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Quantifying elevational effect on the geometric body shape of Russian beetle Carabus exaratus (Coleoptera: Carabidae)

Abstract:

The study of phenotypic changes in organisms at different organizational levels (population, community, and ecosystem) in combination with genetic and genomic tools have helped researchers to understand how microevolutionary processes may lead to adaptation. Insects have been used in many studies as change bioindicators in the ecosystem and they have been the focus of many genetic, ecological and morphological studies. In the following research, we studied how an endemic beetle species Carabus exaratus Quensel, modified its phenotype in response to the altitudinal clines in the Russian North Caucasus. Altitude plays an important role in the size and shape of many species. Shape changes were studied across three altitudinal gradients from 90 to 1018 m.a.s.l using geometric morphometric tools in order to identify if there are specialized phenotypes to altitude. Our results showed a principal relationship between centroid size and altitude where specimens from higher mountains were bigger than the other two groups, also an independent body shape was noted between the three populations where organisms of the mountain had a bigger and convex shape in comparison with smaller and oval shape from the foothill and plain. These results were analyzed using geometric morphometrics for the first time on endemic beetles from the Russian North Caucasus, helping us to understand morphological changes. They suggest that these changes may depend on climatic conditions at high altitudes, where univoltine and bivoltine reproductive behaviors were noticed, implying larger and shorter breeds which are directly reflected on morphological changes. More studies are needed to identify the ontogenetic pattern that affects the body shape in these environments.