Modeling Sexual Differences of Body Size Variation in Ground Beetles in Geographical Gradients: A Case Study of Pterostichus melanarius (Illiger, 1798) (Coleoptera, Carabidae)

Abstract

The aim of this study was to test the steepness of body size variation in males and females in the widespread ground beetle Pterostichus melanarius in geographical gradients. Beetles were sampled in 15 regions of Europe and Asia, and sampling territories differed 17° in latitude and 121° in longitude. We measured six linear traits in every captured beetle and formed a data set that included 2154 individuals. Body size variation in all traits in general was sawtooth, both in latitude and in longitude gradients. Regression analysis showed slight trends: in the latitude gradient, elytra parameters increased, pronotum length did not change but the width increased, and head parameters decreased. In the longitude gradient, the changes were as follows: elytra length increased, but its width did not change; pronotum length did not change, but its width increased; the head parameters decreased. Thus, we observed the elytra length increase and the head parameters decrease northwards and eastwards. We compared female and male regression curves (trait size on latitude/longitude): p-levels were significant only in four cases out of 12. Thus, we conclude that, in general, there is no evidence for the steepness in trait variation in males compared with females.

Impact of climatic factors on sexual size dimorphism in ground beetle Pterostichus melanarius (Illiger, 1798) (Coleoptera, Carabidae)

“…Head length and width variation followed converse one. More wide investigation showed that in P. melanarius regression slopes in body size were nearly zero both in males and females in latitude gradient, but the real SSD values changed from one region to another significantly (Gordienko et al 2021;Luzyanin et al 2022a).…”

“…We used the same database we have done previously when analyzing P. melanarius (Luzyanin et al 2022a). It included 7677 specimens, measured by six traits: elytra, pronotum and head length, elytra and pronotum width, distance between eyes.…”

“…In this article we used the same data set as we have done previously when analyzing Pterostichus melanarius (Luzyanin et al 2022a). In the latter publication we showed that body size variation in all traits in general was saw-tooth, both in latitude and in longitude gradients.…”

Using museum collections to explore predator–prey relationships in snail‐eating beetles (Carabidae: Cychrini)

“…Across species, we found that, compared to male beetles, female beetles were discovered eating larger snails, although we detected no sex differences in beetle body size. Some carabid species exhibit female‐biased sexual size dimorphism, but other species do not (Luzyanin et al, 2022; Sota et al, 2000). In some ground beetles, stable isotope analyses suggest that males and females differ in their trophic niches (Goncharov et al, 2015), and prey consumption is important for egg production in females (Osawa, 2005).…”

Morphometric Features of the Beetle Acinopus (Acinopus) Laevigatus Menetries, 1832 (Coleoptera, Carabidae) in the Mountain Ecosystems of Uzbekistan

“…Two populations of Nebria kraatteri in the Sila Mountains in Italy showed significant differences in many morphometric parameters (Talarico et al, 2020). An increase in the length of the elytra and a decrease in the parameters of the head in Pterostichus melanarius in the northern and eastern directions were established (Luzyanin et al, 2022).…”