Testosterone and melanin-based black plumage coloration: a comparative study

  • Veronika Bókony
  • László Zsolt Garamszegi
  • Katharina Hirschenhauser
  • András Liker
Original Paper


Despite the functional significance of melanin-based plumage coloration in social and sexual signaling, the mechanisms controlling its information content are poorly understood. The T-regulation hypothesis proposes that melanin ornaments signal competitive abilities via the effects of testosterone (T) mediating both melanization and sexual/aggressive behaviors. Using the phylogenetic comparative approach, we tested whether frontal black melanization is associated with elevated T around the time of breeding plumage development across all bird species with available T-data. We found a context-dependent relationship between melanization and T, varying with the type of ornamentation (patchy or full-black) and with the presumed taxonomic distribution of the hormonal control of plumage dichromatism. Within two taxa in which male plumage development is assumed androgen-dependent (Charadriiformes, Corvida), evolutionary increases in male melanization, and melanin dichromatism correlated with increases in T in most analyses but not within the basal lineage (ratites, Galloanseriformes) with androgen-independent male plumage. Among Passeroidea with presumably genetically or luteinizing-hormone-based male plumage, melanization and its dichromatism correlated with T only in species with <100% frontal melanization. These results were robust as we controlled for several confounding variables such as mating and parental behaviors. This study is the first to test and support the T-regulation hypothesis interspecifically, suggesting that among-species differences in melanization may have evolved in response to differences in circulating T in certain avian taxa. Our results imply that the extent of black ornamentation may serve as an honest indicator of male competitiveness in those species that evolved an appropriate hormonal basis (T dependence) for color production.


Androgens Hormonal control Melanin ornaments Sexual selection Status signals 

Supplementary material

265_2008_551_MOESM1_ESM.doc (30 kb)
S1Reliability of species-specific T measures used in the study (DOC 31 kb)
265_2008_551_MOESM2_ESM.doc (388 kb)
S2Data on melanization, T levels, and confounding variables used in the analyses (DOC 397 kb)
265_2008_551_MOESM3_ESM.doc (422 kb)
S3Topology and references of the composite phylogenies used in the analyses (DOC 431 KB)
265_2008_551_MOESM4_ESM.doc (69 kb)
S4Full multivariate phylogenetic GLS models of male melanization and melanin dichromatism in relation to T levels and sexual and paternal behaviors (DOC 70 kb)

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Veronika Bókony
    • 1
  • László Zsolt Garamszegi
    • 2
  • Katharina Hirschenhauser
    • 3
  • András Liker
    • 4
  1. 1.Department of EcologySzent István UniversityBudapestHungary
  2. 2.Department of BiologyUniversity of Antwerp, U.A.WilrijkBelgium
  3. 3.Konrad Lorenz Research StationGrünauAustria
  4. 4.Department of LimnologyUniversity of PannoniaVeszprémHungary

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