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11 January 2023 Female and male plumage brightness is positively correlated among populations of the dichromatic Variable Seedeater
Diego Ocampo, Gilbert Barrantes, J. Albert C. Uy
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Because studies of plumage coloration often focus on highly elaborate and conspicuous males, little is known about the factors driving the evolution of drab plumage in females of dichromatic species. We explored variation in the color properties of drab female plumage across subspecies of the Variable Seedeater (Sporophila corvina) and found a correlation between plumage brightness of male and female plumage patches. This correlation is consistent with the hypothesis that differences in plumage brightness among females result, at least partially, from a genetic correlation or shared developmental pathway with the more conspicuous male plumage traits that are shaped by sexual selection. Furthermore, we modeled the perception of female plumage using the avian visual system and found that most of the variation in color among females is undetectable by birds; therefore, it is unlikely for such variation to have evolved via direct sexual selection as a signal for recognition or assortative mating. Together, these results suggest that variation in S. corvina female color result from non-adaptive processes. However, we found a reduced variation on color of dorsal patches compared with that of ventral patches among females, which could be explained by natural selection on crypsis, reducing the variation on dorsal patches. Finally, we found little differences in plumage color between adult females and juveniles, which suggest selection for juveniles to resemble adult females possibly to reduce aggression from adult males. Additional within-population studies and behavioral experiments are needed to discern the evolutionary factors driving variation on S. corvina female color and its function.


  • We evaluated color variation among females of the Variable Seedeater, an avian species in which females show an overall brown-yellowish and relatively uniform coloration among populations, contrary to the highly variable and contrasting black and white males.

  • Among adult females, color variation is unlikely to facilitate subspecies recognition and assortative mating.

  • The variation in plumage brightness of female ventral patches may result from more relaxed selection compared to dorsal patches and from a shared feather developmental pathway with sexually selected male patches.

  • Adult females did not differ from young individuals, which may allow young males accessing mates, roosting sites, and food, while avoiding aggression from older territorial males.

Debido a que los estudios de coloración del plumaje a menudo se centran en machos con plumajes elaborados y llamativos, sabemos poco sobre los factores que impulsan la evolución del plumaje monótono en las hembras de especies dicromáticas. Exploramos la variación en las propiedades del color del plumaje en hembras de Sporophila corvina y encontramos una correlación entre el brillo de los parches del plumaje de machos y hembras. Esta correlación es consistente con la hipótesis de que las diferencias en el brillo del plumaje en hembras son resultado, al menos parcialmente, de una correlación genética o una vía de desarrollo compartida con los rasgos más conspicuos del plumaje de machos, que están influenciados por selección sexual. Además, modelamos la percepción del plumaje de las hembras usando el sistema visual de las aves y descubrimos que, en su mayoría, la variación del color entre hembras es indetectable por las aves; por lo tanto, es poco probable que haya evolucionado a través de selección sexual como señal de reconocimiento o apareamiento selectivo. Estos resultados sugieren que la variación en el color de las hembras de S. corvina se debe a procesos no adaptativos. Sin embargo, encontramos una menor variación del color en los parches dorsales en comparación con los ventrales entre las hembras, lo que podría explicarse por selección natural reduciendo la variación en los parches dorsales. Finalmente, encontramos poca diferencia en la coloración entre las hembras adultas y los juveniles, lo cual es consistente con selección en los juveniles por parecerse a hembras adultas, posiblemente para reducir la agresión de los machos adultos. Más estudios dentro de la población y experimentos de comportamiento son necesarios para discernir los factores evolutivos que impulsan la variación del color de las hembras de S. corvina y su función.

Diego Ocampo, Gilbert Barrantes, and J. Albert C. Uy "Female and male plumage brightness is positively correlated among populations of the dichromatic Variable Seedeater," Ornithology 140(2), 1-13, (11 January 2023).
Received: 23 October 2022; Accepted: 4 January 2023; Published: 11 January 2023
Brillo del plumaje
Color de hembras
color del plumaje
dichromatic species
drab plumage
Especies dicromáticas
female color
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