Carsten Schradin

Carsten Schradin
Hubert Curien Pluridisciplinary Institute | IPHC · Department of Ecology, Physiology and Ethology

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About

197
Publications
59,160
Reads
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Introduction
https://www.youtube.com/watch?v=vZmAXySr-EM I study behavioral and physiological flexibility enabling animals to respond to droughts, one consequence of climate change.
Additional affiliations
October 2014 - present
Hubert Curien Pluridisciplinary Institute
Position
  • DR2 (Directeur de Recherche de second Classe)
May 2001 - September 2005
University of the Witwatersrand
Position
  • PostDoc Position
December 1997 - April 2001
University of Zurich
Position
  • PhD Student

Publications

Publications (197)
Book
Full-text available
Newsletter about studying solitary living
Article
Full-text available
In short-lived animals, individuals born earlier in the breeding season frequently reproduce within the season of birth. Consequently, it has been proposed that those born early benefit from a more proactive behavioral type to compete for reproductive opportunities whereas later-borns adopt a more reactive personality to conserve energy to survive...
Article
Full-text available
Many mammal species are thought to adopt solitary living owing to mothers becoming intolerant of adult offspring and the occurrence of social intolerance between adults. However, field studies on how solitary mammals interact are rare. Here we show that solitary living can occur without social intolerance. Over 3 years, we recorded interactions bet...
Article
Full-text available
Mouse‐like rodents often take cover in natural shelters or burrow underground where they build simple nests. A few species build extensive shelters above ground, called lodges, mounds or houses. Here, we present the first phylogenetically controlled comparative study on the ecological factors of habitat heterogeneity, environmental aridity and fire...
Preprint
Full-text available
In short-lived animals, individuals born earlier in the breeding season frequently reproduce within the season of birth. Consequently, it has been proposed that those born early benefit from a more proactive behavioral type to compete for reproductive resources whereas later-borns adopt a more reactive personality to conserve energy to survive thro...
Article
Full-text available
Keywords: intraspecific variation in social organization kinship kin selection social organization social structure social system solitary spatial structure Kin selection is important for understanding the evolution of social behaviour in group-living species. Yet, the role of kinship in solitary species has received little attention. We studied ho...
Preprint
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Kinship is important for understanding the evolution of social behaviour in group living species. However, even solitary living individuals differentiate between kin and non-kin neighbours, which could lead to some form of cooperation, defined as both partners benefitting from each other. A simple form of cooperation is mutualism, where both partne...
Preprint
Full-text available
Many mammal species are thought to adopt solitary living due to mothers becoming intolerant of their adult offspring as well as social intolerance between adults. However, field studies on how solitary mammals interact are rare. Here we show that solitary living can occur without social intolerance. Over three years, we recorded interactions betwee...
Preprint
Mice exchange information using chemical, visual and acoustic signals. Long ignored, mouse ultrasonic communication is now considered to be an important aspect of their social life, transferring information such as individual identity or stress levels. However, whether and how mice modulate their acoustic communications is largely unknown. Here we...
Preprint
Full-text available
Research on cooperative breeding (a system with the core characteristic of individuals providing care for the offspring of others) is important for understanding sociality and cooperation. However, large-scale comparative analyses on the drivers and consequences of cooperation frequently use considerably inaccurate datasets (e.g. due to inconsisten...
Article
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Background: Evolutionary medicine builds on evolutionary biology and explains why natural selection has left us vulnerable to disease. Unfortunately, several misunderstandings exist in the medical literature about the levels and mechanisms of evolution. Reasons for these problems start from the lack of teaching evolutionary biology in medical schoo...
Article
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While for decades behavioural ecologists have studied the costs and benefits of group living, solitary living has received little attention. Instead, it was assumed to be the default stage from which sociality evolved. Mammals underwent around 200 million years of social evolution, with a few species evolving communal or cooperative breeding in har...
Article
Full-text available
Explaining the evolution of primate social organization has been fundamental to understand human sociality and social evolution more broadly. It has often been suggested that the ancestor of all primates was solitary and that other forms of social organization evolved later, with transitions being driven by various life history traits and ecologica...
Article
Full-text available
The ability to alter the mass of energetically consumptive organs in response to seasonal variation in nutritional access has been demonstrated in several species from temperate climates, but less so from other climate zones. We predicted that adult striped mice (Rhabdomys pumilio) from the Succulent Karoo semi-desert in South Africa have lower org...
Article
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Home ranges of free-living mammals have typically been studied via radio-tracking to understand how individuals use their environment. Recently, GPS collars have become popular in large mammals. However, GPS collars are rarely used in small mammals, as they are too heavy, especially when needing coating to protect against gnawing. Here we test the...
Article
Full-text available
Cognition is shaped by evolution and is predicted to increase fitness. However, the link between cognition and fitness in free-living animals is unresolved. We studied the correlates of cognition and survival in a free-living rodent inhabiting an arid environment. We tested 143 striped mice (Rhabdomys pumilio) using a battery of cognitive tests, in...
Article
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In a recent publication, (Besedovsky and Del Rey, 2022) asked why the immune system, which evolved to protect the individual against disease, sometimes causes death. They argue that lethal cytokine overreaction evolved for the benefit of the species by negative selection of individuals that would otherwise spread the infectious disease. Since the 1...
Article
We must differentiate between stressful and harsh environments to understand animals’ resilience to global change. Harshness is not stress. Stressful environments activate the physiological stress response to increase energy avail- ability, while harsh environments inhibit the physiological stress response to save energy.
Article
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ABSTRACT – Invasive pond sliders (Trachemys scripta) have been released in thousands of freshwaters within Europe and reproduce in the southern states and even in warm areas of Germany. All member states of the European Union must have an action plan how to fight this invasive species. The German action plan focusses on informing the public, but to...
Article
Full-text available
It is generally believed that marsupials are more primitive than placentals mammals and mainly solitary living, representing the ancestral form of social organization of all mammals. However, field studies have observed pair and group-living in marsupial species, but no comparative study about their social evolution was ever done. Here, we describe...
Preprint
Explaining the evolution of primate social organization has been fundamental to understand human sociality and social evolution more broadly. It has often been suggested that the ancestor of all primates was solitary and that other forms of social organization evolved later. However, previous research included the assumption that many understudied...
Preprint
Invasive pond sliders ( Trachemys scripta ) have been released in thousands of freshwaters within Europe and reproduce in the southern states and even in warm areas of Germany. All member states of the European Union must have an action plan how to fight this invasive species. The German action plan focusses on informing the public, but to date no...
Article
Full-text available
Innovative problem-solving ability is a predictor of whether animals can successfully cope with environmental changes. These environmental changes can test the limits of animals, for example when energy availability decreases seasonally and, hence, problem-solving performance decreases because less energy is available for cognitive processes. Here,...
Article
Elephant‐shrews (Macroscelidea) have long been considered the only mammalian order to be completely monogamous, based on observations of their pair‐living social organization. We reviewed primary studies on the four components of social systems (social organization, mating system, social structure, and care system) in elephant‐shrews to evaluate wh...
Article
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Social systems vary within and between species, ranging along a continuum between solitary-living to complex societies. Social systems are emergent properties of interactions between individuals, and these interactions are often modulated by hormones. We investigated the behavioral and hormonal consequences of experimentally imposed social grouping...
Presentation
Full-text available
Students never learn how to write a proper application letter. Here I will report from my point of view why I reject most applications after having spent 1-3min reading it, and what needs to be stated in an application letter. I will bring examples from recent applications I received and provide a template for how to write an application letter.
Article
Full-text available
Comparative studies on social evolution are ideally based on large datasets to ensure high statistical power, but their scientific validity also relies on the quality of the data. However, even though social organisation, that is the composition of social units, is measured in many field studies testing specific hypotheses, these data are often not...
Article
In several mammal species, bachelor groups occur as a regular life history stage between dispersal and becoming the breeding male of a multifemale group. How such groups come into existence and how males that choose this strategy differ in life history traits from other males is rarely investigated. Males of the socially flexible African striped mo...
Article
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Life history traits are adaptations to specific environmental conditions but are also phylogenetically constrained. We studied life history traits of free-living bush Karoo rats (Otomys unisulcatus) that are endemic to the semi-arid regions of South Africa. They show behavioural, rather than physiological, adaptations to arid environments, which mi...
Article
In response to the COVID-19 crisis, numerous academic conferences and seminars were moved online. Some remote (online) seminars have the aim to be maintained permanently after the pandemic, offering weekly opportunities for scientists, postdocs, and students to learn about research and to improve global networking. Remote seminars are a good option...
Article
Full-text available
In changing environments, animals face unexpected problems to solve. Not all individuals in a population are equally able to solve new problems. It still remains unclear what factors (e.g. age and body condition) influence the propensity of problem solving. We investigated variation in problem-solving performance among males following alternative r...
Article
Most scientists agree that we have to restrict climate change, but there is much frustration that we are failing. The Corona Crisis exemplifies how human behavior is constrained by its evolution, cognition, and resource availability, explaining why we do not act to avoid climate change for the benefit of future generations.
Article
Studying how different environmental parameters, such as resource availability and ambient temperature, affect growth rates aids to understand the evolution of different growth strategies. Low levels of food availability restrict growth, and high ambient temperature can constrain growth via trade-offs between body temperature maintenance and heat p...
Article
Full-text available
The European Union categorises pond sliders (Trachemys scripta) as invasive species for which all member countries have to develop an action plan. To date it has been assumed that the climate in Germany is too cold for T. scripta to survive or reproduce. Data collected annually from 2016 to 2020 show that the population of exotic pond turtles in an...
Article
Full-text available
Facultatively social species, in which individuals can switch between group‐ and solitary‐living tactics, offer an opportunity to shed light on proximate mechanisms underlying alternative life histories. Promising hormonal mediators of social tactic include glucocorticoids, which control energy allocation and are negatively related to body conditio...
Article
Full-text available
Telomere shortening has been used as an indicator of aging and is believed to accelerate under harsh environmental conditions. This can be attributed to the fact that telomere shortening has often been regarded as non-reversible and negatively impacting fitness. However, studies of laboratory mice indicate that they may be able to repair telomere l...
Article
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Personality traits (e.g. activity, exploration, boldness) are frequently correlated with each other and with various other traits of biological importance. According to the performance, allocation, and independent models of energy management, the relationship between personality traits and resting metabolic rate (RMR) is predicted to be either posi...
Article
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Social flexibility enables individuals to switch between group and solitary living and is suggested to be an adaptation to varying environments. Several previous studies on different species compared two populations and hypothesized that observed differences in the social organization were due to differences in population density but lacked the nec...
Presentation
Full-text available
SCHRADIN Mammalian Social Evolution teaching slides FINE seminar series. Five slides for teaching animal behavior: Why do animals live in groups, why do animals live solitaryily? These slides explain a case study on African striped mice and how ecological constraints and reproductive competition shape their social system.
Presentation
Full-text available
This is a set of 5 slides that can be used when teaching Behavioural Ecology or similar at University. These slides explain the concept of "Intra-specific variation in social organization" and the four mechanisms that can cause it, as well how common it is in mammals.
Preprint
Full-text available
The European Union categorised pond sliders (Trachemys scripta) as an invasive species for which all member countries have to develop an action plan. While T. scripta has been released illegally in thousands of freshwaters in Europe, monitoring programs in Germany are missing. Based on short term surveys, anecdotal data, and assumptions, the action...
Article
Full-text available
Previous studies to understand the evolution of interspecific variation in mammalian social organization (SO; composition of social units) produced inconsistent results, possibly by ignoring intraspecific variation. Here we present systematic data on SO in artiodactyl populations, coding SO as solitary, pair-living, group-living, sex-specific or va...
Chapter
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“Nothing in Biology makes sense, except in the light of evolution.” This famous citation of Theodosius Dobzhansky also underlies the integrative field of evolutionary medicine, which faces the challenge to combine (patho-)physiological mechanisms with evolutionary function. Here we introduce a concept from the study of animal behavior, which are th...
Article
Full-text available
In some species, cognition can change flexibly in response to environmental changes. These changes can be adaptive or can result from physiological constraints, such as when energy availability decreases seasonally. Here, we investigated: (1) how cognitive performance changes between seasons that differ significantly in food availability; (2) how t...
Article
Full-text available
Individuals that are capable of accumulating appropriate fat stores are assumed to have selective advantages when food becomes scarce. Similar to species from temperate zones, some species inhabiting arid areas accumulate fat stores prior to periods of food limitation. Yet, we have little knowledge concerning seasonal variation in body composition...
Chapter
Full-text available
Huddling is defined as mutualistic social thermoregulation where two or more animals are in body contact, increasing body temperature (ectotherms), or decreasing costs of thermoregulation (endotherms). Typically, huddling occurs in resting (including sleeping) individuals, but in penguins it can also occur in moving individuals (moving huddles of b...
Article
Full-text available
The resilience of an individual to environmental change depends on its ability to respond adaptively. Phenotypic flexibility, i.e., reversible phenotypic plasticity, is such an adaptive response, which has been predicted to evolve in unpredictable environments. We present data on the environmental predictability for 17 generations of socially flexi...
Article
Full-text available
Basking in the sun is an important energy‐saving tactic in ectotherm animals. It has also been recognized to be important in several mammal species, especially in arid environments. In particular, small mammals that have a greater surface‐to‐volume ratio can use basking to reduce metabolic energy expenditure by using external heat to maintain a hig...
Article
According to the cort-fitness hypothesis, glucocorticoid levels correlate negatively with fitness. However, field studies found mixed support for this hypothesis, potentially because the association between glucocorticoids and fitness might depend on prevailing environmental conditions. Based on the long-term monitoring of a natural rodent populati...
Preprint
Full-text available
Understanding inter-specific variation in social systems is a major goal of behavioural ecology. Previous comparative studies of mammalian social organisation produced inconsistent results, possibly because they ignored intra-specific variation in social organisation (IVSO). The Artiodactyla have been the focus of many comparative studies as they o...
Article
Full-text available
Pair bonding (i.e. individuals showing a preference for a specific opposite-sex individual) has been demonstrated in several socially monogamous species. However, social bonds also occur in nonmonogamous species, but have received less attention. Currently, we do not know whether social bonds in monogamous pairs differ from social bonds in polygyno...
Chapter
Full-text available
Alternative reproductive tactics (ARTs) refer to the consistent use of different reproductive behaviors between conspecifics of the same sex in one population at the same time. Hereby the difference between individuals is discontinuous, such that one can put individuals into two or more categories. A tactic refers to the behavioral phenotype, which...
Chapter
Full-text available
Definition The reduced attack-to-kill ratio of a predator resulting from its inability to single out and catch an individual surrounded by other individuals. In other words, it is more difficult for predators to capture prey that is surrounded by other conspecifics than to capture an isolated individual. What Is the "Confusion" in the Confusion Eff...
Article
In many species, males follow alternative reproductive tactics (ARTs), where one tactic (called bourgeois) has much higher reproductive success than alternative tactics followed by males with lower competitive ability. The extent to which ARTs differ in energetic costs is unknown, but it is important to understand the fitness payoffs of ARTs. We st...
Article
Family groups with helpers occur in several species of fish, birds and mammals. In such cooperatively breeding species all group members help with raising the offspring, i.e. parents and offspring from previous litters. While the ecological reasons and ultimate consequences of allo-parental care have been studied in detail, we know little about its...
Article
Full-text available
Animals that spend more energy than they obtain risk entering allostatic overload, reducing survival and fitness. They are predicted to adjust their daily energy expenditure (DEE) during periods of food scarcity. Adjustments of DEE to changes in food availability have been well-studied in species in temperate zones during winter, but less so in spec...
Article
Population dynamics are the result of an interplay between extrinsic and intrinsic environmental drivers. Predicting the effects of environmental change on wildlife populations therefore requires a thorough understanding of the mechanisms through which different environmental drivers interact to generate changes in population size and structure. In...
Article
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There was an error published in J. Exp. Biol. (2017) 220, 837-843 (doi: 10.1242/jeb.151449). A mistake was made by the authors in the calculation of RMR values. The corrected Results section, tables and figures follow and we indicate where the significance of relationships changed. There are no changes to the conclusions of the paper. Mass-Adjusted...
Article
Mallarino et al. introduce the African striped mouse, which is being used in a number of fields of research, including animal behavior, evolutionary developmental biology, and chronobiology.
Article
Resting metabolic rate (RMR) influences energy allocation to survival, growth, and reproduction, and significant seasonal changes in RMR have been reported. According to one hypothesis, seasonal changes in RMR are mainly attributable to seasonal changes in ambient temperature (Ta) and food availability. Studies on species from the temperate zone in...
Article
Full-text available
Evolutionary biologists aim to determine why a particular trait evolved. Detailed studies of single species can identify fitness benefits of specific traits and why those traits evolved, but these results might be rather species specific. Thus, to reach general conclusions about which ecological factors favour the evolution of a specific trait, com...
Article
Many species show intraspecific variation in their social organization (IVSO), which means the composition of their social groups can change between solitary living, pair living, or living in groups. Understanding IVSO is important because it demonstrates species resilience to environmental change and can help us to study ultimate and proximate rea...
Article
Boldness, the willingness of individuals to engage in risky behaviour, is one of the most studied personality traits. It has been measured using a variety of tests; however, measuring a behaviour using different assays may lead to a jingle fallacy. The few studies that have attempted to determine whether these different assays are comparable have p...
Article
Strepsirrhines, that is, lemurs, galagos, and lorises, are considered basal primates, making them important to understand the evolution of primate sociality. Apart from some lemurs, they are nocturnal and solitary living, though the view of their sociality nature has changed with field studies being completed. We conducted a review of the primary l...
Article
Full-text available
Long-term studies on rodents have been conducted for longer periods (up to 70 years) and more generations (up to 88 generations) than for most other mammalian taxa. These studies have been instrumental in furthering our understanding of ecophysiology, social systems, and population and community processes. Studies on African striped mice (Rhabdomys...
Article
Full-text available
Cognitive performance is based on brain functions, which have energetic demands and are modulated by physiological parameters such as metabolic hormones. As both environmental demands and environmental energy availability change seasonally, we propose that cognitive performance in free-living animals might also change seasonally due to phenotypic p...
Article
Full-text available
Energy is limited and must be allocated among competing life-history traits. Reproduction is considered one of the most energetically demanding life-history stages. Therefore, the amount of energy an individual invests in reproduction might carry fitness costs through reduced energy allocation to other activities such as health maintenance. We inve...
Article
To maximize their fitness, individuals of one sex can display discrete reproductive phenotypes, called alternative reproductive tactics (ARTs). Individuals following ARTs show behavioural variation, which might result in differences in energy intake and expenditure. However, few studies have compared activity budgets and non-sexual behaviour of ind...
Article
It has often been proposed that bolder, more explorative or more active individuals also have a higher resting metabolic rate (RMR), indicating metabolic costs of these personality types. However, such individuals might often be restless and thus excluded from RMR datasets, leading to a significant sampling bias. We tested (1) whether such a bias o...