Vitamin D status is heritable and under environment-dependent selection in the wild.

Alexandra M Sparks,Jacqueline Berry,Richard J Mellanby,Josephine M Pemberton,Ian Handel,Susan E Johnston,Jill G Pilkington,Daniel H Nussey

doi:10.1111/mec.16318

Abstract

Vitamin D has a well‐established role in skeletal health and is increasingly linked to chronic disease and mortality in humans and companion animals. Despite the clear significance of vitamin D for health and obvious implications for fitness under natural conditions, no longitudinal study has tested whether the circulating concentration of vitamin D is under natural selection in the wild. Here, we show that concentrations of dietary‐derived vitamin D2 and endogenously produced vitamin D3 metabolites are heritable and largely polygenic in a wild population of Soay sheep (Ovis aries). Vitamin D2 status was positively associated with female adult survival, and vitamin D3 status predicted female fecundity in particular, good environment years when sheep density and competition for resources was low. Our study provides evidence that vitamin D status has the potential to respond to selection, and also provides new insights into how vitamin D metabolism is associated with fitness in the wild.

Highlights

Vitamin D is a critical component in the development and maintenance of skeletal health (Elder & Bishop, 2014)
This study investigated the genetic architecture underlying vitamin D status in a wild mammal population and associations with fitness under natural conditions
We demonstrate that vitamin D status is repeatable within the lifetime of individuals and is moderately heritable

Summary

| INTRODUCTION

Vitamin D is a critical component in the development and maintenance of skeletal health (Elder & Bishop, 2014). Current research suggests that vitamin D may have wider biomedical effects, with studies linking vitamin D insufficiency to increased risk of mortality in humans and companion animals (Schöttker et al, 2014; Titmarsh, Gow, et al, 2015; Titmarsh, Kilpatrick, et al, 2015), as well as reproductive failure, low birth weight, infertility and reduced litter sizes in humans, rats and mice (Halloran & Deluca, 1980; Luk et al, 2012; Tous et al, 2019; Yoshizawa et al, 1997) This link suggests that vitamin D status may be associated with fitness in natural populations, yet there have been no investigations into the causes and consequences of its variation in wild populations. |2 environmental variation, the extent to which it is heritable and the underlying genetic architecture, and its association with key components of fitness, such as survival and fecundity By investigating these factors, we can begin to understand the evolutionary potential of vitamin D status and determine if it is under selection in natural conditions. We use samples collected longitudinally over a 6-year period, alongside detailed information on the genetics and life histories of the individuals sampled, to: (i) estimate the heritability of vitamin D status in the wild; (ii) use a GWAS approach to determine the genetic architecture of vitamin D status; and (iii) examine how vitamin D status predicts survival and reproductive performance

| METHODS

| RESULTS

Findings

| DISCUSSION