The Experts below are selected from a list of 2745 Experts worldwide ranked by ideXlab platform
Muhammad Asghar - One of the best experts on this subject based on the ideXlab platform.
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chronic infection hidden costs of infection chronic malaria accelerates telomere degradation and senescence in wild birds
Science, 2015Co-Authors: Muhammad Asghar, Dennis Hasselquist, Bengt Hansson, Pavel Zehtindjiev, Helena Westerdahl, Staffan BenschAbstract:Recovery from infection is not always complete, and mild chronic infection may persist. Although the direct costs of such infections are apparently small, the potential for any long-term effects on Darwinian Fitness is poorly understood. In a wild population of great reed warblers, we found that low-level chronic malaria infection reduced life span as well as the lifetime number and quality of offspring. These delayed Fitness effects of malaria appear to be mediated by telomere degradation, a result supported by controlled infection experiments on birds in captivity. The results of this study imply that chronic infection may be causing a series of small adverse effects that accumulate and eventually impair phenotypic quality and Darwinian Fitness.
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hidden costs of infection chronic malaria accelerates telomere degradation and senescence in wild birds
Science, 2015Co-Authors: Muhammad Asghar, Dennis Hasselquist, Bengt Hansson, Pavel Zehtindjiev, Helena Westerdahl, Staffan BenschAbstract:Recovery from infection is not always complete, and mild chronic infection may persist. Although the direct costs of such infections are apparently small, the potential for any long-term effects on Darwinian Fitness is poorly understood. In a wild population of great reed warblers, we found that low-level chronic malaria infection reduced life span as well as the lifetime number and quality of offspring. These delayed Fitness effects of malaria appear to be mediated by telomere degradation, a result supported by controlled infection experiments on birds in captivity. The results of this study imply that chronic infection may be causing a series of small adverse effects that accumulate and eventually impair phenotypic quality and Darwinian Fitness.
Staffan Bensch - One of the best experts on this subject based on the ideXlab platform.
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chronic infection hidden costs of infection chronic malaria accelerates telomere degradation and senescence in wild birds
Science, 2015Co-Authors: Muhammad Asghar, Dennis Hasselquist, Bengt Hansson, Pavel Zehtindjiev, Helena Westerdahl, Staffan BenschAbstract:Recovery from infection is not always complete, and mild chronic infection may persist. Although the direct costs of such infections are apparently small, the potential for any long-term effects on Darwinian Fitness is poorly understood. In a wild population of great reed warblers, we found that low-level chronic malaria infection reduced life span as well as the lifetime number and quality of offspring. These delayed Fitness effects of malaria appear to be mediated by telomere degradation, a result supported by controlled infection experiments on birds in captivity. The results of this study imply that chronic infection may be causing a series of small adverse effects that accumulate and eventually impair phenotypic quality and Darwinian Fitness.
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hidden costs of infection chronic malaria accelerates telomere degradation and senescence in wild birds
Science, 2015Co-Authors: Muhammad Asghar, Dennis Hasselquist, Bengt Hansson, Pavel Zehtindjiev, Helena Westerdahl, Staffan BenschAbstract:Recovery from infection is not always complete, and mild chronic infection may persist. Although the direct costs of such infections are apparently small, the potential for any long-term effects on Darwinian Fitness is poorly understood. In a wild population of great reed warblers, we found that low-level chronic malaria infection reduced life span as well as the lifetime number and quality of offspring. These delayed Fitness effects of malaria appear to be mediated by telomere degradation, a result supported by controlled infection experiments on birds in captivity. The results of this study imply that chronic infection may be causing a series of small adverse effects that accumulate and eventually impair phenotypic quality and Darwinian Fitness.
Jean Clobert - One of the best experts on this subject based on the ideXlab platform.
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reproductive allocation strategies a long term study on proximate factors and temporal adjustments in a viviparous lizard
Oecologia, 2013Co-Authors: Josefa Bleu, Jeanfrancois Le Galliard, Patrick S Fitze, Jean Clobert, Sandrine Meylan, Manuel MassotAbstract:Optimisation of reproductive investment is crucial for Darwinian Fitness, and detailed long-term studies are especially suited to unravel reproductive allocation strategies. Allocation strategies depend on the timing of resource acquisition, the timing of resource allocation, and trade-offs between different life-history traits. A distinction can be made between capital breeders that fuel reproduction with stored resources and income breeders that use recently acquired resources. In capital breeders, but not in income breeders, energy allocation may be decoupled from energy acquisition. Here, we tested the influence of extrinsic (weather conditions) and intrinsic (female characteristics) factors during energy storage, vitellogenesis and early gestation on reproductive investment, including litter mass, litter size, offspring mass and the litter size and offspring mass trade-off. We used data from a long-term study of the viviparous lizard, Lacerta (Zootoca) vivipara. In terms of extrinsic factors, rainfall during vitellogenesis was positively correlated with litter size and mass, but temperature did not affect reproductive investment. With respect to intrinsic factors, litter size and mass were positively correlated with current body size and postpartum body condition of the previous year, but negatively with parturition date of the previous year. Offspring mass was negatively correlated with litter size, and the strength of this trade-off decreased with the degree of individual variation in resource acquisition, which confirms theoretical predictions. The combined effects of past intrinsic factors and current weather conditions suggest that common lizards combine both recently acquired and stored resources to fuel reproduction. The effect of past energy store points out a trade-off between current and future reproduction.
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Physical performance and Darwinian Fitness in lizards
Nature, 2004Co-Authors: Jean François Le Galllard, Jean Clobert, Régis FerrièreAbstract:Strong evidence for a genetic basis of variation in physical performance has accumulated(1,2). Considering one of the basic tenets of evolutionary physiology-that physical performance and Darwinian Fitness are tightly linked(3)-one may expect phenotypes with exceptional physiological capacities to be promoted by natural selection. Why then does physical performance remain considerably variable in human and other animal populations(1,2,4)? Our analysis of locomotor performance in the common lizard (Lacerta vivipara) demonstrates that initial endurance (running time to exhaustion measured at birth) is indeed highly heritable, but natural selection in favour of this trait can be unexpectedly weak. A manipulation of dietary conditions unravels a proximate mechanism explaining this pattern. Fully fed individuals experience a marked reversal of performance within only one month after birth: juveniles with low endurance catch up, whereas individuals with high endurance lose their advantage. In contrast, dietary restriction allows highly endurant neonates to retain their locomotor superiority as they age. Thus, the expression of a genetic predisposition to high physical performance strongly depends on the environment experienced early in life.
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trade offs in phenotypic traits endurance at birth growth survival predation and susceptibility to parasitism in a lizard lacerta vivipara
Functional Ecology, 2000Co-Authors: Jean Clobert, Anne Oppliger, Gabriele Sorci, Bruno Ernande, John G Swallow, Theodore GarlandAbstract:1Considerable within-population variability of locomotor performance traits has been shown to exist in several species of squamate reptiles. In general, high values for speed and endurance are thought to have positive effects on the ability to capture prey, escape from predators, compete with conspecifics and acquire mates. On the other hand, variation in performance might trade-off with other components of Fitness such that the net effect on Darwinian Fitness is unpredictable. 2Gravid females of the common lizard (Lacerta vivipara) were captured and several phenotypic traits of their offspring measured immediately following birth. These were endurance, body length and body mass. Offspring were marked for individual identification, released into the field, and correlations between the phenotypic traits and their subsequent growth, activity and survival rate over the next months were then tested for. Parasitism by hematozoa was monitored and predation risk by tail losses estimated. 3It was found that individuals with a low endurance at birth tended to have reduced activity and growth rate, and higher parasite load; on the positive side, however, they experienced lower predation risk as assessed by tail losses. Conversely, individuals with a high endurance at birth had high activity and growth rates, low parasite load, but higher incidence of broken tails. Finally, endurance at birth was not correlated with survivorship up to the age of sexual maturity. Thus, individuals with varying locomotor endurance seem to exhibit behaviours that may result in the same level of Darwinian Fitness. 4The possibility that our results reveal a trade-off between the risk of becoming infected with parasites when lizards are less active (which is related to having lower endurance) vs the risk of being predated when the lizards are more active (higher endurance) is discussed.
Barry Sinervo - One of the best experts on this subject based on the ideXlab platform.
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Integration of Genotype, Physiological Performance, and Survival in a Lizard (Uta stansburiana) with Alternative Mating Strategies.
Physiological and biochemical zoology : PBZ, 2019Co-Authors: Lisa C. Hazard, Daniel P. Costa, Kenneth A. Nagy, Donald B. Miles, Erik I. Svensson, Barry SinervoAbstract:Covariation among behavioral and physiological traits is thought to enhance reproductive success and Darwinian Fitness. Species that exhibit alternative mating strategies provide excellent opportunities to assess the relative contributions of physiological and behavioral traits to Fitness. Male side-blotched lizards (Uta stansburiana) exhibit three heritable throat color morphs that are associated with alternative mating behaviors. The three morphs differ in resource holding potential, mate attraction, mate defense, and physiological performance. We examined interrelationships of body mass, stamina, field metabolic rate, growth rate, and survival to the second capture (a Fitness proxy). Relationships among variables were complex, and mass, stamina, and throat color interacted to predict male survival. Our analyses suggest that male side-blotched lizards exhibit trade-offs among physiological traits related to reproductive success and survival and that differential survival for different combinations of traits has caused correlational selection, leading to adaptive integration of phenotypic traits associated with alternative mating strategies.
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testosterone endurance and Darwinian Fitness natural and sexual selection on the physiological bases of alternative male behaviors in side blotched lizards
Hormones and Behavior, 2000Co-Authors: Donald B. Miles, Barry Sinervo, Anthony W Frankino, Matthew Klukowski, Dale F DenardoAbstract:The mechanistic bases of natural and sexual selection on physiological and behavioral traits were examined in male morphs of three colors of the side-blotched lizard, Uta stansburiana. Orange-throated males are aggressive and defend large territories with many females. Blue-throated males defend smaller territories with fewer females; however, blue-throated males assiduously mate guard females on their territory. Yellow-throated males do not defend a territory, but patrol a large home range. They obtain secretive copulations from females on the territories of dominant males. Males with bright orange throats had higher levels of plasma testosterone (T), endurance, activity, and home range size and concomitantly gained greater control over female home ranges than blue- or yellow-throated males. Experimentally elevating plasma T in yellow- and blue-throated males increased their endurance, activity, home range size, and control over female territories to levels that were seen in unmanipulated orange-throated males that had naturally high plasma T. However, the enhanced performance of orange-throated males is not without costs. Orange-throated males had low survival compared to the other morphs. Finally, some yellow-throated males transformed to a partial blue morphology late in the season and the endurance of these transforming yellow-throated males increased from early to late in the season. In addition, yellow-throated males that transformed to blue also had significantly higher plasma T late in the season compared to the plasma T earlier in the season. T appears to play an important role in the physiological changes that all three color morphs undergo during the process of maturation. In some yellow males, T plays an additional role in plastic changes in behavior and physiology late in the reproductive season. We discuss natural and sexual selection on physiological and behavioral traits that leads to the evolution of steroid regulation in the context of alternative male strategies.
Adam K Chippindale - One of the best experts on this subject based on the ideXlab platform.
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intralocus sexual conflict diminishes the benefits of sexual selection
PLOS Biology, 2006Co-Authors: Alison Pischedda, Adam K ChippindaleAbstract:Evolution based on the benefits of acquiring “good genes” in sexual selection is only plausible with the reliable transmission of genetic quality from one generation to the next. Accumulating evidence suggests that sexually antagonistic (SA) genes with opposite effects on Darwinian Fitness when expressed in the two different sexes may be common in animals and plants. These SA genes should weaken the potential indirect genetic benefits of sexual selection by reducing the Fitness of opposite-sex progeny from high-Fitness parents. Here we use hemiclonal analysis in the fruit fly, Drosophila melanogaster, to directly measure the inheritance of Fitness across generations, over the entire genome. We show that any potential genetic benefits of sexual selection in this system are not merely weakened, but completely reversed over one generation because high-Fitness males produce low-Fitness daughters and high-Fitness mothers produce low-Fitness sons. Moreover, male Fitness was not inherited by sons, consistent with both theory and recent evidence connecting this form of SA variation with the X chromosome. This inheritance pattern may help to explain how genetic variation for Fitness is sustained despite strong sexual selection, and why the ZW sex chromosome system found in birds and butterflies appears to foster the evolution of extreme secondary sexual characters in males.
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negative genetic correlation for adult Fitness between sexes reveals ontogenetic conflict in drosophila
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Adam K Chippindale, Jonathan R Gibson, William R RiceAbstract:Because of their distinctive roles in reproduction, females and males are selected toward different optimal phenotypes. Ontogenetic conflict between the sexes arises when homologous traits are selected in different directions. The evolution of sexual dimorphism by sex-limited gene expression alleviates this problem. However, because the majority of genes are not sex-limited, the potential for substantial conflict may remain. Here we assess the degree of ontogenetic conflict in the fruit-fly, Drosophila melanogaster, by cloning 40 haploid genomes and measuring their Darwinian Fitness in both sexes. The intersexual genetic correlations for juvenile viability, adult reproductive success, and total Fitness were used to gauge potential conflict during development. First, as juveniles, where the Fitness objectives of the two sexes appear to be similar, survival was strongly positively correlated across sexes. Second, after adult maturation, where gender roles diverge, a significant negative correlation for reproductive success was found. Finally, because of counterbalancing correlations in the juvenile and adult components, no intersexual correlation for total Fitness was found. Highly significant genotype-by-gender interaction variance was measured for both adult and total Fitness. These results demonstrate strong intersexual discord during development because of the expression of sexually antagonistic variation.
