https://phaidra.vetmeduni.ac.at/o:4781 Allometry, sexual dimorphism, and sexual trait elaboration in the birds-of-paradise MacGillavry, Thomas Thomas MacGillavry 0000-0002-2298-6670 University of Veterinary Medicine Vienna Fusani, Leonida Leonida Fusani 0000-0001-8900-796X University of Veterinary Medicine Vienna Toyama, Ken S. Ken S. Toyama 0000-0002-8331-4894 Oxford University Press journal article open access eng Rensch's rule (RR) is a widespread macroevolutionary pattern describing a positive association between male-biased dimorphism and species size. Applied to sexual size dimorphism, RR is often associated with sexual selection, as larger body sizes may benefit males in competition and courtship. Moreover, the presence of RR in sexual traits further indicates that males reap relative performance benefits beyond large body size alone. Here we describe patterns of elaboration, variation, and sexual dimorphism in tail length in the birds-of-paradise (Aves: Paradisaeidae), which exhibit an extreme diversity in tail lengths, ranging from short-tailed species to the longest-tailed passeriform birds. We found that body size followed RR in polygynous, but not monogamous species, in accordance with the sexual selection hypothesis. However, we found no evidence of RR in tail length, indicating similar evolutionary allometries between males and females. Evolutionary allometries of male and female traits were both strongly positive among long-tailed species, suggesting that the lack of RR results from phenotypic correlations between the sexes, rather than constraints on ornament exaggeration. Our study represents the first integrative test of RR in an ornamental morphological trait and evidences how different aspects of dimorphism interact in a group with a hyperdiverse courtship trait. Online Version of Record before inclusion in an issue http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:4781/download 10.1093/evolut/qpaf263 https://phaidra.vetmeduni.ac.at/o:605 application/pdf Evolution issn:0014-3820 VoR Evolution 1.75 MB 2025