Table 1.
Differences between taxonomic criteria in the proportion of splits and lumps in taxonomic studies of birds, 1950–2007.
| criterion | sample | lump | split |
|---|---|---|---|
| all hypotheses | 747 | 299 (40.0%) | 448 (60.0%) |
| reproductive isolation | 232 | 77 (33.2%) | 155 (66.8%) |
| diagnosability | 452 | 100 (22.1%) | 352 (77.9%) |
| degree of difference | 216 | 102 (47.2%) | 114 (52.8%) |
| adaptive zone | 70 | 11 (15.7%) | 59 (84.3%) |
| monophyly | 46 | 5 (10.9%) | 41 (89.1%) |
| exclusive coalescence | 19 | 1 (5.3%) | 18 (94.7%) |
| PSC-based criteria onlya | 214 | 50 (23.4%) | 164 (76.6%) |
| non-PSC-based criteria onlyb | 165 | 113 (68.5%) | 52 (31.5%) |
| both PSC and non-PSC criteria | 264 | 53 (20.1%) | 211 (79.9%) |
| taxonomic rationale not stated | 104 | 83 (79.8%) | 21 (20.2%) |
aDiagnosability, monophyly, exclusive coalescence.
bDegree of difference, adaptive zone, reproductive isolation.