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 d...

Predicting how species will be affected by future climatic change requires the underlying environmental drivers to be identified. As vital rates vary over the lifecycle, structured population models derived from statistical environment–demography relationships are often used to inform such predictions. Environmental drivers are typically identified independently for different vital rates and demographic classes. However, these...

Demographic senescence is increasingly recognised as an important force shaping the dynamics of wild vertebrate populations. However, our understanding of the processes that underpin these declines in survival and fertility in old age remains limited. Evidence for age‐related changes in foraging behaviour and habitat use is emerging from wild vertebrate studies, but the extent to which these are driven by within‐individual cha...

Mounting evidence suggests that average telomere length reflects previous stress and predicts subsequent survival across vertebrate species. In humans, leucocyte telomere length ( LTL ) is consistently shorter during adulthood in males than in females, although the causes of this sex difference and its generality to other mammals remain unknown. Here, we measured LTL in a cross‐sectional sample of free‐living Soay sheep and fo...

The role of habitat use in generating individual variation in fitness has rarely been examined empirically in natural populations of long‐lived mammals, particularly for both sexes simultaneously. This is the case despite the increase in studies attempting to understand evolutionary change in such populations. Using data from the St. Kilda Soay sheep population, we quantified the association between lifetime reproductive perfo...

Identifying the genes underlying phenotypic variation in natural populations can provide novel insight into the evolutionary process. The candidate gene approach has been applied to studies of a number of traits in various species, in an attempt to elucidate their genetic basis. Here, we test the application of the candidate gene approach to identify the loci involved in variation in gastrointestinal parasite burden, a complex...

Understanding the maintenance of genetic variation in natural populations is a core aim of evolutionary genetics. Insight can be gained by quantifying selection at the level of the genotype, as opposed to the phenotype. Here, we show that in a natural population of Soay sheep which is polymorphic for coat pattern, recessive genetic variants at the causal gene, agouti signalling protein ( ASIP ) are associated with reduced life...

Digital gene expression (DGE) analysis offers a route to gene discovery which by‐passes the need to develop bespoke arrays for nonmodel species, and is therefore a potentially valuable tool for molecular ecologists. Scottish blackface sheep, which vary in resistance to the common abomasal parasitic nematode Teladorsagia circumcincta, were trickle‐infected with L3 larvae over 3 months to mimic the natural progression of infecti...

We investigated temporal changes in hybridization and introgression between native red deer ( Cervus elaphus ) and invasive Japanese sika ( Cervus nippon ) on the Kintyre Peninsula, Scotland, over 15 years, through analysis of 1513 samples of deer at 20 microsatellite loci and a mtDNA marker. We found no evidence that either the proportion of recent hybrids, or the levels of introgression had changed over the study period. Nev...

Landscape features have been shown to strongly influence dispersal and, consequently, the genetic population structure of organisms. Studies quantifying the effect of landscape features on gene flow of large mammals with high dispersal capabilities are rare and have mainly been focused at large geographical scales. In this study, we assessed the influence of several natural and human‐made landscape features on red deer gene fl...

The Florida Everglades have been invaded by an exotic weed fern, Lygodium microphyllum . Across its native distribution in the Old World tropics from Africa to Australasia it was found to have multiple location‐specific haplotypes. Within this distribution, the climbing fern is attacked by a phytophagous mite, Floracarus perrepae, also with multiple haplotypes. The genetic relationship between mite and fern haplotypes was matc...

We investigated whether birth weight and neonatal survival, a period within which 24% of all mortalities occur, were correlated with levels of inbreeding in St Kilda Soay sheep, using pedigree inbreeding coefficients and four marker‐based estimators of inbreeding. None of the inbreeding estimators, either of the offspring, or of their mothers, explained significant variation in a lamb's birth weight or probability of surviving...

The fine‐scale genetic structure of wild animal populations has rarely been analysed, yet is potentially important as a confounding factor in quantitative genetic and allelic association studies, as well as having implications for population dynamics, inbreeding and kin selection. In this study, we examined the extent to which the three spatial subunits, or hefts, of the Village Bay population of Soay sheep (O vis aries ) on S...

A migratory divide usually signals the presence of a geographical region over which other traits, such as morphology and genotypes, also undergo rapid change. A migratory divide has been hypothesized in central southern Africa for the abundant migratory weaver, the red‐billed quelea Quelea quelea . The positioning of the divide in the region is based on the patterns of rainfall in the region that stimulate the annual migration...

In order to detect sex‐biased dispersal in the red‐billed quelea Quelea quelea in southern Africa, we used the assignment index technique to determine the probability that individuals originated from the population in which they were sampled. This is the first time that this multilocus genetic test has been used in a bird species and is informative despite evidence that the population under study exhibits little genetic struct...