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News Article | May 17, 2017
Site: www.sciencedaily.com

Genetically identical Amazon mollies raised individually and under identical environmental conditions, nevertheless develop different personality types. Additionally, increasing the opportunity for social interactions early in life appears to have no influence of the magnitude of personality variation. These results of a recent study by the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) shed a new light on the question of which factors are responsible for the individuality of vertebrate animals. Both the genetics and the environment have an effect on the individual behavior of animals -- or at least that is the common doctrine. But what happens when individuals whose genes are identical are raised in environments that are identical -- do they then develop identical behavioral patterns? A team headed by IGB researchers Dr. David Bierbach and Dr. Kate Laskowski investigated this question in a study, which was published in the journal Nature Communications. The IGB scientists were able to show for the first time that genetically identical animals develop different types of personality even if they are raised under almost identical conditions. The IGB team used the Amazon molly, a livebearing Poecilid species. These animals are natural clones, meaning all the offspring of one mother have exactly the same genetic material. Newborn Amazon mollies were placed in three different experimental setups: In the first treatment the animals were kept individually from and under identical conditions from birth. In two other treatments the fish lived for one or three weeks, respectively, in groups of four individuals and were then later separated. After seven weeks, the researchers examined all the Amazon mollies to determine whether and how the individual fish differed in activity and exploratory behavior. "We were very surprised to find such distinct personality differences in genetically identical animals that grew up under nearly equal environmental conditions," says Dr. David Bierbach, behavioral ecologist at the IGB and one of the two leading authors of the study. The fish which developed initially in small groups, also showed behavioral differences of nearly the same degree -- no matter whether the development phase with social interactions lasted one or three weeks. Study indicates that individuality may be inevitable "Our results suggest that other factors must influence the development of personality in a more substantial way than previously thought: potentially minute differences in environmental conditions, which are impossible to remove completely from any experiment, or potentially epigenetic processes, i.e. random changes of chromosomes and gene functions. Altogether our results suggests that these factors deserve closer inspection as causes of personality variation in future work," explains behavioral ecologist Dr. Kate Laskowski. The IGB study suggests that the development of individuality in vertebrate animals may be an inevitable and ultimately unpredictable result of the developmental process.


The Amazon molly reproduces clonally so that each offspring is an exact genetic copy of her mother. Credit: Bierbach / IGB Genetically identical Amazon mollies raised individually and under identical environmental conditions, nevertheless develop different personality types. Additionally, increasing the opportunity for social interactions early in life appears to have no influence of the magnitude of personality variation. These results of a recent study by the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) shed a new light on the question of which factors are responsible for the individuality of vertebrate animals. Both the genetics and the environment have an effect on the individual behavior of animals – or at least that is the common doctrine. But what happens when individuals whose genes are identical are raised in environments that are identical – do they then develop identical behavioral patterns? A team headed by IGB researchers Dr. David Bierbach and Dr. Kate Laskowski investigated this question in a study, which was published on 17th of May 2017 in the journal Nature Communications. The IGB scientists were able to show for the first time that genetically identical animals develop different types of personality even if they are raised under almost identical conditions. The IGB team used the Amazon molly, a livebearing Poecilid species. These animals are natural clones, meaning all the offspring of one mother have exactly the same genetic material. Newborn Amazon mollies were placed in three different experimental setups: In the first treatment the animals were kept individually from and under identical conditions from birth. In two other treatments the fish lived for one or three weeks, respectively, in groups of four individuals and were then later separated. After seven weeks, the researchers examined all the Amazon mollies to determine whether and how the individual fish differed in activity and exploratory behavior. "We were very surprised to find such distinct personality differences in genetically identical animals that grew up under nearly equal environmental conditions," says Dr. David Bierbach, behavioral ecologist at the IGB and one of the two leading authors of the study. The fish which developed initially in small groups, also showed behavioral differences of nearly the same degree - no matter whether the development phase with social interactions lasted one or three weeks. Study indicates that individuality may be inevitable "Our results suggest that other factors must influence the development of personality in a more substantial way than previously thought: potentially minute differences in environmental conditions, which are impossible to remove completely from any experiment, or potentially epigenetic processes, i.e. random changes of chromosomes and gene functions. Altogether our results suggests that these factors deserve closer inspection as causes of personality variation in future work," explains behavioral ecologist Dr. Kate Laskowski. The IGB study suggests that the development of individuality in vertebrate animals may be an inevitable and ultimately unpredictable result of the developmental process. Explore further: People could be genetically predisposed to social media use More information: David Bierbach et al. Behavioural individuality in clonal fish arises despite near-identical rearing conditions, Nature Communications (2017). DOI: 10.1038/ncomms15361


News Article | May 16, 2017
Site: phys.org

Cohort after cohort, fishing typically removes large fish from the population and can lead to rapid evolutionary changes in exploited fish populations. A new study from the University of Turku, Finland, shows that removing the largest individuals from the population can lead to massive gene expression changes in an experimentally exploited fish population. The study was funded by the Academy of Finland. During the last two decades, there has been a lot of discussion on size-selective fishing causing genetic changes in exploited populations in contemporary timescales. Now, researchers have shown that fishing can cause expression changes in thousands of genes and that these changes can at least partly be associated with changes at DNA level. "Removing the largest individuals from the experimentally exploited populations induced differences in the expression of more than 4,000 genes after five generations of size-selective harvesting," says postdoctoral researcher Silva Uusi-Heikkilä from the University of Turku. The harvesting experiment was done in collaboration between the University of Turku and the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin. For five generations, experimental zebrafish populations were harvested by using two harvesting strategies: removing the largest individuals and removing individuals randomly with respect to body size. After harvesting, the populations were allowed to recover for six generations. "Changes in gene expression help fish to adapt to different selective pressure," Uusi-Heikkilä says. "It's noteworthy, however, that the differences in expression pattern between the harvest treatments remained after the recovery." In addition to the changes in gene expression, the expression variance was also affected by fishing: fishing decreased the variance. Gene expression variation can be important because it may help fish to adapt to changes in the environment and the climate. "After the recovery period, the gene expression variance increased but only in randomly harvested fish. The variance continued to decrease among fish where the largest individuals had been removed," Uusi-Heikkilä says. Reduced variation caused by size-selective harvesting in exploited populations can slow down the recovery. "Moderate fishing pressure combined with protection of large individuals may advance the recovery of fish populations." More information: Silva Uusi-Heikkilä et al. Rapid, broad-scale gene expression evolution in experimentally harvested fish populations, Molecular Ecology (2017). DOI: 10.1111/mec.14179


News Article | May 16, 2017
Site: www.eurekalert.org

Cohort after cohort, fishing typically removes large fish from the population and can lead to rapid evolutionary changes in exploited fish populations. A new study from the University of Turku, Finland, shows that removing the largest individuals from the population can lead to massive gene expression changes in an experimentally exploited fish population. The study was funded by the Academy of Finland. During the last two decades, there has been a lot of discussion on size-selective fishing causing genetic changes in exploited populations in contemporary timescales. Now, researchers have shown that fishing can cause expression changes in thousands of genes and that these changes can at least partly be associated with changes at DNA level. "Removing the largest individuals from the experimentally exploited populations induced differences in the expression of more than 4,000 genes after five generations of size-selective harvesting," says postdoctoral researcher Silva Uusi-Heikkilä from the University of Turku. The harvesting experiment was done in collaboration between the University of Turku and the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin. For five generations, experimental zebrafish populations were harvested by using two harvesting strategies: removing the largest individuals and removing individuals randomly with respect to body size. After harvesting, the populations were allowed to recover for six generations. "Changes in gene expression help fish to adapt to different selective pressure," Uusi-Heikkilä says. "It's noteworthy, however, that the differences in expression pattern between the harvest treatments remained after the recovery." In addition to the changes in gene expression, the expression variance was also affected by fishing: fishing decreased the variance. Gene expression variation can be important because it may help fish to adapt to changes in the environment and the climate. "After the recovery period, the gene expression variance increased but only in randomly harvested fish. The variance continued to decrease among fish where the largest individuals had been removed," Uusi-Heikkilä says. Reduced variation caused by size-selective harvesting in exploited populations can slow down the recovery. "Moderate fishing pressure combined with protection of large individuals may advance the recovery of fish populations."


News Article | May 16, 2017
Site: www.sciencedaily.com

Cohort after cohort, fishing typically removes large fish from the population and can lead to rapid evolutionary changes in exploited fish populations. A new study from the University of Turku, Finland, shows that removing the largest individuals from the population can lead to massive gene expression changes in an experimentally exploited fish population. The study was funded by the Academy of Finland. During the last two decades, there has been a lot of discussion on size-selective fishing causing genetic changes in exploited populations in contemporary timescales. Now, researchers have shown that fishing can cause expression changes in thousands of genes and that these changes can at least partly be associated with changes at DNA level. "Removing the largest individuals from the experimentally exploited populations induced differences in the expression of more than 4,000 genes after five generations of size-selective harvesting," says postdoctoral researcher Silva Uusi-Heikkilä from the University of Turku. The harvesting experiment was done in collaboration between the University of Turku and the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin. For five generations, experimental zebrafish populations were harvested by using two harvesting strategies: removing the largest individuals and removing individuals randomly with respect to body size. After harvesting, the populations were allowed to recover for six generations. "Changes in gene expression help fish to adapt to different selective pressure," Uusi-Heikkilä says. "It's noteworthy, however, that the differences in expression pattern between the harvest treatments remained after the recovery." In addition to the changes in gene expression, the expression variance was also affected by fishing: fishing decreased the variance. Gene expression variation can be important because it may help fish to adapt to changes in the environment and the climate. "After the recovery period, the gene expression variance increased but only in randomly harvested fish. The variance continued to decrease among fish where the largest individuals had been removed," Uusi-Heikkilä says. Reduced variation caused by size-selective harvesting in exploited populations can slow down the recovery. "Moderate fishing pressure combined with protection of large individuals may advance the recovery of fish populations."


Wolf M.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Weissing F.J.,University of Groningen
Trends in Ecology and Evolution | Year: 2012

Personality differences are a widespread phenomenon throughout the animal kingdom. Past research has focused on the characterization of such differences and a quest for their proximate and ultimate causation. However, the consequences of these differences for ecology and evolution received much less attention. Here, we strive to fill this gap by providing a comprehensive inventory of the potential implications of personality differences, ranging from population growth and persistence to species interactions and community dynamics, and covering issues such as social evolution, the speed of evolution, evolvability, and speciation. The emerging picture strongly suggests that personality differences matter for ecological and evolutionary processes (and their interaction) and, thus, should be considered a key dimension of ecologically and evolutionarily relevant intraspecific variation. © 2012 Elsevier Ltd.


Kalinkat G.,Leibniz Institute of Freshwater Ecology and Inland Fisheries
Journal of Animal Ecology | Year: 2014

The consumption rate of the crab Panopeus herbstii feeding on the mussel Brachidontes exustus depends on predator and prey body size as well as the predator individual activity level. Photo credit: Kathryn Levasseur. Toscano, B.J. & Griffen,B.D. (2014) Trait-mediated functional responses: predator behavioural type mediates prey consumption. Journal of Animal Ecology, 83, 1469-1477. While the concept of consistent behavioural differences among individuals of the same population has gained a lot of scientific attention over the last decade, its implementation into a community context with a focus on species-level interactions is still in its infancy. In their study on the effects of animal personalities on predator-prey functional responses of mussel-eating crabs, Toscano & Griffen (2014) introduce a promising avenue for future research synthesizing concepts and ideas from animal behaviour and food web ecology. More precisely, by showing that the interplay of animal personalities and predator and prey body sizes significantly alters the outcome of predator-prey interactions, this study provides important evidence that the concept of animal personalities needs greater consideration if we want to refine and improve current models of predator-prey interactions and the impact of individual-level variation on quantitative food-web dynamics. © 2014 The Author.


Sukhodolov A.N.,Leibniz Institute of Freshwater Ecology and Inland Fisheries
Water Resources Research | Year: 2012

The effects of channel curvature on turbulent flow in meander bends have been the main focus of extensive experimental and theoretical research hitherto. This paper is motivated by growing evidence that riffle-pool morphology in bends can also have strong implications for the flow structure. Flow in a bend of a lowland river with a shallow riffle and a deep pool is examined in this study by using the results of field measurements. In the study, reach flow is quasi-uniform in the riffle. In the pool, two layers compose the vertical structure of flow with a quasi-uniform flow near the riverbed. The upper layer is affected by lateral advection of fluid with low momentum from the inner bank that results in reduced tangential velocities, submergence of velocity maximum, and almost zero shear stress. Bed shear stress is estimated from the local profiles of turbulent shear stress and is shown to comply with values computed with the modified length scale. The maximum bed shear stress is situated in the riffle while theoretical considerations based on the effect of curvature suggest the pool as the most probable location of the maximum. This fact supports the hypothesis that the effects of riffle-pool morphology are dominant for the study reach. The study contributes to the clarification of up-scaling results from laboratory experiments to natural rivers by providing a detailed analysis of turbulence profiles. It shows that parameters of turbulence profiles, scaled with the proper velocity and length scales, are similar to those reported by previous experimental studies for open-channel flow. © 2012 by the American Geophysical Union.


Grossart H.-P.,Leibniz Institute of Freshwater Ecology and Inland Fisheries
Environmental Microbiology Reports | Year: 2010

In recent years, microbial ecology has developed from a peripheral discipline into a central field of microbiology. This change in state and perception is mainly driven by a rapid development of methods applied in the manifold fields related to microbial ecology. In biogeochemistry, for example, the use of high-resolution techniques such as FT-ICR-MS (Fourier transform ion cyclotron mass spectroscopy) has uncovered an enormous diversity and complexity of natural organic matter produced or degraded microbially either in dissolved or particulate forms. On the other hand, the introduction of highthroughput sequencing methods, such as 454 pyrosequencing, in combination with advances in bioinformatics allows for studying the bacterial diversity in natural samples circumventing cultivation dependent approaches. These new molecular tools enable in depth studies on single-cell genomes, distinct populations or even metacommunities. In combination with metatranscriptome and proteome studies it is for the first time possible to simultaneously unravel the structure and function of complex communities in situ. These techniquederived findings have, on the one hand, dramatically increased our knowledge on the vast diversity and complexity of bacterial habitats and, on the other hand, on phylogentic diversity and physiological responses of natural bacterial communities to their environment. However, until now microbial ecology is lacking an ecologically relevant species definition and useful tools for the identification of ecologically coherent taxa. Studies on intra- and interspecies interactions even with higher organisms demonstrate that bacteria can rapidly adapt to temporal and spatial changes in their environment. Aquatic bacteria have optimized and dramatically expanded their living space by efficient exploitation of organic matter point sources such as particles/aggregates and higher organisms. Although it is evident that particles/aggregates and organisms such as phytoplankton are 'hotspots' for microbial growth and transformation processes, it has not affected sampling strategies of aquatic microbial ecologists, who often focus solely on the free-living bacterial fractions and a priori exclude higher organisms by nonrepresentative water sampling. Therefore, aquatic microbial ecologists have largely overlooked the fact that many aquatic bacteria may possess a complex lifestyle and frequently alternate between a free-living and a surface-associated stage. Here, I propose that modern concepts in aquatic microbial ecology should take into account the high chemical diversity and spatio-temporal variability of the bacterial environment. Interactions of aquatic bacteria with surfaces including living organisms are the key to understanding their physiological adaptations and population dynamics, as well as their contribution to biogeochemical cycles. New sampling strategies and theoretical concepts are needed in aquatic microbial ecology to access the whole spectrum of bacterial lifestyles and their ecological and evolutionary consequences. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.


Mehner T.,Leibniz Institute of Freshwater Ecology and Inland Fisheries
Freshwater Biology | Year: 2012

Diel vertical migrations (DVM) are typical for many cold-water fish species such as Pacific salmons (Oncorhynchus spp.) and coregonids (Coregonus spp.) inhabiting deep lakes. A comprehensive recent overview of DVM in freshwater fish has not been available, however. The main proximate trigger of DVM in freshwater fish is the diel change in light intensity, with declining illumination at dusk triggering the ascent and the increase at dawn triggering the descent. Additional proximate cues are hydrostatic pressure and water temperature, which may guide fish into particular water layers at night. Ultimate causes of DVM encompass bioenergetics efficiency, feeding opportunities and predator avoidance. None of these factors alone can explain the DVM in all cases. Multi-factorial hypotheses, such as the 'antipredation window' combined with the thermal niche hypothesis, are more likely to explain DVM. It is suggested that planktivorous fish move within a layer sufficiently well illuminated to capture zooplankton, but too dark for predators to feed upon the migrating fish. In complete darkness, fish seek layers with a temperature that optimises bioenergetics efficiency. The strength of each factor may differ from lake to lake, and hence system-specific individual analyses are needed. Mechanistic details that are still poorly explored are the costs of buoyancy regulation and migration, the critical light thresholds for feeding of planktivorous and piscivorous fish, and predator assessment by (and size-dependent predation risk of) the prey fish. A comprehensive understanding of the adaptive value of DVM can be attained only if the behaviour of individual fish within migrating populations is explicitly taken into account. Size, condition and reproductive value differ between individuals, suggesting that migrating populations should split into migrants and non-migrants for whom the balance between mortality risk and growth rate can differ. There is increasing evidence for this type of partial DVM within populations. Whereas patterns of DVM are well documented, the evolution of DVM is still only poorly understood. Because experimental approaches at realistic natural scales remain difficult, a combination of comprehensive data sets with modelling is likely to resolve the relative importance of different proximate and ultimate causes behind DVM in fish. © 2012 Blackwell Publishing Ltd.

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