| 1. |
- Lind, Martin I., Dr, et al.
(författare)
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Experimentally reduced insulin/IGF‐1 signaling in adulthood extends lifespan of parents and improves Darwinian fitness of their offspring
- 2019
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Ingår i: Evolution Letters. - : Oxford University Press (OUP). - 2056-3744. ; 3:2, s. 207-216
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Tidskriftsartikel (refereegranskat)abstract
- Classical theory maintains that ageing evolves via energy trade-offs between reproduction and survival leading to accumulation of unrepaired cellular damage with age. In contrast, the emerging new theory postulates that ageing evolves because of deleterious late-life hyper-function of reproduction-promoting genes leading to excessive biosynthesis in late-life. The hyper-function theory uniquely predicts that optimizing nutrient-sensing molecular signaling in adulthood can simultaneously postpone ageing and increase Darwinian fitness. Here, we show that reducing evolutionarily conserved insulin/IGF-1 nutrient-sensing signaling via daf-2 RNA interference (RNAi) fulfils this prediction in Caenorhabditis elegans nematodes. Long-lived daf-2 RNAi parents showed normal fecundity as self-fertilizing hermaphrodites and improved late-life reproduction when mated to males. Remarkably, the offspring of daf-2 RNAi parents had higher Darwinian fitness across three different genotypes. Thus, reduced nutrient-sensing signaling in adulthood improves both parental longevity and offspring fitness supporting the emerging view that suboptimal gene expression in late-life lies at the heart of ageing.
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| 2. |
- Sekajova, Zuzana
(författare)
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Adaptation and plasticity within and across generations
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The environment is seldom stable but often changes from one state to another and in order to survive and reproduce organisms need to respond to those changes. If the change is fast, genetic adaptations may not evolve quickly enough and organisms must adopt other strategies, such as phenotypic plasticity. As there are different types of environmental variations, the optimal type of plasticity also differs. However, plasticity is not always adaptive but can sometimes result in phenotype further away from the optimum. In the thesis I investigate how different types of environmental variation influence adaptation and phenotypic plasticity. I used experimental evolution approaches (Paper I, II) and RNA interference, (Paper III) in Caenorhabditis remanei (Paper I, II) and Caenorhabditis elegans (Paper III). In Paper IV I tested whether trade-offs with lifespan are caused by energy allocation, and if there are trans-generational fitness effects. In Paper I I show that the evolution of life histories, indeed, depends on whether organisms evolve in stable, fluctuating or variable temperatures. I also show, that the plastic response to temperature is in line with the temperature-size rule and that this response is adaptive. In Paper II I look closer on the evolutionary response to highly variable environments. I show that worms respond to fast changes in temperature by increasing the degree of phenotypic plasticity, rather than using bet-hedging. I again confirmed that plasticity in size follows the temperature size rule and that it is adaptive. In Paper III I examine how organisms respond to temperature changes that occur within their lifetime. I found that after initial decrease in growth rate as a response to cold temperatures, once temperature increases worms exhibit increased growth rate, which corresponds to the compensatory growth plasticity. Interestingly, the worms didn’t pay any cost in longevity or reproduction but had higher fitness. In addition, I show that temperature-induced compensatory growth is regulated by TRPA-1 ion channel (trpa-1gene). Finally, in Paper IV, I show that optimization of gene expression by down-regulation of insulin/IGF-1 signaling via daf-2 RNAi from sexual maturity in C. elegans can more than double longevity without imposing any cost on reproduction. This is not expected if investment in lifespan and reproduction compete for the same energy pool. Importantly, I also showed that the positive effects for the parents did not come at a trans-generational cost for the offspring, since they exhibited increased reproduction and fitness.
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| 3. |
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| 4. |
- Sekajova, Zuzana, et al.
(författare)
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Evolution during uncorrelated environmental fluctuations : bet-hedging or phenotypic plasticity?
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Evolution in fluctuating environments is predicted to select for phenotypic plasticity or bet-hedging, depending on the accuracy of environmental cues and type of fluctuations. While these two alternatives are often contrasted in theoretical studies, their evolution are seldom studied together in empirical work.We used experimental evolution in the nematode worm Caenorhabditis remanei to simultaneously study the evolution of plasticity and bet-hedging in environments differing only in their temperature variability. We exposed worms for 30 generations to either fast fluctuating or slowly increasing temperature, these two environments had the same average temperature over evolutionary time. After experimental evolution, we scored size at sexual maturity and fitness in full siblings reared in two different temperatures, optimal 20°C and mildly stressful 25°C.Experimental evolution in the fluctuating environment resulted in the evolution of increased body size plasticity but not increased bet-hedging, compared to evolution in the slowly changing environment. Plasticity followed the temperature size rule as size decreased with increasing temperature and this plastic response was adaptive. In addition, we discovered substantial standing genetic variation in body size, which represents a potential for further evolutionary change.
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| 5. |
- Sekajova, Zuzana
(författare)
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Evolutionary significance of plastic responses within and across generations
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Until recently, all the resemblances between parents and their offspring were often ascribed to genes. Indeed, there is no doubt that DNA plays a central role in heredity. However, in recent years, it has become apparent that various non-genetic factors, independent of the DNA sequence, can also be passed from one generation to another, and in some cases even over as many as 80 generations. These effects include phenomena such as parental effects and epigenetic inheritance; two forms of trans-generational plasticity. In contrast to trans-generational plasticity, which allows for trait transmission across multiple generations, within-generational plasticity acts within one generation and includes phenomena such as environment-specific trait expression or catch-up growth. Plastic responses are especially advantageous in heterogeneous environment in which genetic mutations may not arise fast enough to allow organisms to cope with new conditions. In such cases, plastic responses may offer a better strategy and character of the environment will determine which form of plastic responses will be present. Both within-and trans-generational plasticity may alter the rate and direction of adaptation and can therefore have important implications for evolution. However, each type of plastic response is distinct and will thus alter adaptation in a unique way. Here I provide a detailed description of some of the most important forms of plastic responses and their consequences for adaptation.
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| 6. |
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| 7. |
- Sekajova, Zuzana, et al.
(författare)
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Temperature-induced compensatory growth in C. elegans is regulated by thermosensitive TRP channel and increases reproductive fitness
- 2022
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Ingår i: Functional Ecology. - : John Wiley & Sons. - 0269-8463 .- 1365-2435. ; 36:9, s. 2176-2187
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Tidskriftsartikel (refereegranskat)abstract
- Animals are often not growing at the maximum rate, but can compensate for a bad start of life by subsequently increasing growth rate. While this compensatory growth is widespread, its direct fitness consequences are seldom investigated and its genetic basis is unknown.We investigated the genetic regulation, as well as fitness and lifespan consequences of compensatory growth in response to temperature, using Caenorhabditis elegans knockout of the thermo-sensitive TRP ion channel TRPA-1, involved in temperature recognition. We exposed juvenile worms to cold, favourable (intermediate) or warm temperatures in order to delay or speed up development.Wild-type worms initially exposed to cold temperature experienced slower growth but after being switched to a more favourable temperature, they expressed compensatory growth and caught up in size. Those initially reared at warmer temperatures than favourable experienced slower growth and attained smaller adult size after being switched to the most favourable temperature.Compensatory growth also altered the reproductive schedule. While rate-sensitive individual fitness decreased by cold juvenile temperatures, as a direct effect of the substantial developmental delay, once worms returned to more favourable temperature, they shifted their reproductive schedule towards early reproduction. Therefore, when focusing on the post-treatment period, the reproductive rate increased even though lifetime reproductive success was unaffected. Surprisingly, compensatory growth did not reduce adult lifespan. In contrast to the findings for wild-type worms, juvenile temperature did not induce compensatory or slowed-down growth in the trpa-1 knockout mutants.We thus show that the trpa-1 is involved in the network regulating temperature-induced compensatory growth in C. elegans and that this compensatory growth can influence the reproductive rate.
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| 8. |
- Sekajova, Zuzana, et al.
(författare)
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Temperature-induced compensatory growth in the nematode Caenorhabditis elegans is regulated by a thermosensitive TRP channel and influences reproductive rate
- 2022
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 36:9, s. 2176-2187
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Tidskriftsartikel (refereegranskat)abstract
- Animals are often not growing at the maximum rate, but can compensate for a bad start of life by subsequently increasing growth rate. While this compensatory growth is widespread, its direct fitness consequences are seldom investigated and its genetic basis is unknown. We investigated the genetic regulation, as well as fitness and lifespan consequences of compensatory growth in response to temperature, using Caenorhabditis elegans knockout of the thermo-sensitive TRP ion channel TRPA-1, involved in temperature recognition. We exposed juvenile worms to cold, favourable (intermediate) or warm temperatures in order to delay or speed up development. Wild-type worms initially exposed to cold temperature experienced slower growth but after being switched to a more favourable temperature, they expressed compensatory growth and caught up in size. Those initially reared at warmer temperatures than favourable experienced slower growth and attained smaller adult size after being switched to the most favourable temperature. Compensatory growth also altered the reproductive schedule. While rate-sensitive individual fitness decreased by cold juvenile temperatures, as a direct effect of the substantial developmental delay, once worms returned to more favourable temperature, they shifted their reproductive schedule towards early reproduction. Therefore, when focusing on the post-treatment period, the reproductive rate increased even though lifetime reproductive success was unaffected. Surprisingly, compensatory growth did not reduce adult lifespan. In contrast to the findings for wild-type worms, juvenile temperature did not induce compensatory or slowed-down growth in the trpa-1 knockout mutants. We thus show that the trpa-1 is involved in the network regulating temperature-induced compensatory growth in C. elegans and that this compensatory growth can influence the reproductive rate. Read the free Plain Language Summary for this article on the Journal blog.
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| 9. |
- Sekajova, Zuzana, et al.
(författare)
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Within-family intergenerational trends in age at menarche relative to political changes in Czechoslovakia after World War II
- 2022
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Ingår i: American Journal of Human Biology. - : John Wiley & Sons. - 1042-0533 .- 1520-6300. ; 34:1
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of the study was to examine a secular trend in age at menarche (AAM) in the former Czechoslovak (and descendant Slovak and Czech) population in relation to its large-scale political and social events taking place after World War II.Methods: The study included 211 women aged 18-30 (born during 1984-1998), and their relatives: mothers, sisters, and grandmothers, yielding a total of 421 women. Changes in retrospectively recalled AAM between the three generations of women (oldest-grandmothers, middle-mothers, and youngest-daughters) were studied in pairwise comparisons. Relationships between AAM and the birth/conception date were analyzed relative to three events in the post-WWII Czechoslovakia (1948, 1968, and 1989).Results: AAM was the highest in the oldest generation, slightly lower in the middle generation and the lowest in the youngest generation. Mixed-Effect Model showed statistically significant interaction between the date of conception, historical events, and the period before and after the event.Conclusions: The recorded decline in AAM is congruent with secular trends reported in the literature. However, the decreasing trend was not linear and included an increase in AAM in women conceived within the five-year period after the invasion of Czechoslovakia by communist armies in 1968.
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| 10. |
- Zwoinska, Martyna K., et al.
(författare)
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Artificial selection for increased dispersal results in lower fitness
- 2020
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 33:2, s. 217-224
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Tidskriftsartikel (refereegranskat)abstract
- Dispersal often covaries with other traits, and this covariation was shown to have a genetic basis. Here, we wanted to explore to what extent genetic constraints and correlational selection can explain patterns of covariation between dispersal and key life-history traits-lifespan and reproduction. A prediction from the fitness-associated dispersal hypothesis was that lower genetic quality is associated with higher dispersal propensity as driven by the benefits of genetic mixing. We wanted to contrast it with a prediction from a different model that individuals putting more emphasis on current rather than future reproduction disperse more, as they are expected to be more risk-prone and exploratory. However, if dispersal has inherent costs, this will also result in a negative genetic correlation between higher rates of dispersal and some aspects of performance. To explore this issue, we used the dioecious nematode Caenorhabditis remanei and selected for increased and decreased dispersal propensity for 10 generations, followed by five generations of relaxed selection. Dispersal propensity responded to selection, and females from high-dispersal lines dispersed more than females from low-dispersal lines. Females selected for increased dispersal propensity produced fewer offspring and were more likely to die from matricide, which is associated with a low physiological condition in Caenorhabditis nematodes. There was no evidence for differences in age-specific reproductive effort between high- and low-dispersal females. Rather, reproductive output of high-dispersal females was consistently reduced. We argue that our data provide support for the fitness-associated dispersal hypothesis.
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