Sexual size dimorphism variation in altitude gradients in ground beetles (Coleoptera, Carabidae)

Abstract

In this study, we verified the theory about the greatest steepness in body size variation in insects males compared with females in altitude gradients. As the model, ground beetles took as the appreciated bioindicators. We sampled three species of carabids at two regions: Carabus odoratus and Pterostihusmontanus were sampled at four elevations at Barguzin Ridge (N 54° 20’; E 109° 30’, Russia) and Carabus exaratus – at three elevations in mountainous terrain in Chechnya Republic (42088’N 46044’E Russia). We measured more than 1000 individuals by six linear traits and construct regression models of females’ and males’ size variation along elevation gradients. The regression slopes in the majority of the overwhelming case (14 models out of 18) were sex-biased. In P. montanus elytra length variation and C. exaratus traits width variation, the slopes differed in males and females only: In the first case, trait value in females significantly increased and in the second traits values varied in opposite directions. Therefore, we did not find evidence of greater steepness in male traits variation in ground beetles.