The nature of allometry in an exaggerated trait: The postocular flange in Platyneuromus Weele Insecta: MegalopteraReport as inadecuate




The nature of allometry in an exaggerated trait: The postocular flange in Platyneuromus Weele Insecta: Megaloptera - Download this document for free, or read online. Document in PDF available to download.

The origin and function of exaggerated traits exhibited by a great number of species with sexual dimorphism remain largely unexplored. The usual model considered as the evolutionary mechanism for the development of these structures is sexual selection. The nature of growth of the postocular flange POF in three species of the dobsonfly genus Platyneuromus Megaloptera, Corydalidae, Corydalinae is analyzed to explore sexual size dimorphism and allometric scaling. Results involve positive allometry of POF in males of two species, and negative allometry in males of one species, in general with a female-biased sexual dimorphism. We suggest an ancestral condition of dual incipient ornamentation in Platyneuromus, with a subsequent departure of size and shape of POF in males, triggered by sexual selection. Different sexual selection intensities may explain the parallel or divergent growth of POF within the scheme of dual ornamentation. Empirical behavioral data as well as a phylogenetic framework are necessary to clarify possible causes of phenotypic development, time of origin, and evolution of the POF.



Author: Andrés Ramírez-Ponce, Gabriela Garfias-Lozano, Atilano Contreras-Ramos

Source: http://plos.srce.hr/



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