Barbara Class

Ludwig-Maximilians-University of Munich | LMU · Faculty of Biology

How animals move and associate with conspecifics is rarely random, with a population’s spatial structure forming the foundation on which the social behaviours of individuals form. Studies examining the spatial–social interface typically measure averaged behavioural differences between individuals; however, this neglects the inherent variation prese...

Urbanization is occurring globally at an unprecedented rate and, despite the eco-evolutionary importance of individual variation, we still have limited insight on how phenotypic variation is modified by anthropogenic environmental change. Urbanization can increase individual differences in some contexts, but whether this is generalizable to behavio...

Social environments impose a number of constraints on individuals’ behaviour. These constraints have been hypothesized to generate behavioural variation among individuals, social responsiveness, and within-individual behavioural consistency (also termed ‘predictability’). In particular, the social niche hypothesis posits that higher levels of compe...

Social structure can have significant effects on selection, affecting both individual fitness traits and population-level processes. As such, research into its dynamics and evolution has spiked in the last decade, where theoretical and computational advances in social network analysis have increased our understanding of its ecological and inheritan...

In recent years, we have begun to appreciate that social behaviours might exhibit repeatable among-individual variation. Such behavioural traits may even covary and have critical evolutionary implications. Importantly, some social behaviours such as aggressiveness have been shown to provide fitness benefits, including higher reproductive success an...

Natural selection for territoriality is theorised to occur under conditions favouring intra-sexual phenotypic variation in physiology, morphology, and behaviour. In this context, certain suites of behavioural traits associated with territoriality are expected to consistently covary among individuals (sometimes referred to as ‘behavioural syndromes’...

Emerging infectious fungal diseases are responsible for the extinction of myriad species across a range of phyla. As recently shown by the COVID-19 pandemic, social transmission can be key to disease spread, and in this context, humans are not alone in trying to be alone. In group-living species, individuals have been shown to use social behaviour...

Oceanic archipelagos have long been treated as a petri dish for studies of evolutionary and ecological processes. Like archipelagos, cities exhibit similar patterns and processes, such as the rapid phenotypic divergence of a species between urban and non‐urban environments. However, on a local scale, cities can be highly heterogenous, where geograp...

Assortative mating occurs when paired individuals of the same population are more similar than expected by chance. This form of non‐random assortment has long been predicted to play a role in many evolutionary processes because assortatively mated individuals are assumed to be genetically similar. However, this assumption may always hold for labile...

Emerging infectious fungal diseases (EIFDs) represent a major conservation concern worldwide. Here, we provide early insights into the potential threat that Nannizziopsis barbatae (Nb), a novel EIFD, poses to Australian herpetological biodiversity. First known to the reptile pet trade as a primary pathogen causing untreatable severe dermatomycosis,...

Food-hoarding behaviour is widespread in the animal kingdom and enables predictable access to food resources in unpredictable environments. Within-species, consistent variation among individuals in food-hoarding behaviours may indicate the existence of individual strategies, as it likely captures intrinsic differences in how individuals cope with r...

Animal ecologists often collect hierarchically structured data and analyse these with linear mixed‐effects models. Specific complications arise when the effect sizes of covariates vary on multiple levels (e.g. within vs. among subjects). Mean centring of covariates within subjects offers a useful approach in such situations, but is not without prob...

Accurately estimating genetic variance components is important for studying evolution in the wild. Empirical work on domesticated and wild outbred populations suggests that dominance genetic variance represents a substantial part of genetic variance, and theoretical work predicts that ignoring dominance can inflate estimates of additive genetic var...

Repeatable behaviors (i.e., animal personality) are pervasive in the animal kingdom and various mechanisms have been proposed to explain their existence. Genetic and nongenetic mechanisms, which can be equally important, predict correlations between behavior and body mass on different levels (e.g., genetic and environmental) of variation. We invest...

Multivariate mixed models (MMM) are generalized linear models with both fixed and random effect having multiple response variables. MMM allow partitioning of total (phenotypic) (co)variances for multiple traits into (co)variances on hierarchically lower levels. We outline why ecologists and evolutionary biologists should be interested in such parti...

Animal personality traits are often heritable and plastic at the same time. Indeed, behaviors that reflect an individual's personality can respond to environmental factors or change with age. To date, little is known regarding personality changes during a wild animals' lifetime and even less about stability in heritability of behavior across ages....

Indirect sexual selection arises when reproductive individuals choose their mates based on heritable ornaments that are genetically correlated to fitness. Evidence for genetic associations between ornamental coloration and fitness remain scarce. In this study we investigate the quantitative genetic relationship between different aspects of tail str...

Among all environmental factors, food supply is thought to be the most important cause of variation in phenotype, for it is the fuel for development. During 10 years, we collected data on caterpillar biomass in birches (Betula sp.) and on 752 broods of blue tits (Cyanistes caeruleus) in a boreal forest of Southwest Finland. The aim was to investiga...

Assortative mating is pervasive in wild populations and commonly described as a positive correlation between the phenotypes of males and females across mated pairs. This correlation is often assumed to reflect non-random mate choice based on phenotypic similarity. However, phenotypic resemblance between mates can also arise when their traits respon...

Behavioral ecologists consider behaviors that show significant between-individual variation as aspects of personality. When multiple aspects of personality covary, these are viewed as a behavioral syndrome. Meta-analyses have demonstrated that behaviors typically are repeatable and that behavioral syndromes are common across a wide variety of taxa....

1. Assortative mating in wild populations is commonly reported as the correlation between males’ and females’ phenotypes across mated pairs. Theories of partner selection and quantitative genetics assume that phenotypic resemblance of partners captures associations in “intrinsically determined” trait values. However, when considering traits with a...

The presence of variation in behavior on the between-individual level is considered the hallmark of personality. In contrast, behavioral syndromes are commonly recognized when documented on the phenotypic level, which is a mix of between-individual and residual (within-individual) correlations. Phenotypic and between-individual correlations need no...

Despite a growing body of literature reporting developmental changes in personality, few studies have adopted a lifetime perspective to study age-related changes in personality traits. Since most personality traits are heritable and linked with fitness, ontogenetic changes can have evolutionary implications. In this paper, we explore age-related ch...

Overview of literature estimates of the correlation of behavioral traits across age classes

R script for producing the simulations in this paper

Overview of the literature considering changes in the correlation between two or more behavioral traits across ages

Glossary of terms used in this paper

Schematic illustration of how changes in the age-specific expression of behavior by an individual are modelled as deviations from the age-specific mean

Behaviors are highly plastic and one aspect of this plasticity is behavioral changes over age. The presence of age-related plasticity in behavior opens up the possibility of between-individual variation in age-related plasticity (Individual-Age interaction, IxA) and genotype-age interaction (GxA). We outline the available approaches for quantifying...

In animal populations, as in humans, behavioural differences between individuals that are consistent over time and across contexts are considered to reflect personality, and suites of correlated behaviours expressed by individuals are known as behavioural syndromes. Lifelong stability of behavioural syndromes is often assumed, either implicitly or...

Behavioral differences between individuals that are consistent over time characterize animal personality. The existence of such consistency contrasts to the expectation based on classical behavioral theory that facultative behavior maximizes individual fitness. Here, we study two personality traits (aggression and breath rate during handling) in a...

When crossing the road, pedestrians have to make a trade-off between saving time and avoiding any risk of injuries. Here, we studied how culture influences an individual's perception of risks when crossing a street, using survival analysis. This study is the first to use this analysis to assess cognitive mechanisms and optimality of decisions under...