Variation and population structure of the tourmaline sunangel, Heliangelus exortis exortis (Aves, Trochilidae). American Museum novitates ; no. 2811

14 p. : ill., map ; 26 cm.Includes bibliographical references (p. 13-14)."The nominate form of the polytypic Andean hummingbird the tourmaline sunangel, Heliangelus exortis exortis, exhibits dramatic variation in a female polychromatism of throat iridescence within and among populations that has not heretofore been appreciated. An analysis of the geographic population structure of samples referable to H. e. exortis was conducted to determine the biological status and historical process of differentiation of polychromatically differentiated samples. Geographic variation in additional color and six mensural characters is discordant within and between the sexes. The polychromatism shows both regular and mosaic patterns of geographic variation. Geographic patterns of variability in the polychromatism do not appear to result from increased variability in putative zones of hybridization between differentiated populations. No character breaks that might indicate noninterbreeding parapatric forms were noted. It is concluded that H. e. exortis comprises a single biological entity and taxon within the polytypic H. exortis complex. The evolutionary origins of the complex pattern of geographic variation in H. e. exortis are discussed. I suggest that biological attributes, in addition to potential geographic barriers, are necessary for a full understanding of the geographic differentiation seen in H. e. exortis"--P. [1]

Systematics and geographic variation in the golden-breasted puffleg Eriocnemis mosquera (Aves, Trochilidae). American Museum novitates ; ; no. 2913.

8 p. : ill., 1 map ; 26 cm.Bibliography: p. 7-8

Asymmetrical expression of transsexual phenotypes in hummingbirds.

I present evidence for asymmetry in the expression of transsexual traits in adult hummingbirds. Among females, individuals with male-like plumage are common and define a continuous range of variation. Among males, individuals with female-like plumage are rare and define discontinuous plumage morphs. Quantitative characters also distinguish transsexuals from other members of their sex, but the characters involved differ for male-like females (bill length) and female-like males (bill, wing and tail length). Gonadal development is correlated with transsexuality only in males; female-like males have significantly smaller testes than male-like males. Both sexes demonstrate a significant negative association between plumage brightness and bill length. This association suggests an ecological basis for transsexuality because differences in plumage and bill morphology are associated with differences in foraging behaviour within and between hummingbird species. Morphological differences between transsexuals and non-transsexuals imply that plumage sexual dimorphism is more likely to evolve through changes in the frequency of female, rather than male, transsexual variants