Stabilizing selection on microsatellite allele length at arginine vasopressin 1a receptor and oxytocin receptor loci.

Esa Koskela,Eva R. Kallio,Phillip C. Watts,Mikael Mokkonen,Eija Lonn,Tapio Mappes

doi:10.1098/rspb.2017.1896

Abstract

The loci arginine vasopressin receptor 1a (avpr1a) and oxytocin receptor (oxtr) have evolutionarily conserved roles in vertebrate social and sexual behaviour. Allelic variation at a microsatellite locus in the 5′ regulatory region of these genes is associated with fitness in the bank vole Myodes glareolus. Given the low frequency of long and short alleles at these microsatellite loci in wild bank voles, we used breeding trials to determine whether selection acts against long and short alleles. Female bank voles with intermediate length avpr1a alleles had the highest probability of breeding, while male voles whose avpr1a alleles were very different in length had reduced probability of breeding. Moreover, there was a significant interaction between male and female oxtr genotypes, where potential breeding pairs with dissimilar length alleles had reduced probability of breeding. These data show how genetic variation at microsatellite loci associated with avpr1a and oxtr is associated with fitness, and highlight complex patterns of selection at these loci. More widely, these data show how stabilizing selection might act on allele length frequency distributions at gene-associated microsatellite loci.

Highlights

Genes within the vasopressin–oxytocin pathway represent an interesting model of mate choice as they regulate social and reproductive behaviours in diverse taxa [1,2,3]
M. glareolus, allele length is associated with fitness at the microsatellite locus located in the 50 regulatory region of avpr1a; males with longer avpr1a alleles sired more offspring than did & 2017 The Authors
We examined the probability that animals produced offspring (1 1⁄4 yes, 0 1⁄4 no) after an opportunity to mate in relation to microsatellite allele length at avpr1a and oxtr, as microsatellite allele length had little effect on the litter size of the breeding voles

Summary

Introduction

Genes within the vasopressin–oxytocin pathway represent an interesting model of mate choice as they regulate social and reproductive behaviours in diverse taxa [1,2,3]. Allelic variation at a microsatellite locus located upstream of the oxtr transcription start site in the bank vole is associated with fitness, for example, with shorter oxtr alleles increasing male reproductive success [19] One corollary of these studies is the potential for selection on microsatellite allele length. To test the hypothesis that selection acts against long and short alleles, we quantified breeding success in bank voles with different microsatellite genotypes at arginine vasopressin receptor 1a (avpr1a) and oxytocin receptor (oxtr) loci. We concentrate on these loci as they (i) show clear fitness effects in microtine voles and (ii) have evolutionarily conserved roles in vertebrate social and sexual behaviour [1,2,3]. Model selection was based on AICc, using the dredge function (in MuMIn) to identify the best model

Results

Discussion

Findings

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