title: Sexual shape and size dimorphism in carabid beetles of the genus Ceroglossus: is geometric body size similar between sexes due to sex ratio?
abstract: Insects in many species vary greatly in the expression of secondary sexual traits, resulting in sexual dimorphism, which has been proposed to be a consequence of differences in sexual selection. In this study, we analyze the occurrence of sexual shape dimorphism and the correlation between geometric body size in males and females and sex ratio in the genus Ceroglossus (Coleoptera: Carabidae) using geometric morphometrics and randomization analysis. Our results show a positive relationship between the centroid size of males and females and sex ratio. However, we also observed a trend to maintain a "similar" body shape between sexes and species due to characteristics associated with sexual selection of the group in which the scarcity of outstanding morphological characters does not restrict reproduction capacity. The trend in sexual proportions was found to be near 1:1 for the eight species. We propose that the observed differences between sexes associated with the sex ratio are due to an energy cost caused by sexual selection; nevertheless, since proportions are similar for all the species, it is really not relevant to generate more conspicuous structures for a stronger male-male competence.
authors.affiliation: Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK. hugo.benitez@postgrad.manchester.ac.uk
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Benítez
authors.forename: Maria-José
authors.initials: MJ
authors.lastname: Sanzana
authors.forename: Viviane
authors.initials: V
authors.lastname: Jerez
authors.forename: Luis E
authors.initials: LE
authors.lastname: Parra
authors.forename: Cristián E
authors.initials: CE
authors.lastname: Hernández
authors.forename: Cristian B
authors.initials: CB
authors.lastname: Canales-Aguirre
mesh_terms: D000818:Animals; D049628:Body Size; D001517:Coleoptera / Q000502:physiology*; D005260:Female; D008297:Male; D012744:Sex Ratio