Does the geometric and linear morphometry of the brain reflect the divergence in the "guentheri" group (Arvicolinae, Sumeriomys)?

The purpose of this work is to investigate the divergence of the brain’ size and shape of three vole's taxa of “guentheri” group using geometric and linear morphometric analysis. The obtained data show that the sex factor does not affect the brain's linear parameters and shape of the studied taxa that indicates a weak effect of the sexual selection on morphological adaptation and variability of the brain structure. The linear measurements of the investigated taxa differ significantly by all signs (24 parameters). The obtained data indicate that the divergence of Microtus guentheri and M. hartingi is the most significant (92%) that obviously is associated with ancient isolation of this species by Anatolian Diagonal. The differences between the two subspecies (M. hartingi hartingi and M. h. lydius) are much smaller — 63%. It should be noted that the vole of the Strandzha Mountain — M. h. strandzensis differs from the M. h. hartingi and M. h. lydius significantly more — 82 and 75%, respectively. These differences may reflect the history of the investigation of voles from Anatolia to Europe. Geometric deformities of the brain of all taxa are found. Analysis of canonical variations showed that all three taxa differ significantly, both laterally and dorsally. Comparison of taxa lateral views showed that M. h. lydius brain is more flatten than M. h. hartingi, but M. guentheri has a broader brain and a smoother outer olfactory tract as well as smaller olfactory bulbs. By dorsal view, deformation of M. guentheri brain at the attachment sites of the cerebellum hemisphere to the cerebral hemisphere is observed, while the cerebellum worm of M. h. lydius is more flattened. The factors affecting the diversity of brain complexity could include allometry, phylogeny and natural selection. The accelerated morphological evolution of the “guentheri” group can be explained by the fragmentation of the range and habitats. How to cite this article: Zorenko T., Kagainis U., Barashkova L. 2020. Does the geometric and linear morphometry of the brain reflect the divergence in the “guentheri” group (Arvicolinae, Sumeriomys)? // Russian J. Theriol. Vol.19. No.1. P.45–57. doi: 10.15298/rusjtheriol.19.1.04.