Table 3. Chromosome number variation in individually karyotyped specimens.
| Line/culture/ field collection | n | 'normal' karyotype n (%) | plus one large metacentric n (%) | plus two large metacentrics n (%) | 'abnormal' karyotypes n (%) | X2 | DF | P |
|---|---|---|---|---|---|---|---|---|
| (a) Inbred lines and outbred cultures of M. lignano | ||||||||
| Inbred lines | ||||||||
| DV1 | 134 | 16 (11.9%) | 77 (57.5%) | 36 (26.9%) | 5 (3.7%) | |||
| (observed)* | 129 | 16 (12.4%) | 77 (59.7%) | 36 (27.9%) | - | 6.43 | 1 | 0.011 |
| (expected)* | (17.8%) | (48.8%) | (33.4%) | - | ||||
| HUB1 | 137 | 18 (13.1%) | 72 (52.6%) | 42 (30.7%) | 5 (3.6%) | |||
| (observed)* | 132 | 18 (13.6%) | 72 (54.5%) | 42 (31.4%) | - | 2.17 | 1 | 0.141 |
| (expected)* | (16.7%) | (48.3%) | (34.9%) | - | ||||
| Outbred cultures | ||||||||
| LS1 | 285 | 276 (96.8%) | 5 (1.8%) | - | 4 (1.4%) | |||
| LS2 | 61 | 61 (100%) | - | - | - | |||
| LS3 | 50 | 23 (46%) | 6 (12%) | 17 (34%) | 4 (8%) | |||
| IBK2 | 50 | 44 (88%) | 1 (2%) | - | 5 (10%) | |||
| (b) Freshly field-collected specimens | ||||||||
| M. lignano | 122 | 120 (98.4%) | 1 (0.8%) | 1 (0.8%) | ||||
| Macrostomum sp. 8 | 22 | 18 (81.8%) | 2 (9.1%) | - | 2 (9.1%) | |||
| (c) Cultures of other Macrostomum species | ||||||||
| M. spirale (2n = 6) | 97 | 91 (100%) | - | - | - | |||
| M. hystrix (2n = 6) | 10 | 10 (100%) | - | - | - | |||
(a) inbred lines and outbred cultures of M. lignano
(b) freshly field-collected specimens of M. lignano and Macrostomum sp. 8, and
(c) cultures of other Macrostomum species (M. spirale and M. hystrix).
The 'normal' karyotype is 2n = 8 in M. lignano (two large and six small metacentrics), 2n = 10 in Macrostomum sp. 8 (four large and six small metacentrics), 2n = 6 in M. spirale (six metacentrics), and 2n = 6 in M. hystrix (two metacentrics and four submetacentrics). For both the DV1 and HUB1 lines we further provide a test for deviations from the expected karyotype frequencies (for rationale of test see main text).
Note that the asterisks (*) indicate that we have excluded the 'abnormal' karyotypes for these calculations.
Based on the observed karyotype frequencies among the analyzed individuals the expected frequencies for n = 4 and n = 5 gametes are p = 0.422 and q = 0.578 for DV1 and p = 0.409 and q = 0.591 for HUB1, respectively, permitting to calculate the expected karyotype frequencies (i.e. p2, 2pq, and q2 for the 2n = 8, 2n = 9, and 2n = 10 karyotypes, respectively).