins are shown as a number in parentheses, each of which corresponds to the population ID no. in Additional file 1: Table S1.
c. The number of plant individuals examined for their fertility.