Date of this Version
The confusing leading article of the 1961 Auk calls for comment. Despite his title, "Evolutionary Relationships among the North American Mallards," the author discusses primarily geographic distributions, population sizes, egg-white proteins( !), and certain behavioral patterns. Maps are based on ". . . the literature, personal communications, and the major United States collections," " . and from additional sight and specimen records available to me"; yet only two museums other than Cornell University are mentioned in the acknowledgments. These maps show many records of platyrhynchos far to the south; sometimes (Figure 1) the reader must search hard for any hint that these are not breeding localities. The section "Estimation of Gene Pools and Hybridization Incidence" discusses only a part of the area of present overlap of breeding Anas p. platyrhynchos and rubripes; these population estimates are worthless from most standpoints, since all were made in fall and winter, thus consisting of birds from very diverse areas, some of them outside of the zone of overlap. The section "Materials and Methods" tells us neither the source of the specimens examined nor what measures, if any, were taken to assure the purity of their strain. Instead, we read a long account of the measurement of general plumage darkness, a matter never considered of primary importance in this group by taxonomists. As was therefore predictable, this proves to have little real value. The taxonomically useful characters are mentioned by Johnsgard only in summarizing the literature, after which he ignores all of them except the secondary coverts! He merely states that ". . . supposed differences in speculum coloration . . . and the degree of streaking on the throat . . . were not considered of major importance for study." Under "Evolutionary Implications" we read that sexually nondimorphic populations arose by the same mutation at three different times and places; whereas actually a consideration of the entire mallard group, including the Pacific island forms, points strengly in the opposite direction, i.e., the acquiring once in a nondimorphic species of sexual dimorphism, a character that is still spreading out geographically.