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| 2. |
- Reinke, Beth A, et al.
(författare)
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Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 376:6600, s. 1459-1466
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Tidskriftsartikel (refereegranskat)abstract
- Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.
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| 3. |
- Friesen, C. R., et al.
(författare)
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Covariation in superoxide, sperm telomere length and sperm velocity in a polymorphic reptile
- 2020
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 74:6
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Tidskriftsartikel (refereegranskat)abstract
- Telomeres are DNA-protein caps at the ends of chromosomes that have been shown to be associated with male fertility may be heritable, reflect environmental influences and predict life span in some taxa. If heritable, paternal telomere length would be transmitted via sperm in the form of sperm telomere length (STL). We, therefore, investigated STL, sperm number and velocity in the Australian-painted dragon lizard, Ctenophorus pictus, an agamid lizard with distinct male colour morphs and related reproductive tactics. We measured telomere length in the sperm and blood as well as superoxide levels, as a measure for the potential for oxidative stress and ejaculate quality. We also noted a male's head colour (red, orange, yellow or blue) and whether or not they had a yellow gular bib. Previous research has reported that yellow males outcompete red males in sperm competition; we found that yellow males had significantly shorter STL than red males. Males with bibs had greater STL than did males without bibs. Superoxide levels measured in the blood were negatively correlated with STL. Whole blood TL and body length were weakly but positively correlated with STL. Superoxide measurements were negatively correlated with progressive sperm motility and straight line sperm velocity across all males. The ejaculates of males with bibs had lower sperm counts and velocity than males without bibs. Our research adds to the growing research that indicates the importance of considering both somatic and gametic telomeres when assessing the interaction between telomere dynamics, life history and reproductive strategies. Significance statement Telomeres are DNA-protein caps at the ends of chromosomes that reflect environmental stress may be heritable and epigenetically modified, may predict life span in some taxa and may influence the probability of paternity in sperm competition. Ours is one of the first studies to examine correlates of sperm telomere length in a non-mammalian, polymorphic species, but much more remains to be done. Telomere research in non-model species has focused on survival consequences of variation in telomere traits with less attention paid to the fact that sperm (and egg) telomere biology can link life history traits directly to reproductive physiology. We chose to investigate sperm velocity and sperm telomere length (STL) in the painted dragon lizard, Ctenophorus pictus, an agamid lizard with distinct male morphs and associated reproductive tactics. We also observed morph-specific differences in ejaculate quality and STL; in particular, males with yellow bibs had longer STL but poorer ejaculate quality metrics (e.g., number of sperm, velocity and proportion of progressively motile sperm) than males without the throat patch. The differences in STL between the morphs and the negative relationship between sperm velocity and STL, along with previous work on this species, suggest that telomere length and dynamics may be linked with the reproductive tactics of colour morphs within this species.
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| 4. |
- Gau, Rémi, et al.
(författare)
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Brainhack : Developing a culture of open, inclusive, community-driven neuroscience
- 2021
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Ingår i: Neuron. - : Elsevier. - 0896-6273 .- 1097-4199. ; 109:11, s. 1769-1775
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Tidskriftsartikel (refereegranskat)abstract
- Brainhack is an innovative meeting format that promotes scientific collaboration and education in an open, inclusive environment. This NeuroView describes the myriad benefits for participants and the research community and how Brainhacks complement conventional formats to augment scientific progress.
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| 5. |
- Rollings, N., et al.
(författare)
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Sex- And tissue-specific differences in telomere length in a reptile
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:11, s. 6211-6219
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Tidskriftsartikel (refereegranskat)abstract
- The usage of telomere length (TL) in blood as a proxy for the TL of other tissues relies on the assumption that telomere dynamics across all tissues are similar. However, telomere attrition can be caused by reactive oxygen species (ROS) which may vary with metabolic rate, which itself varies across organs depending upon the life history strategy of an organism. Thus, we chose to measure the telomeres of various cell types in juvenile painted dragon lizards, Ctenophorus pictus, given their unusual life history strategy. Individuals typically only experience a single mating season. We measured the TL of male and female dragons using qPCR and observed that TL varied with tissue type and sex. Telomeres of blood cells were longer than those of liver, heart, brain, and spleen, and females had longer telomeres than males. Brain telomeres in males were approximately half the length of those in females. Telomeric attrition in the male brain may be due to the need for rapid learning of reproductive tactics (territory patrol and defense, mate-finding). Significant correlations between the TL of tissue types suggest that blood TL may be a useful proxy for the TL of other tissues. Our comparison of organ-specific telomere dynamics, the first in a reptile, suggests that the usage of blood TL as a proxy requires careful consideration of the life history strategy of the organism. © 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
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- Shine, R., et al.
(författare)
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Why do males have longer tails than females?
- 1999
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - 0962-8452 .- 1471-2954. ; 266, s. 2147-2151
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Tidskriftsartikel (refereegranskat)
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| 13. |
- Thompson, WH, et al.
(författare)
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A data resource from concurrent intracranial stimulation and functional MRI of the human brain
- 2020
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Ingår i: Scientific data. - : Springer Science and Business Media LLC. - 2052-4463. ; 7:1, s. 258-
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Tidskriftsartikel (refereegranskat)abstract
- Mapping the causal effects of one brain region on another is a challenging problem in neuroscience that we approached through invasive direct manipulation of brain function together with concurrent whole-brain measurement of the effects produced. Here we establish a unique resource and present data from 26 human patients who underwent electrical stimulation during functional magnetic resonance imaging (es-fMRI). The patients had medically refractory epilepsy requiring surgically implanted intracranial electrodes in cortical and subcortical locations. One or multiple contacts on these electrodes were stimulated while simultaneously recording BOLD-fMRI activity in a block design. Multiple runs exist for patients with different stimulation sites. We describe the resource, data collection process, preprocessing using the fMRIPrep analysis pipeline and management of artifacts, and provide end-user analyses to visualize distal brain activation produced by site-specific electrical stimulation. The data are organized according to the brain imaging data structure (BIDS) specification, and are available for analysis or future dataset contributions on openneuro.org including both raw and preprocessed data.
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| 21. |
- Lurie, DJ, et al.
(författare)
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Questions and controversies in the study of time-varying functional connectivity in resting fMRI
- 2020
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Ingår i: Network neuroscience (Cambridge, Mass.). - : MIT Press - Journals. - 2472-1751. ; 4:1, s. 30-69
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Tidskriftsartikel (refereegranskat)abstract
- The brain is a complex, multiscale dynamical system composed of many interacting regions. Knowledge of the spatiotemporal organization of these interactions is critical for establishing a solid understanding of the brain’s functional architecture and the relationship between neural dynamics and cognition in health and disease. The possibility of studying these dynamics through careful analysis of neuroimaging data has catalyzed substantial interest in methods that estimate time-resolved fluctuations in functional connectivity (often referred to as “dynamic” or time-varying functional connectivity; TVFC). At the same time, debates have emerged regarding the application of TVFC analyses to resting fMRI data, and about the statistical validity, physiological origins, and cognitive and behavioral relevance of resting TVFC. These and other unresolved issues complicate interpretation of resting TVFC findings and limit the insights that can be gained from this promising new research area. This article brings together scientists with a variety of perspectives on resting TVFC to review the current literature in light of these issues. We introduce core concepts, define key terms, summarize controversies and open questions, and present a forward-looking perspective on how resting TVFC analyses can be rigorously and productively applied to investigate a wide range of questions in cognitive and systems neuroscience.
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| 22. |
- Löwenborg, Kristin, et al.
(författare)
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Fitness disadvantages to disrupted embryogenesis impose selection against suboptimal nest-site choice by female grass snakes, Natrix natrix (Colubridae)
- 2011
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 24:1, s. 177-183
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypic traits of hatchling reptiles are strongly influenced by incubation regimes (e.g. of temperature and moisture), suggesting that maternal choice of suitable nest-sites should be under intense selection. Our laboratory incubation of 209 eggs (17 clutches) from wild-caught Swedish grass snakes (Natrix natrix) showed that scale abnormalities (half-scales on one side of the body, often reflecting lateral asymmetry in the number of ribs) occurred more frequently if eggs were incubated under cooler conditions. Especially at low incubation temperatures, individuals with scale asymmetries took longer to hatch than did symmetric conspecifics, were smaller in body length at hatching and were slower in trials of locomotor speed. Anti-predator tactics also covaried with scale asymmetry. These patterns suggest that individuals with asymmetric scales should have lower fitness and hence should rarely survive to adulthood in the wild. We tested this prediction by examining 201 field-collected snakes from museum collections. As predicted, scale asymmetries were seen primarily in small snakes, and rarely in larger animals. We interpret these data to suggest that scale asymmetries in this species offer an index of developmental instability and that fitness disadvantages to disrupted embryogenesis impose selection against suboptimal nest-site choice by females.
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| 24. |
- Madsen, Thomas, et al.
(författare)
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Paternal alleles enhance female reproductive success in tropical pythons
- 2005
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Ingår i: Molecular Ecology. - 0962-1083. ; 14:6, s. 1783-1787
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Tidskriftsartikel (refereegranskat)abstract
- The conventional view that female reproductive success is unlikely to benefit from multiple mating has come under strong challenge in recent years. In the present study, we demonstrate that the time wild-caught reproductive female water pythons (Liasis fuscus) spent in the laboratory prior to oviposition affected both hatching success and the number of male microsatellite alleles detected in the broods. A negative correlation between time in captivity and number of male alleles observed in the broods suggests that reduced hatching success was most likely not caused by environmental factors such as nonoptimal temperatures, but rather by restricted mating opportunities. Maternal nutritional status and mean hatchling mass did not affect brood viability. However, our results revealed a positive correlation between number of male microsatellite alleles observed in the broods and hatching success, suggesting that increased paternal genetic variability enhanced female reproductive success. As microsatellite loci are unlikely to be direct targets of selection, we suggest that variability at these loci may cosegregate with other polymorphic genes directly linked to fitness.
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| 26. |
- Madsen, Thomas, et al.
(författare)
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Population size and genetic diversity in sand lizards (Lacerta agilis) and adders (Vipera berus)
- 2000
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Ingår i: Biological Conservation. - 1873-2917. ; 94:2, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- Because low genetic diversity may threaten the viability of isolated populations, conservation biologists have devoted much effort to quantify genetic variation. Two techniques routinely used involve levels of mini- and microsatellite polymorphism, with the assumption that levels of variation at these parts of the genome will be reflected in levels of variation at other loci. Our data challenge this assumption. We studied six populations of sand lizards (Lacerta agilis) and five populations of adders (Vipera berus), differing considerably in size and degree of isolation. They, therefore, offer an opportunity to examine how population parameters affect genetic variation at different parts of the genome. Relative population size (based on degree of isolation and number of animals) was not correlated with either minisatellite variability or microsatellite heterozygosity. However, our measures of genetic diversity at the Mhc class I loci of both sand lizards and adders revealed a significant correlation between relative population size and Mhc polymorphism: non-isolated/larger populations exhibited higher genetic diversity than did isolated/small populations. Consequently, only the Mhc-based estimates of genetic diversity yielded results in agreement with population genetic theory. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 27. |
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| 28. |
- Madsen, Thomas, et al.
(författare)
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Rain, rats and pythons: Climate-driven population dynamics of predators and prey in tropical Australia
- 2006
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Ingår i: Austral Ecology. - : Wiley. - 1442-9985 .- 1442-9993. ; 31:1, s. 30-37
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- All natural populations fluctuate in abundance and age structure through time; understanding why they do so is a critical step towards their effective management and conservation. However, the long-term data sets needed for such an understanding are rarely available, especially for tropical organisms. A 17-year capture-mark–recapture study yielded detailed information on the demography of water pythons (Liasis fuscus) and their main prey, the dusky rat (Rattus colletti), on the Adelaide River flood plain in tropical Australia. The link between annual rainfall patterns and rat demography was highly non-linear. Rat numbers were low during years with low and high rainfall at the end of the wet season (April). Numbers of both predators and prey fluctuated considerably among years. Annual fluctuations in rat numbers generated a corresponding variation in rates of female python reproduction, python body condition and survival. Although variation in recruitment, survival and prey abundance all had a significant impact on annual fluctuations in python numbers, our analyses suggest that recruitment constituted the main determinant in driving the population dynamics of these large tropical predators. In combination with our other studies on this system, the data show that population dynamics of the water python population is ultimately driven by annual variation in rainfall, mediated via shifts in prey availability. The water pythons and the dusky rats of the Adelaide River flood plain thus demonstrate an unusually clear and direct link between an abiotic factor (rainfall) and predator–prey population dynamics.
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| 29. |
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| 30. |
- Madsen, Thomas, et al.
(författare)
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Size matters: extraordinary rodent abundance on an Australian tropical flood plain
- 2006
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Ingår i: Austral Ecology. - : Wiley. - 1442-9985 .- 1442-9993. ; 31:3, s. 361-365
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Tidskriftsartikel (refereegranskat)abstract
- Published estimates of the total biomass of natural populations of mammalian herbivores generally have ignored small-bodied taxa (especially, rodents). Including such taxa may dramatically change our understanding of total biomass and energy flow in such systems. Dusky rats (Rattus colletti) are small (up to 210 g) native Australian mammals, and our 5-year mark-recapture study on a tropical flood plain (Adelaide River, Northern Territory) revealed that rat biomass can reach extraordinary levels (up to 4.7 t km(-2)). Because their small body size results in high mass-specific metabolic rates, a given biomass of rodents has a several-fold higher total energy requirement than the same mass of large-bodied herbivores. Accordingly, during some years dusky rat biomass can be double that estimated for large herbivores on the world's most productive savannas in eastern and southern Africa. The huge rodent biomass strongly suggests that the Adelaide River flood plain must be an incredibly productive habitat. Considering the immense biological importance of these productive ecosystems, flood plain conservation must be placed high on the priority list of habitats that require immediate protection.
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| 37. |
- Olsson, M, et al.
(författare)
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Does mate guarding prevent rival mating in snow skinks? A test using AFLP
- 2005
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Ingår i: Herpetologica. - 0018-0831. ; 61:4, s. 389-394
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Tidskriftsartikel (refereegranskat)abstract
- We report on likely mixed paternity in a natural population of snow skinks (Niveoscincus mirolepidoms) from alpine Tasmania, Australia. This species is nonterritorial and males guard females after copulation, Suggesting that guarding behavior has evolved to prevent rival mating of still-receptive females. To what degree does this mate-guarding prevent rival copulations? We sampled gravid females at random in the wild and looked for within-clutch mixed paternity among their offspring using amplified fragment length polymorphism (AFLP). Incorpating all visualized fragments, offspring band-sharing based on maternal bands was 0.94 (+/- 0.05, SD), whereas for paternal fragments it was 0.54 (+/- 0.46, SD). We then tested paternal band-sharing scores for all young of pairs against the mean score of the maternally inherited fragments to assess whether paternal genetic variation was larger than for a known single parent, hence, suggesting multiple sires. To reduce the risk of unequal sampling of polymorphic maternal and paternal fragments, We based Our statistical tests on heterozygous bands only. Offspring band sharing based on maternal heterozygous fragments was on average 0.68 ( +/- 0.22, SD), versus 0.35 (+/- 0.33, SD) based on paternally inherited fragments. in six of eight clutches (75%), at least one pair of voting in a clutch had paternal scores outside of the confidence interval for a single parent (i.e., the mother). Thus, mixed paternity seems to be widespread in this Population, despite prolonged postcopulatory mate-guarding by males.
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| 41. |
- Olsson, Mats, 1960, et al.
(författare)
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Growth to death in lizards.
- 2003
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Ingår i: Evolution. - 0014-3820. ; 56:9, s. 1867-1870
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Tidskriftsartikel (refereegranskat)
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| 42. |
- Olsson, Mats, 1960, et al.
(författare)
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How accurately do behavioural observations predict reproductive success in free-ranging lizards?
- 2019
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- Behavioural ecologists often use data on patterns of male-female association to infer reproductive success of free-ranging animals. For example, a male seen with several females during the mating season is predicted to father more offspring than a male not seen with any females. We explored the putative correlation between this behaviour and actual paternity (as revealed by microsatellite data) from a long-term study on sand lizards (Lacerta agilis), including behavioural observations of 574 adult males and 289 adult females, and paternity assignment of more than 2500 offspring during 1998-2007. The number of males that contributed paternity to a female's clutch was correlated with the number of males seen accompanying her in the field, but not with the number of copulation scars on her body. The number of females that a male accompanied in the field predicted the number of females with whom he fathered offspring, and his annual reproductive success (number of progeny). Although behavioural data explained less than one-third of total variance in reproductive success, our analysis supports the utility of behavioural-ecology studies for predicting paternity in free-ranging reptiles.
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