Judy Stamps

• PhD
• Professor Emeritus at University of California, Davis

Interest in individual differences in animal behavioural plasticities has surged in recent years, but research in this area has been hampered by semantic confusion as different investigators use the same terms (e.g. plasticity, flexibility, responsiveness) to refer to different phenomena. The first goal of this review is to suggest a framework for...

What makes individuals unique? The answer to this question lies in understanding why and how individuals respond to numerous internal and external factors that they experience over their lifetimes. This fundamental question lies at the heart of the study of human and animal behavior and is best addressed by integrating both proximate and ultimate p...

Experiences of parents and/or offspring are often assumed to affect the development of trait values in offspring because they provide information about the external environment. However, it is currently unclear how information from parental and offspring experiences might jointly affect the information-states that provide the foundation for the off...

Recent models of the evolution of sensitive periods in response to informative stimuli (i.e., cues) provide insights into reasons why empiricists within and across disciplines might observe variation in the patterns they observe when they study sensitive periods. We consider what an evolutionary perspective can tell us about the appropriate age to...

Interactions between genotypes and environments are central to evolutionary genetics, but such interactions are typically described, rather than predicted from theory. Recent Bayesian models of development generate specific predictions about genotypic differences in developmental plasticity (changes in the value of a given trait as a result of a gi...

Over the years, theoreticians and empiricists working in a wide range of disciplines, including physiology, ethology, psychology, and behavioral ecology, have suggested a variety of reasons why individual differences in behavior might change over time, such that different individuals become more similar (convergence) or less similar (divergence) to...

Appendices for Stamps&Bell 21

Experiences of parents and/or offspring are often assumed to affect the development of trait values in offspring because they provide information about the external environment, but it is currently unclear how information from different sources and times might combine to affect the information-states that provide the foundation for the patterns obs...

Empirical studies of phenotypic plasticity often use an experimental design in which the subjects in experimental treatments are exposed to cues, while the subjects in control treatments are maintained in the absence of those cues. However, researchers have virtually ignored the question of what, if any, information might be provided to subjects by...

Kamath and Losos (Kamath A, Losos J (2017) Behav Ecol Sociobiol 71:89) appropriately pointed out that researchers studying Anolis lizards have persisted for years in erroneously assuming that females only mate with the territorial male with whom they share space. However, Bush and Simberloff (Bush JM, Simberloff D (2018) Behav Ecol Sociobiol, in pr...

Christensen and Radford (2018) provide a masterful review of neighbor-stranger response differences (NSRD) in group-living species , one which is likely to spur further research on this topic. To that end, I here consider key criteria for determining whether territorial animals exhibit dear enemy (DE) or nasty neighbor (NN) effects, and list the st...

The rate of signal production by social ectotherms is often temperature dependent. This has been typically attributed to an underlying thermal constraint on physiology, but there are other reasons why signal rates might be correlated to temperature. We tested 3 hypotheses. The maximal performance hypothesis: temperature limits motor activity at col...

Recent models of sensitive periods and age-dependent changes in plasticity are based on the premise that animals use Bayesian-like processes to update information across ontogeny. Here we adopt this approach to consider how cues in the rearing environment, cues in the test environment and an individual's information state at birth or hatching (its...

Until recently, biology has lacked a framework for studying how information from genes, parental effects and different personal experiences is combined across the lifetime to affect phenotypic development. In the last few years researchers have begun building such a framework, using models that incorporate Bayesian updating to study the evolution o...

Behavioral plasticity is expected to facilitate the colonization of novel habitats by allowing populations to respond rapidly to abrupt environmental change. We studied contextual plasticity—a form of plasticity that allows an immediate phenotypic response to stimuli—in the territorial communication of Puerto Rican Anolis lizards and considered the...

Broad sense repeatability, which refers to the extent to which individual differences in trait scores are maintained over time, is of increasing interest to researchers studying behavioural or physiological traits. Broad sense repeatability is most often inferred from the statistic R (the intraclass correlation, or narrow sense repeatability). Howe...

© 2015 The Association for the Study of Animal Behaviour. Broad sense repeatability, which refers to the extent to which individual differences in trait scores are maintained over time, is of increasing interest to researchers studying behavioural or physiological traits. Broad sense repeatability is most often inferred from the statistic R (the in...

A persistent question in biology is how information from ancestors combines with personal experiences over the lifetime to affect the developmental trajectories of phenotypic traits.We address this question by modeling individual differences in behavioral developmental trajectories on the basis of two assumptions: (1) differences among individuals...

Changes in personality over ontogeny can occur even when every agent (individual or genotype) is exposed to the same set of cues, experiences or environmental conditions. A recent Bayesian model (Stamps and Krishnan, in press) shows how individual differences in the means and variances of prior distributions of estimates of variables such as danger...

Intra-genotypic variability (IGV) occurs when individuals with the same genotype, raised in the same environment and then tested under the same conditions, express different trait values. Game theoretical and bet-hedging models have suggested two ways that a single genotype might generate variable behaviour when behavioural variation is discrete ra...

To demonstrate adaptive convergent evolution, it must be shown that shared phenotypes have evolved independently in different lineages and that a credible selection pressure underlies adaptive evolution. There are a number of robust examples of adaptive convergence in morphology for which both these criteria have been met, but examples from animal...

Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies...

When an individual is repeatedly observed or tested in the same context, it does not always express the same behaviour. Intraindividual variability (IIV) refers to the short-term, unpredictable, reversible variation in behaviour that often occurs in this situation. Although individual differences in IIV have been well documented in humans, this top...

Developmental processes can have major impacts on the correlations in behaviour across contexts (contextual generality) and across time (temporal consistency) that are the hallmarks of animal personality. Personality can and does change: at any given age or life stage it is contingent upon a wide range of experiential factors that occurred earlier...

A major grand challenge in biology is to understand the interactions between an organism and its environment. Behavior resides in the central core of this association as it affects and is affected by development, physiology, ecological dynamics, environmental choice, and evolution. We present this central role of behavior in a diagram illustrating...

Adaptations that facilitate the reception of long-range signals under challenging conditions are expected to generate signal diversity when species communicate in different habitats. Although we have a general understanding of how individual communicating animals cope with conditions influencing signal detection, the extent to which plasticity and...

Consistent individual differences (CIDs) in behavior are a widespread phenomenon in animals, but the proximate reasons for them are unresolved. We discuss evidence for the hypothesis that CIDs in energy metabolism, as reflected by resting metabolic rate (RMR), promote CIDs in behavior patterns that either provide net energy (e.g. foraging activity)...

Recent studies of animal personality have focused on its proximate causation and its ecological and evolutionary significance, but have mostly ignored questions about its development, although an understanding of the latter is highly relevant to these other questions. One possible reason for this neglect is confusion about many of the concepts and...

Consistent individual differences in behaviour, termed personality, are common in animal populations and can constrain their responses to ecological and environmental variation, such as temperature. Here, we show for the first time that normal within-daytime fluctuations in temperature of less than 3 degrees C have large effects on personality for...

Researchers have suggested that animals should respond more strongly to conspecific than to heterospecific communication signals used in territorial or courtship contexts. We tested this prediction by reviewing studies that appeared in six prominent journals over the past 10 years. A meta-analysis based on these empirical studies revealed that over...

In many animals, exposure to cues in a natal habitat increases disperser preferences for those cues (natal habitat preference induction [NHPI]), but the proximate and ultimate bases for this phenomenon are obscure. We developed a Bayesian model to study how different types of experience in the natal habitat and survival to the age/stage of dispersa...

Habitat selection by natal dispersers is one of several contexts in which preexisting biases interact with experience to affect the attractiveness of cues from biologically significant items. Here we use a Bayesian approach to explore the conditions that favor this phenomenon. We demonstrate that the simplest possible type of natal experience--name...

Environmental noise that reduces the probability that animals will detect communicative signals poses a special challenge for long-range communication. The application of signal-detection theory to animal communication lead to the prediction that signals directed at distant receivers in noisy environments will begin with conspicuous “alerting” comp...

Animal personality traits such as boldness, activity and aggressiveness have been described for many animal species. However, why some individuals are consistently bolder or more active than others, for example, is currently obscure. Given that life-history tradeoffs are common and known to promote inter-individual differences in behavior, we sugge...

Natal dispersal occurs when young animals leave the area where they were born and reared and search the surrounding landscape for a new place to settle. Despite the importance of dispersal for both individuals and populations, search behavior by dispersers, including the decision-making process of choosing a place to settle, has not been investigat...

During natal dispersal, young animals leave their natal area and search for a new area to live. In species in which individuals inhabit different types of habitat, experience with a natal habitat may increase the probability that a disperser will select the same type of habitat post-dispersal (natal habitat preference induction or NHPI). Despite co...

Refractory periods at the onset of dispersal occur when individuals initially do not settle in response to cues from naturally occurring habitats. The current paper focuses on relationships between refractory periods and habitat selection behaviour when natal dispersers use sequential search tactics. We first show how individual differences in acce...

Consistent individual differences in boldness, reactivity, aggressiveness, and other 'personality traits' in animals are stable within individuals but vary across individuals, for reasons which are currently obscure. Here, I suggest that consistent individual differences in growth rates encourage consistent individual differences in behavior patter...

Recent insights from habitat selection theory may help conservation managers encourage released animals to settle in appropriate habitats. By all measures, success rates for captive–release and translocation programs are low, and have shown few signs of improvement in recent years. We consider situations in which free-living dispersers prefer new h...

Extensive research over the last few decades has revealed that many acoustically communicating animals compensate for the masking effect of background noise by changing the structure of their signals. Familiar examples include birds using acoustic properties that enhance the transmission of vocalizations in noisy habitats. Here, we show that the ef...

Despite considerable interest in the effects of natal experience on habitat selection, little attention has been paid to the adaptive significance of this behaviour. Here we suggest that experience in the natal habitat may provide dispersers with information that improves the decisions they make while searching for a new habitat. In animals with ti...

The silver spoon effect in the context of habitat selection occurs when dispersers in good condition are more likely to settle in high-quality habitats than dispersers in poor condition. Positive relationships between disperser condition and the quality of post-dispersal habitats are predicted by at least two non-exclusive ultimate hypotheses. The...

We studied the effects of natal experience on preference for a postdispersal habitat (natal habitat preference induction, NHPI) in groups of newly eclosed female Drosophila melanogaster, using multilevel statistical models to take into account dependencies of responses from individuals making choices within the same hour. Groups consisting of flies...

There are at least two reasons why animals searching for a new habitat might be attracted to cues produced by competitors, predators, or other factors that reduce their fitness after they arrive and settle in the new habitat. First, such cues may be associated with other factors that enhance fitness after arrival. A simple model illustrates the con...

We used five Drosophila melanogaster recurrent F1s to investigate genotypic differences in space use and movement patterns, focusing on the behaviour of teneral females and individually marked young adults that were allowed free access to large, structurally complex environments. Teneral females from the five F1s differed in their propensity to hid...

Animals are often attracted to one another when selecting habitats, but little is known about the rules governing conspecific attraction. We use Akaike Information Criterion to evaluate alternative models of the effects of conspecifics on individual choice in the context of habitat selection. One set of models was tested using data collected on vir...

The effects of search costs on habitat selection by dispersers are largely unknown. We explore how habitat selection behavior is affected by the risk of mortality en route and by deferred search costs (i.e., costs incurred during search that reduce fitness after arrival in the new habitat), using a model designed for long-distance natal dispersers...

Behavioural syndromes are correlations between behaviours in different contexts. For example, an individual's behaviour in response to a predator might be related to the same individual's behaviour towards conspecifics. We examined the developmental stability of single behaviours (activity in an unfamiliar environment, aggressive behaviour and bold...

Several important problems in ecology, evolution and conservation biology are affected by habitat selection in dispersing animals. Experience in the natal habitat has long been considered a potential source of variation in the habitat preferences displayed when dispersers select a post-dispersal habitat. However, the taxonomic breadth of this pheno...

Female-biased polymorphism is much more common than male-biased color pattern variability in species that fall prey to birds - it is a fairly common feature in butterflies and lizards especially, and it encompasses both mimetic and cryptic colour patterns. Hypotheses that could account for the preponderance of female bias are: differential predatio...

Interest in relationships between behaviour and development has been spurred by research on related topics, including phenotypic plasticity, parental effects, extragenetic inheritance, individual differences and trait syndromes. Here, I consider several emerging areas of research in the interface between behaviour and development, with a focus on b...

Summary The dual concern model suggests that pairs of animals can use four different behavioural strategies to resolve disputes that arise when making joint decisions. Based on their reproductive biology, we predicted that mated pairs of blue footed boobies would use one of these strategies, collaboration, when deciding on a location for their nest...

Complex bidirectional interactions between host social behaviour and infectious organisms (parasites) can be mediated by alterations in host glucocorticoid ‘stress’ hormones. As a result, an animal's social behaviour may affect its susceptibility to parasitism, and its infection status may influence its social behaviour. Our field study of behaviou...

Models of territorial defence tend to omit two characteristics of many territorial systems: repeated intrusions by the same individual and the learning processes of residents and intruders. Here we present state-dependent, dynamic models of feeding territories, designed to investigate temporal patterns of resident aggression towards intruders that...

Much of current habitat-selection theory assumes that individual fitness monotonically declines as a function of density, and that social interactions among settlers are entirely competitive. However, when animals settle at low densities, other fitness distributions (e.g., Allee effects) and positive interactions among settlers (e.g., conspecific c...

Trade-offs between growth and mortality can occur for a variety of reasons. These include foraging and predation risk, growth and mature function, growth and somatic development, growth and immune function, or growth and resistance to physiological stressors. We use a simple life-history model to show how individual trade-offs between growth and mo...

Behavioural research is shedding new light on the complex relationships between the proximate mechanisms involved in habitat selection and the selective pressures that may have contributed to the evolution of those mechanisms. Habitat selection by dispersers can be divided into three stages (search, settlement and residency); recent studies suggest...

It is widely assumed that aggressive behavior affects space acquisition in territorial species, but to date most workers have focused on competition for indivisible space, that is, space that cannot be divided or shared. We present a learning-based model that investigates the effects of aggressive interactions on space acquisition when unequal comp...

One of the factors that may influence an animal's use of space is visibility, which in territorial species can determine how readily an individual can monitor its territory for conspecific intruders. We hypothesized that territorial red-capped cardinals (Paroaria gularis) would prefer locations that provided them with good views of their territorie...

Despite widespread interest in territorial behavior, the processes by which animals establish territories are still poorly understood. We present a new learning-based model of territory establishment for species in which individuals set up territories within large patches of spatially heterogeneous habitat. The model is based on the simple assumpti...

A recent comparative study of anoles revealed a positive relationship between sexual size dimorphism as measured by asymptotic size (SSDas) and female density. The current study asks whether a comparable relationship exists between sexual size dimorphism as measured by average size (SSDavg) and female density across 25 samples of Anolis sagrei. A p...

The ability of juvenile black iguanas, Ctenosaura similis, to discriminate between the chemical cue of an unfamiliar and a familiar conspecific was tested. Lizards directed significantly more tongue extrusions toward the chemical cue of a size-matched conspecific with whom they had never interacted than the chemical cue of a size-matched conspecifi...

This paper examines similarities and differences between dominance and territoriality, focusing on the processes animals use to establish social relationships with one another. Dominance and territorial relationships are similar in many respects: in both situations, (a) social relationships affect the outcome of competition for important commoditie...

Comparative studies have revealed positive correlations between size at maturity and asymptotic size in several taxa with asymptotic growth after maturity. Using a simple growth model, we show that positive correlations between size at maturity and asymptotic size are predicted for different individuals in the same species if growth costs of reprod...

We released juvenile Anolis aeneus lizards into vacant patches of habitat in the field and observed as they established territories. Individuals settling in the presence of few competitors obtained more exclusive home ranges than did individuals settling at higher densities. When settling at high densities, juveniles that eventually attained high s...

Fights are often observed when prospective territory owners settle in patches of vacant habitat, but the function of these fights in space acquisition is obscure. This study tests two hypotheses about the effect of fights on subsequent space use patterns: first, that settlers win space by winning fights and, second, that fights encourage the establ...

In this study we test theoretical models of female mate choice tactics in natural populations of pine engravers, Ips pini (Say) (Coleoptera: Scolytidae), a species with a resource-based mating system and high search costs. We first develop distinguishing predictions for each of four models of mate choice: random, comparison tactics, and fixed and a...

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Many animal taxa exhibit a positive correlation between sexual size dimorphism and sex differences in age at maturity, such that members of the larger sex mature at older ages than members of the smaller sex. Previous workers have suggested that sexual bimaturation is a product of sex differences in growth trajectories, but to date no one has teste...

This chapter considers the role of females in the sexual and agonistic life of socially monogamous territorial species. Because of the obvious superficial similarities between such species and humans, this is a topic that has always attracted attention from evolutionary and behavioral biologists. However, despite longstanding interest in animal mon...

Sociobiology: Its Evolution and Intellectual Descendants - Volume 14 Issue 2 - Judy A. Stamps

Judging from studies of homing and territorial behavior, many animals value familiar home ranges or territories. This article discusses a new proximate explanation for this phenomenon: individuals may learn site-specific serial motor programs that enhance their ability to move rapidly, safely, and efficiently around obstacles and barriers in famili...

Juvenile Anolis aeneus lizards were released into patches of microhabitat in the field, and their social interactions and space use recorded throughout the settlement period. Two hypotheses about the role of social interactions in space acquisition were tested: (1) settlers win space by winning contests and (2) settlers win space by persistence. Re...

In animals with asymptotic growth after maturity, a variety of factors can lead to inter- and intraspecific variation in sexual size dimorphism (SSD). Growth-based models tailored for a particular taxon provide a useful framework for analyzing questions about the proximate bases, adaptive significance, and evolution of SSD. This paper shows how gro...

When animals mature at small sizes and then grow to larger asymptotic sizes, many different factors can affect adult male and female size distributions. This paper shows how growth-based models can be used to study the factors affecting sexual size dimorphism in species with asymptotic growth after maturity. Null growth-based models assume that the...

Null growth-based models were used to examine variation in sexual size dimorphism (SSD) in a population of the lizard Anolis limifrons in Panama. Females and males have comparable asymptotic body sizes, growth trajectories, size at maturity, and adult survival rates. The species is, thus, an unlikely candidate for a comparative analysis of SSD. Des...

Juvenile Anolis aeneus lizards were added to patches of microhabitat in the field and observed as they established territories. The outcome of the first encounter per dyad was an excellent predictor of the future dominance relationship between those individuals, and in the vast majority of dyads, the animal that won the first encounter won every su...

Examined factors related to the type (fight vs chase) and the outcome (win, loss, draw) of 1st encounters between dyads of juvenile lizards during the settlement period. The type of 1st encounters was influenced by relative body length and by the order in which Ss met novel opponents. Fights were more likely to occur if opponents were of similar si...

The visual displays of male anoles (Anolis sp.) are usually viewed as characters that facilitate species recognition. This presumption stems largely from the extensive variation in the head bobbing movements and dewlap colouration in males of this genus. However, few experimental data exist that illuminate the importance of these visual signals for...

In red-capped cardinals, Paroaria gularis, territorial birds form an 'early warning system' that serves to alert territory owners to the presence of an intruder in the area. Territorial cardinals were relatively likely to detect immediately intruders that were just evicted from a neighbour's territory, probably as a result of the conspicuous patter...

If animals mature at small sizes and then grow to larger asymptotic sizes, many factors can affect male and female size distributions. Standard growth equations can be used to study the processes affecting sexual size dimorphism in species with asymptotic growth after maturity. This paper first outlines the effects of sex differences in growth and...