Theo C. M. Bakker

Theo C. M. Bakker
Springer Nature

PhD

About

183
Publications
27,617
Reads
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7,545
Citations
Additional affiliations
August 2011 - present
Springer Nature
Position
  • Editor
September 1999 - August 2017
University of Bonn
Position
  • Professor
Description
  • SEE https://tbakker1.wixsite.com/personalsite
July 1988 - August 1999
Universität Bern
Position
  • Assistant and Associate Professor

Publications

Publications (183)
Article
Full-text available
Different environmental conditions may lead to diverse morphological, behavioral and physiological adaptations of different populations of the same species. Lighting conditions, for example, vary vastly especially between aquatic habitats, and have been shown to elicit adaptations. The availability of shortwave ultraviolet (UV) light is especially...
Article
Full-text available
Different environmental conditions may lead to diverse morphological, behavioral and physiological adaptations of different populations of the same species. Lighting conditions, for example, vary vastly especially between aquatic habitats, and have been shown to elicit adaptations. The availability of short-wave ultraviolet (UV) light is especially...
Article
Full-text available
Fish that perform paternal care may increase their fitness by choosing nest sites that enhance survival and development of embryos. We studied nest-site choice with respect to dissolved oxygen concentration and water temperature in males of the three-spined stickleback (Gasterosteus aculea-tus), a small fish species with exclusive male parental car...
Article
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Ultraviolet A (UVA) signals (320-400 nm) are important in mate choice in numerous species. The sensitivity for ultraviolet signals is not only assumed to be costly, but also expected to be a function of the prevailing ecological conditions. Generally, those signals are favored by selection that efficiently reach the receiver. A decisive factor for...
Article
Full-text available
Ultraviolet (UV) A signals (320–400 nm) are important in mate choice in numerous species. The sensitivity for UV signals is not only assumed to be costly, but also expected to be a function of the prevailing ecological conditions. Generally, those signals are favored by selection that efficiently reach the receiver. A decisive factor for color sign...
Article
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Vertebrate cellular immunity displays substantial variation among taxa and environments. Hematological parameters such as white blood-cell counts have emerged as a valuable tool to understand this variation by assessing the immunological status of individuals. These tools have long revealed that vertebrate cellular immune systems are highly plastic...
Article
Increasing UVB-radiation (UVB) reaching earth's surface following stratospheric ozone depletion is linked to serious consequences for organisms. While studies have focused on direct cytocidal and immunomodulatory effects of UVB, indirect consequences for fitness-related life-history traits are largely unexplored, although knowledge is needed to und...
Article
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Predicting patterns of variation in sexual traits requires understanding how developmental environments influence mate choice. Here, we studied how long-term perceived high predation risk affects mutual mate choice in the cichlid Pelvicachromis taeniatus. From hatching onwards, fish were exposed regularly to either conspecific alarm cues signalling...
Article
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High predation risk during development induces phenotypic changes in animals. However, little is known about how these plastic responses affect signalling and competitiveness during contests. Herein, we have studied the consequences of anti-predator plasticity during the intra-sexual competition of Pelvicachromis taeniatus, a cichlid fish with mutu...
Article
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Parasites with complex life cycles often alter the phenotypic appearance of their intermediate hosts in order to facilitate ingestion by the final host. However, such manipulation can be costly as it might increase ingestion by less suitable or dead-end hosts as well. Species-specific parasitic manipulation is a way to enhance the transmission to s...
Article
Spatial orientation is an important skill as it improves, for example, foraging, localisation of recourses, predator avoidance or navigation. Habitat complexity positively affects spatial abilities in various fish species with a more complex environment promoting learning ability. However, to what extent a complex social environment affects cogniti...
Article
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Organisms inhabiting shallow aquatic habitats currently experience increasing levels of solar ultraviolet B radiation (UVB). UVB causes damage on cellular and molecular levels and can affect associated life-history traits either through direct exposure or indirectly through oxidative stress generation. We examined UVB effects on pre- and post-matin...
Article
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Fishes show a great diversity of mating systems and fertilization mechanisms. This diversity creates an enormous potential for sperm competition. Typically, monogamous species face a low risk of sperm competition and invest less into sperm, and thus show smaller relative testis mass compared to polygamous species with high sperm competition. In cic...
Article
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In many species, males signal quality with elaborate traits, but females often show inter-individual variation in preference for these traits. Choosing a mate requires multiple cognitive steps; therefore cognitive style (how an individual processes information) likely influences the perception of sexual signals and ability to choose a high-quality...
Article
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Group living is widespread across animal taxa, incurring benefits such as increased foraging efficiency or an enhanced chance of surviving a predator's attack. The chances of escaping a predator are often lower for odd‐looking individuals, as these are detected at a higher rate than uniform looking group members. While this “oddity effect” shall op...
Article
Group living reduces individual predation risk most effectively when group members are behaviorally and phenotypically similar. Group preferences are influenced by the individual, the members of the shoal, and the environmental conditions. While shoaling behavior has been studied extensively in the threespine stickleback (Gasterosteus aculeatus), i...
Article
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The ability of organisms to plastically respond to changing environments is well studied. However, variation in phenotypic plasticity during ontogeny is less well understood despite its relevance of being an important source of phenotypic variation in nature. Here, we comprehensively study ontogenetic variation in morphological antipredator plastic...
Article
The ability to compete with conspecifics and to adequately respond to visual stimuli of group mates are important prerequisites for profiting from group benefits such as confusion of predators and greater efficiency in acquiring food. By impairing their host’s physical abilities or making the host conspicuous, even non-contagious parasites that do...
Article
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With ongoing environmental change, ultraviolet-B radiation (UVB) reaching the Earth’s surface has increased over recent decades with consequences for terrestrial and also aquatic ecosystems. Despite evidence for direct physiological and immunological responses of aquatic animals following enhanced UVB exposure, studies investigating indirect impact...
Article
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Ultraviolet-B radiation (UVB) reaching the earth's surface has increased due to human-caused stratospheric ozone depletion. Whereas the harmful effects of UVB on aquatic organisms are well studied at the molecular and cellular level, recent studies have also begun to address behavioural changes caused by sublethal amounts of UVB. However, the behav...
Article
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Parasites with complex life cycles often change intermediate host traits in order to enhance their transmission to the next host. Acanthocephalans are excellent examples of such parasitic manipulation. Here, we summarise evidence for adaptive parasitic manipulation in this group, provide a comprehensive overview of intermediate host traits affected...
Article
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There is a need for rapid and reliable molecular sexing of three-spined sticklebacks, Gasterosteus aculeatus, the supermodel species for evolutionary biology. A DNA region at the 5' end of the sex-linked microsatellite Gac4202 was sequenced for the X chromosome of six females and the Y chromosome of five males from three populations. The Y chromoso...
Article
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Inbreeding and ageing can affect characteristics of reproductive physiology, influencing an individual’s fecundity, fertility, and thus fitness. The effects of inbreeding and age are expected to depend on several factors such as inbreeding history of a population, lifespan, or environmental influences. Here, we investigated the impact of inbreeding...
Article
Full-text available
Inbreeding and ageing have substantial impact on an individual’s fitness. Both can lead to an accumulation of deleterious alleles resulting in an addition of effects when inbreeding and age interact. The aim of this study was to investigate the separate and simultaneous effects of both factors on primary reproductive traits in females of the West A...
Article
Full-text available
Predation is an important but often fluctuating selection factor for prey animals. Accordingly, individuals plastically adopt antipredator strategies in response to current predation risk. Recently, it was proposed that predation risk also plastically induces neophobia (an antipredator response towards novel cues). Previous studies, however, do not...
Article
The genetic diversity and population structure of a parasite with a complex life cycle generally depends on the dispersal by its most motile host. Given that high gene flow is assumed to hinder local adaptation, this can impose significant constraints on a parasite's potential to adapt to local environmental conditions, intermediate host population...
Article
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Analysing spatial differences among macroparasite communities is an important tool in the study of host–parasite interactions. Identifying patterns can shed light on the underlying causes of heterogeneity of parasite distribution and help to better understand ecological constraints and the relative importance of host and parasite adaptations. In th...
Article
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Body coloration and color patterns are ubiquitous throughout the animal kingdom and vary between and within species. Recent studies have dealt with individual dynamics of various aspects of coloration, as it is in many cases a flexible trait and changes in color expression may be context-dependent. During the reproductive phase, temporal changes of...
Article
Social-rearing environment has profound effects on behaviour, physiology and development. A complex social environment enhances an individual's social skills and competence in many animal taxa. Consequently, complete social deprivation seriously impairs various aspects of behaviour, development, brain function and hormone levels. Although sexual se...
Article
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Color signals, including ultraviolet (UV) signals, are widespread throughout the animal kingdom and color changes can be influenced by reproductive and motivational state. However, studies on dynamic changes of UV signals are scarce. Three spine sticklebacks (Gasterosteus aculeatus) that show intraspecific UV communication were used to study dynami...
Article
Full-text available
Please note that "three spine" should be read as "threespine" throughout the manuscript. We are very sorry for this mistake caused by the publisher. Color signals, including ultraviolet (UV) signals, are widespread throughout the animal kingdom and color changes can be influenced by reproductive and motivational state. However, studies on dynamic...
Article
Full-text available
In polyandrous mating systems, male reproductive success depends on both mate-acquisition traits (precopulatory) and sperm competitive abilities (postcopulatory). Empirical data on the interaction between these traits are inconsistent; revealing positive, negative or no relationships. It is generally expected that the investment in pre- and postcop...
Article
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Group living is widespread in animals. In nature, groups usually not only differ in phenotypic characteristics but also in the social relationships among group members. Theory predicts that individuals adjusting their shoaling decisions—to join certain groups or not—based on social criteria, such as familiarity or genetic relatedness, can increase...
Article
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Individuals have to respond simultaneously to different environmental factors often making trade-offs between conflicting demands necessary. Many freshwater ecosystems are resource-limited and both intra- and interspecific competitiveness is a common requirement to gain and defend resources necessary for reproduction. Although predation risk is an...
Article
Animals usually benefit from joining groups, but joining a group can also come at a cost when members expose themselves to competition and the risk of contracting a contagious disease. Therefore, individuals are expected to adjust grouping behaviour to the ecological circumstances, their own competitiveness and the composition of the group. Here, w...
Article
Grouping is a widespread phenomenon in the animal kingdom and the decision to join a group is a function of individual and environmental conditions, meaning that any advantages and disadvantages have to be pondered constantly. Shoaling decisions in fishes are communicated via a variety of factors, such as colour signals, amongst other ultraviolet (...
Article
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The ability to discriminate between different quantities is widespread throughout the animal kingdom, and the underlying mechanisms of quantity discrimination are currently intensely discussed. In contrast, questions elucidating the limits of quantity estimation received rather little attention so far. Here, we examined fine-tuned quantity estimati...
Article
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Social aggregations occur in many different animal taxa and mainly result from non-random assortment. Investigating factors that shape and maintain the composition of social aggregations are among others a main topic for understanding ecological speciation processes. Aggregation decisions are mediated by olfactory and visual cues, which in many ani...
Article
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Background Mating between close relatives often leads to a reduction of an individual’s fitness, due to an increased expression of deleterious alleles. Thus, in many animal taxa pre- as well as postcopulatory inbreeding avoidance mechanisms have evolved. An increased risk of inbreeding and hence a loss of genetic variation may occur during founder...
Article
Full-text available
Body coloration and color patterns are ubiquitous throughout the animal kingdom and vary between and within species. Recent studies have dealt with individual dynamics of various aspects of coloration, as it is in many cases a flexible trait and changes in color expression may be context-dependent. During the reproductive phase, temporal changes of...
Article
Full-text available
The ability to recognize conspecifics is indispensible for differential treatment of particular individuals in social contexts like grouping behavior. The advantages of grouping are multifarious, and there exist numerous additional benefits of joining aggregations of conspecifics. Recognition is based on different signals and transmitted via multip...
Article
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Acute and long-term temperature changes caused by global warming could lead to severe ecological and physiological consequences for aquatic organisms. This might be reflected in a higher mortality rate or a reduced hatching success but elevated temperatures might also lead to accelerated growth and egg development due to higher metabolic rates. The...
Article
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Some theoretical models of sperm competition make the assumption that in fish species with external fertilisation, sperm length relates positively to swimming speed at the expense of sperm longevity. Few studies have tested this assumption. We used the three-spined stickleback, Gasterosteus aculeatus L., to study functional sperm morphology. In thi...
Article
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Kin discrimination in nepotistic as well as in sexual contexts is widespread in animals including humans. However, the underlying mechanisms of kin discrimination are assumed to vary between species and-within species-between contexts. During solitary life stages, kin recognition based on social learning is assumed to be less reliable because kin t...
Article
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The process of ageing is associated with negative effects of mutations acting late in life, which range from those affecting cells to those affecting the whole organism. In many animal taxa, the deterioration of the phenotype with age also affects traits such as males' primary and secondary sexual characteristics. In three-spined sticklebacks (Gast...
Article
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Recent studies have revealed that sexually selected traits may signal sperm quality and hence male fertilisation ability. There is also evidence that the expression of male sexual ornamentation and associated sperm characteristics depend on an individual's ability to cope with oxidative stress. Carotenoids are known for their antioxidant properties...
Article
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Article
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Exposure to enhanced levels of ambient ultraviolet (UV) radiation (UVR) can have adverse effects on aquatic organisms including damage at the cellular and molecular level and impairment of development, fecundity and survival. Much research has been conducted on the role of the harmful UVB radiation. However, due to its greater penetration in water...