CLIMATIC FACTORS CAN DIFFERENTLY AFFECT BODY SIZE IN CLOSELY RELATED SPECIES (THE CASE STUDY IN GROUND BEETLES)

Abstract

The study of body size variation in the altitudinal gradient showed the presence of shifts in the morphometric characteristics of ground beetle populations under the influence of bioclimatic factors. Ground beetles were collected on the Barguzinsky Ridge (Russia, Buryatia) in eight characteristic biotopes in four high-altitude sections: on the coast of Lake Baikal, low, middle and high mountains (458-1667 m above sea level). At each site in 2004–2017, we carried out a quantitative account of ground beetles and recorded the main climatic parameters using thermochrons, sedimentary cylinders, soil thermometers, and a snow gauge. We took two common species – Carabus odoratus and Pterostichus montanus (2200 specimens) for morphometric analysis. The six features of the body organs – the length and width of the elytra, the length and width of the pronotum, and the length of the head and distance between the eyes were measured. Using linear modeling, we investigated how climatic variables affected body size in the studied species. Comparing the reaction of the two species to hydroclimatic parameters, we noted that the reaction was directly opposite to temperature indicators, and the similar to factors that depend on humidity. The higher was the soil temperature at a 5 cm depth, the greater was the length of the elytra, pronotum, and head in C. odoratus, but the same characters were smaller in P. montanus. High population density led to body size decrease in C. odoratus, but P. montanus responded in lesser degree. By genus, C. odoratus turned out to be more sensitive to changes in bioclimatic factors.