Odor preferred males led to a higher offspring number in the common vole

Abstract

Abstract Very recently, an interesting phenomenon was described in the common vole; vole parents with similar locomotor ability produced significantly larger litters. Positive assortative mating is a tendency to prefer individuals with similar phenotypes. We tested whether this also applies to smell similarity. Odor preference was tested in a T-maze, where each female was presented with two male odors, i. e. shavings together with feces and urine from home boxes. After female preference was established, the female was either paired with a preferred male (chosen) or paired with a non-preferred male (opposite choice). For analysis of the relationship to odour preference, genotyping of MHC Class II DRB was done using amplicon sequencing. In the set of 45 individuals from two populations, we recovered 38 nucleotide haplotypes (alleles). Similarity of alleles in parent pairs according to the indexes of Sørensen-Dice (S-D) and Jaccard were calculated. Values of these indexes in parental pairs with preferred males were higher (more similar) than in not preferred (S-D: F(1, 20) = 8.489, p =0.009, Jaccard: F(1, 20) = 6.563, p = 0.019). The number of offspring in parental pairs with preferred males were higher than in not preferred (F(1, 20 ) = 4.915, p = 0.038). However, the correlation between the mentioned indexes and the number of offspring was very low. The relationship between the success of reproduction and alleles is not clear-cut, this may be influenced by the measure of similarity we used, or by something that we could not detect.