Shared environmental similarity between relatives influences heritability of reproductive timing in wild great tits.

Intraspecific variation is necessary for evolutionary change and population resilience, but the extent to which it contributes to either depends on the causes of this variation. Understanding the causes of individual variation in traits involved with reproductive timing is important in the face of environmental change, especially in systems where reproduction must coincide with seasonal resource availability. However, separating the genetic and environmental causes of variation is not straightforward, and there has been limited consideration of how small-scale environmental effects might lead to similarity between individuals that occupy similar environments, potentially biasing estimates of genetic heritability.

Seabirds show foraging site and route fidelity but demonstrate flexibility in response to local information.

Background: Fidelity to a given foraging location or route may be beneficial when environmental conditions are predictable but costly if conditions deteriorate or become unpredictable. Understanding the magnitude of fidelity displayed by different species and the processes that drive or erode it is therefore vital for understanding how fidelity may shape the demographic consequences of anthropogenic change. In particular, understanding the information that individuals may use to adjust their fidelity will facilitate improved predictions of how fidelity may change as environments change and the extent to which it will buffer individuals against such changes.

Phenotypic plasticity increases exposure to extreme climatic events that reduce individual fitness.

Climate models, and empirical observations, suggest that anthropogenic climate change is leading to changes in the occurrence and severity of extreme climatic events (ECEs). Effects of changes in mean climate on phenology, movement, and demography in animal and plant populations are well documented. In contrast, work exploring the impacts of ECEs on natural populations is less common, at least partially due to the challenges of obtaining sufficient data to study such rare events.

Social phenotype-dependent selection of social environment in wild great and blue tits: an experimental study.

There is growing evidence that individuals actively assess the match between their phenotype and their environment when making habitat choice decisions (so-called matching habitat choice). However, to our knowledge, no studies have considered how the social environment may interact with social phenotype in determining habitat choice, despite habitat choice being an inherently social process and growing evidence for individual variation in sociability. We conducted an experiment using wild great and blue tits to understand how birds integrate their social phenotype and social environment when choosing where and how to feed.

Having a better home range does not reduce the cost of reproduction in Soay sheep.

A cost of reproduction may not be observable in the presence of environmental or individual heterogeneity because they affect the resources available to individuals. Individual space use is critical in determining both the resources available to individuals and the exposure to factors that mediate the value of these resources (e.g.

Causes and consequences of an unusually male-biased adult sex ratio in an unmanaged feral horse population.

The adult sex ratio (ASR) is important within ecology due to its predicted effects on behaviour, demography and evolution, but research examining the causes and consequences of ASR bias have lagged behind the studies of sex ratios at earlier life stages. Although ungulate ASR is relatively well-studied, exceptions to the usual female-biased ASR challenge our understanding of the underlying drivers of biased ASR and provide an opportunity to better understand its consequences. Some feral ungulate populations, including multiple horse populations, exhibit unusually male-biased ASR.

Quantitative genetics of gastrointestinal strongyle burden and associated body condition in feral horses.

Variability in host resistance or tolerance to parasites is nearly ubiquitous, and is of key significance in understanding the evolutionary processes shaping host-parasite interactions. While ample research has been conducted on the genetics of parasite burden in livestock, relatively little has been done in free-living populations. Here, we investigate the sources of (co)variation in strongyle nematode faecal egg count (FEC) and body condition in Sable Island horses, a feral population in which parasite burden has previously been shown to negatively correlate with body condition.

Declining home range area predicts reduced late-life survival in two wild ungulate populations.

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 changes, and the consequences for fitness, remain unclear.

Sex differences in relationships between habitat use and reproductive performance in Soay sheep (Ovis aries).

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.

Asynchrony of senescence among phenotypic traits in a wild mammal population.

The degree to which changes in lifespan are coupled to changes in senescence in different physiological systems and phenotypic traits is a central question in biogerontology. It is underpinned by deeper biological questions about whether or not senescence is a synchronised process, or whether levels of synchrony depend on species or environmental context. Understanding how natural selection shapes patterns of synchrony in senescence across physiological systems and phenotypic traits demands the longitudinal study of many phenotypes under natural conditions.