PT  - JOURNAL ARTICLE
AU  - Emily B. Josephs
AU  - Young Wha Lee
AU  - John R. Stinchcombe
AU  - Stephen I. Wright
TI  - Association mapping reveals the role of mutation-selection balance in the maintenance of genomic variation for gene expression
AID  - 10.1101/015743
DP  - 2015 Jan 01
TA  - bioRxiv
PG  - 015743
4099  - http://biorxiv.org/content/early/2015/02/26/015743.short
4100  - http://biorxiv.org/content/early/2015/02/26/015743.full
AB  - The evolutionary forces that maintain genetic variation for quantitative traits within populations remain unknown. One hypothesis suggests that variation is maintained by a balance between new mutations and their removal by selection and drift. Theory predicts that this mutation-selection balance will result in an excess of low-frequency variants and a negative correlation between minor allele frequency and selection coefficients. Here, we test these predictions using the genetic loci associated with total expression variation (‘eQTLs’) and allele-specific expression variation (‘aseQTLs’) mapped within a single population of the plant Capsella grandiflora. In addition to finding eQTLs and aseQTLs for a large fraction of genes, we show that alleles at these loci are rarer than expected and exhibit a negative correlation between effect size and frequency. Overall, our results show that mutation-selection balance is the dominant contributor to genomic variation for expression within a single, outcrossing population.