| 1. |
- Legrand, Delphine, et al.
(författare)
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The Metatron : an experimental system to study dispersal and metaecosystems for terrestrial organisms
- 2012
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Ingår i: Nature Methods. - 1548-7091 .- 1548-7105. ; 9:8, s. 828-
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Tidskriftsartikel (refereegranskat)abstract
- Dispersal of organisms generates gene flow between populations. Identifying factors that influence dispersal will help predict how species will cope with rapid environmental change. We developed an innovative infrastructure, the Metatron, composed of 48 interconnected patches, designed for the study of terrestrial organism movement as a model for dispersal. Corridors between patches can be flexibly open or closed. Temperature, humidity and illuminance can be independently controlled within each patch. The modularity and adaptability of the Metatron provide the opportunity for robust experimental design for the study of 'meta-systems'. We describe a pilot experiment on populations of the butterfly Pieris brassicae and the lizard Zootoca vivipara in the Metatron. Both species survived and showed both disperser and resident phenotypes. The Metatron offers the opportunity to test theoretical models in spatial ecology.
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| 2. |
- Zajitschek, Felix, et al.
(författare)
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Evolution Under Dietary Restriction Decouples Survival From Fecundity in Drosophila melanogaster Females
- 2019
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Ingår i: The journals of gerontology. Series A, Biological sciences and medical sciences. - : Oxford University Press (OUP). - 1079-5006 .- 1758-535X. ; 74:10, s. 1542-1548
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Tidskriftsartikel (refereegranskat)abstract
- One of the key tenets of life-history theory is that reproduction and survival are linked and that they trade-off with each other. When dietary resources are limited, reduced reproduction with a concomitant increase in survival is commonly observed. It is often hypothesized that this dietary restriction effect results from strategically reduced investment in reproduction in favor of somatic maintenance to survive starvation periods until resources become plentiful again. We used experimental evolution to test this "waiting-for-the-good-times" hypothesis, which predicts that selection under sustained dietary restriction will favor increased investment in reproduction at the cost of survival because "good-times" never come. We assayed fecundity and survival of female Drosophila melanogaster fruit flies that had evolved for 50 generations on three different diets varying in protein content-low (classic dietary restriction diet), standard, and high-in a full-factorial design. High-diet females evolved overall increased fecundity but showed reduced survival on low and standard diets. Low-diet females evolved reduced survival on low diet without corresponding increase in reproduction. In general, there was little correspondence between the evolution of survival and fecundity across all dietary regimes. Our results contradict the hypothesis that resource reallocation between fecundity and somatic maintenance underpins life span extension under dietary restriction.
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| 3. |
- Zajitschek, Felix, et al.
(författare)
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Evolution under dietary restriction increases male reproductive performance without survival cost
- 2016
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : ROYAL SOC. - 0962-8452 .- 1471-2954. ; 283:1825, s. 20152726-
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Tidskriftsartikel (refereegranskat)abstract
- Dietary restriction (DR), a reduction in nutrient intake without malnutrition, is the most reproducible way to extend lifespan in a wide range of organisms across the tree of life, yet the evolutionary underpinnings of the DR effect on lifespan are still widely debated. The leading theory suggests that this effect is adaptive and results from reallocation of resources from reproduction to somatic maintenance, in order to survive periods of famine in nature. However, such response would cease to be adaptive when DR is chronic and animals are selected to allocate more resources to reproduction. Nevertheless, chronic DR can also increase the strength of selection resulting in the evolution of more robust genotypes. We evolved Drosophila melanogaster fruit flies on DR, standard and high adult diets in replicate populations with overlapping generations. After approximately 25 generations of experimental evolution, male DR flies had higher fitness than males from standard and high populations. Strikingly, this increase in reproductive success did not come at a cost to survival. Our results suggest that sustained DR selects for more robust male genotypes that are overall better in converting resources into energy, which they allocate mostly to reproduction.
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| 4. |
- Zajitschek, Felix, et al.
(författare)
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Interactive effects of sex, social environment, dietary restriction, and methionine on survival and reproduction in fruit flies
- 2013
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Ingår i: Age (Omaha). - : Springer. - 0161-9152 .- 1574-4647. ; 35:4, s. 1193-1204
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Tidskriftsartikel (refereegranskat)abstract
- For the evolution of life histories, the trade-off between survival and reproduction is fundamental. Because sexes optimize fitness in different ways, this trade-off is expected to be resolved differently by males and females. Consequently, the sexes are predicted to respond differently to changes in resource availability. In fruit flies, research on dietary restriction has focused largely on females maintained in the absence of males, thereby neglecting sexual interactions that affect reproductive behavior of both sexes under more natural conditions. Here, we tested for the interactive effects of diet (40, 60, 100, and 300 % of standard yeast concentrations) and social environment (separate-sex vs. mixed-sex groups) on male and female Drosophila melanogaster life histories. Additionally, we evaluated the essential amino acid methionine as an agent that can uncouple the survival-reproduction trade-off. We show sex differences in the effect of social environment on survival patterns, but not on reproductive fitness. In females, yeast had a positive effect on reproduction and a negative effect on survival. In males, yeast had a negative effect on reproduction and the effect on survival depended on the social environment. Methionine reduced survival, but had no effect on reproduction. Our findings highlight the need to include both sexes and to vary social environments in research programs aimed at lifespan extension and call for further evaluation of the fecundity-restoring effect of methionine.
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| 5. |
- Zajitschek, Susanne, et al.
(författare)
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Paternal personality and social status influence offspring activity in zebrafish
- 2017
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Evidence for the transmission of non-genetic information from father to offspring is rapidly accumulating. While the impact of chemical and physical factors such as toxins or diet on the fitness of the parents and their offspring have been studied extensively, the importance of behavioural and social circumstances has only recently been recognised. Behavioural traits such as personality characteristics can be relatively stable, and partly comprise a genetic component but we know little about the non-genetic transmission of plastic behavioural traits from parents to offspring. We investigated the relative effect of personality and of social dominance as indicators at the opposite ends of the plasticity range on offspring behaviour in the zebrafish (Danio rerio). We assessed male boldness, a behavioural trait that has previously been shown previously to possess genetic underpinnings, and experimentally manipulated male social status to assess the association between the two types of behaviour and their correlation with offspring activity. Results: We found a clear interaction between the relatively stable and putative genetic effects based on inherited differences in personality and the experimentally induced epigenetic effects from changes in the social status of the father on offspring activity. Conclusions: Our study shows that offspring behaviour is determined by a combination of paternal personality traits and on-genetic effects derived from the social status of the father.
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| 6. |
- Zajitschek, Susanne R. K., et al.
(författare)
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The effect of coloration and temperature on sprint performance in male and female wall lizards
- 2012
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 107:3, s. 573-582
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypic coloration in animals is often expected to have a signalling function, but it may also evolve as a correlated trait that reflects life-history strategy, social strategy, or ecological divergence. Wall lizards (Podarcis muralis) exhibit substantial colour variation, with both males and females being red, white, yellow, or a mixture of these colours. However, the biological significance of these colour morphs remains unknown. Here we investigate the relationship between coloration and temperature-dependent locomotor performance in an attempt to identify the adaptive significance of colour variation in this species. We investigate the maximum sprint speed of males and females of each of these colour morphs across seven different temperatures, using general additive mixed models (GAMMs). We predicted that the different sexes and colour phenotypes would exhibit differences in sprint speed performance, potentially indicating a correlation between coloration and adaptation into different ecological niches. We found no difference in performance of the discrete colour morphs, but amongst individuals that exhibited red coloration, those with a greater percentage of red were slower than those with less red coloration. This suggests a trade-off between red coloration and high sprint performance in this species. Furthermore, larger animals performed better, independent of colour and sex. Finally, we found no relative or absolute difference between males and females in their sprint performance. Taken together, our results suggest that there is no sex-specific or colour morph-specific differentiation in the use of microhabitats in this species.
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| 7. |
- Zajitschek, Susanne R. K., et al.
(författare)
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The importance of habitat resistance for movement decisions in the common lizard, Lacerta vivipara
- 2012
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Ingår i: BMC Ecology. - : Springer Science and Business Media LLC. - 1472-6785. ; 12, s. 13-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Movement behaviour can be influenced by a multitude of biotic and abiotic factors. Here, we investigate the speed of movement in relation to environmental and individual phenotypic properties in subadult common lizards (Lacerta vivipara). We aim to disentangle the importance of substrate, cover, humidity, basking opportunity and individual phenotype on moving tendencies in 12 treatment combinations, at which each lizard was tested.Results: We find that movement behaviour depends on the starting conditions, the physical properties of the dispersal corridor, and on the individuals' phenotype. Specifically, the presence of cover and substrate providing suitable traction in the corridor had positive effects on individual movement decisions. Additionally, we find high phenotypic variation in the propensity to move dependent on the presence of cover. Individual back patterns also strongly affected movement decisions in interaction with the physical properties of the dispersal corridor.Conclusions: Our results highlight the importance of understanding the habitat resistance for movement patterns, with humid habitats with covering vegetation providing the best conditions to initiate movement in the common lizard. In addition, population effects, differences in back pattern phenotype and individual plasticity were identified as key parameters influencing movement behaviour.
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| 8. |
- Zajitschek, Susanne, et al.
(författare)
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Short-term variation in sperm competition causes sperm-mediated epigenetic effects on early offspring performance in the zebrafish
- 2014
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 281:1785, s. 20140422-
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Tidskriftsartikel (refereegranskat)abstract
- The inheritance of non-genetic factors is increasingly seen to play a major role in ecology and evolution. While the causes and consequences of epigenetic effects transmitted from the mother to the offspring have received ample attention, much less is known about how variation in the condition of the father affects the offspring. Here, we manipulated the intensity of sperm competition experienced by male zebrafish Danio rerio to investigate the potential for sperm-mediated epigenetic effects over a relatively short period of time. We found that the rapid responses of males to varying intensity of sperm competition not only affected sperm traits as shown previously, but also the performance of the resulting offspring. We observed that males exposed to high intensity of sperm competition produced faster swimming and more motile sperm, and sired offspring that hatched over a narrower time frame but exhibited a lower survival rate than males exposed to low intensity of sperm competition. Our results provide striking evidence for short-term paternal effects and the possible fitness consequences of such sperm-mediated non-genetic factors not only for the resulting offspring but also for the female.
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| 9. |
- Alavioon, Ghazal, et al.
(författare)
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Haploid selection within a single ejaculate increases offspring fitness
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; :30, s. 8053-8058
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Tidskriftsartikel (refereegranskat)abstract
- An inescapable consequence of sex in eukaryotes is the evolution of a biphasic life cycle with alternating diploid and haploid phases. The occurrence of selection during the haploid phase can have far-reaching consequences for fundamental evolutionary processes including the rate of adaptation, the extent of inbreeding depression, and the load of deleterious mutations, as well as for applied research into fertilization technology. Although haploid selection is well established in plants, current dogma assumes that in animals, intact fertile sperm within a single ejaculate are equivalent at siring viable offspring. Using the zebrafish Danio rerio, we show that selection on phenotypic variation among intact fertile sperm within an ejaculate affects offspring fitness. Longer-lived sperm sired embryos with increased survival and a reduced number of apoptotic cells, and adult male offspring exhibited higher fitness. The effect on embryo viability was carried over into the second generation without further selection and was equally strong in both sexes. Sperm pools selected by motile phenotypes differed genetically at numerous sites throughout the genome. Our findings clearly link within-ejaculate variation in sperm phenotype to offspring fitness and sperm genotype in a vertebrate and have major implications for adaptive evolution.
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| 10. |
- Kotrschal, Alexander, et al.
(författare)
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Artificial selection on relative brain size in the guppy reveals costs and benefits of evolving a larger brain
- 2013
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 23:2, s. 168-171
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Tidskriftsartikel (refereegranskat)abstract
- The large variation in brain size that exists in the animal kingdom has been suggested to have evolved through the balance between selective advantages of greater cognitive ability and the prohibitively high energy demands of a larger brain (the "expensive-tissue hypothesis" [1]). Despite over a century of research on the evolution of brain size, empirical support for the trade-off between cognitive ability and energetic costs is based exclusively on correlative evidence [2], and the theory remains controversial [3, 4]. Here we provide experimental evidence for costs and benefits of increased brain size. We used artificial selection for large and small brain size relative to body size in a live-bearing fish, the guppy (Poecilia reticulata), and found that relative brain size evolved rapidly in response to divergent selection in both sexes. Large-brained females outperformed small-brained females in a numerical learning assay designed to test cognitive ability. Moreover, large-brained lines, especially males, developed smaller guts, as predicted by the expensive-tissue hypothesis [1], and produced fewer offspring. We propose that the evolution of brain size is mediated by a functional trade-off between increased cognitive ability and reproductive performance and discuss the implications of these findings for vertebrate brain evolution.
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