Fig. 23. Two additional views of the model shown in fig. 22 illustrating serological relationships among fringillid and related birds. For further explanation, see text, pp.[ 193-194].
| Genera | Pi | . . . . | Piranga | |||
| C | . . . . | Carpodacus | Po | . . . . | Poephila | |
| E | . . . . | Estrilda | R | . . . . | Richmondena | |
| J | . . . . | Junco | Sn | . . . . | Spinus | |
| M | . . . . | Molothrus | Sz | . . . . | Spiza | |
| Pa | . . . . | Passer | Z | . . . . | Zonotrichia | |
Within the richmondenine-emberizine-thraupid assemblage, Junco and Zonotrichia constitute a sub-group apart from the others. Piranga and Richmondena show close serological correspondence. The present taxonomic position of Spiza in the Richmondeninae, which has been questioned by Beecher (1951a:431; 1953:309), is corroborated at least insofar as the serological evidence is concerned. Certainly, serological correspondence of Spiza with the richmondenine-emberizine-thraupid assemblage is greater than with any other group of birds tested.
It is obvious that the serological affinities of the carduelines do not lie with the richmondenines, emberizines, or thraupids. The carduelines show greater serological correspondence with the estrildines than they do with any of the other groups tested. Further serological investigation involving other species, however, is necessary before the nearest relatives of the carduelines can be determined with certainty.
The two estrildines tested (Estrilda and Poephila) show close serological relationship. Their nearest relatives, serologically, seem to be the carduelines. The classification (Wetmore, 1951) that places Passer in the same family with the estrildines is not upheld by the serological data available. Passer is not, serologically, closely related to any of the birds tested. It is of interest that Beecher (1953:303-305), on the basis of jaw musculature, places Passer and the estrildines in separate families (Ploceidae and Estrildidae, respectively).
Molothrus shows greater serological correspondence to the richmondenine-emberizine-thraupid assemblage than to any of the other birds tested. It is definitely set apart from this group, however, and its position, serologically, is compatible with that based on evidence from other sources.
There seems to be but little argument among ornithologists that icterids, fringillids, and ploceids constitute families which are distinct from one another. If, then, the serological differences between Molothrus (Icteridae) and Richmondena (Fringillidae), between Molothrus and Zonotrichia (Fringillidae), and between Richmondena and Poephila (Ploceidae) are indicative of family differences, there are four families represented by the birds involved. Molothrus represents one family; Piranga, Richmondena, Spiza, Junco, and Zonotrichia, a second; Estrilda, Poephila, Carpodacus, and Spinus, a third; and Passer, a fourth.