Intra-species structuring in the common shrew Sorex araneus (Lipotyphla: Soricidae) in European Russia: morphometric variability could give evidence of limitation of interpopulation migration

Abstract

The shape of the skull, mandible, and first lower molar (m1) in 10 geographical samples from four chromosomal races of two karyotypic groups were studied using geometric morphometrics. Discrimi- nant analysis with cross-validation was used to test the accuracy of classifications of specimens using skull shape. The percentage of correct classifications attributed to race varied from 61.8% to 89.5% and ranged from 51.6% to 82.3% for geographical samples. The structuring between races, as measured with Q st (this metric is analogous to F st , and the latter is used as a measure of genetic disparity between samples), was less than population-level structuring both within and between races. Variance between karyotypic groups in skull size, mandible, and molar shape was greater than between races. In skull shape, the variance was smaller as compared to the inter-racial level without larger mountain samples and greater when the entire set of samples was estimated. Interpopulation differences in all census characteristics were the most prominent. The magnitude of Q st in interpopulation estimations was similar both among populations of the same race and among populations of different races. Lack of correlation of Q st level with geographical distance between samples was found both in size and shape of the skull, mandible, and first lower molar. The significant difference between populations within a race was regarded as evidence of limitation of interpopulation migration. Each pair of geographic samples has a unique set of differentiating features. The stochastic variability of traits between the local samples, irrespective of race, is interpreted as evidence of genetic drift within partly isolated local populations. Diminishing differences between races could be a consequence of reabsorbing those stochastic morphological differences back into the metapopulations. The greater level of phenotypic differentiation between karyotypic groups compared to races is interpreted as a greater amount of time elapsed since the time of common ancestry.