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3,139 results for “fits”
The evolutionary advantage of fitness-dependent recombination in diploids: a deterministic mutation–selection–balance model
<p>Recombination's omnipresence in nature is one of the most intriguing problems in evolutionary biology. The question of why recombination exhibits certain general features is no less interesting than that of why it exists at all. One such feature is recombination's fitness dependence (FD). The so far developed population-genetics models have focused on the evolution of FD recombination mainly in haploids, although the empirical evidence for this phenomenon comes mostly from diploids. Using numerical analysis of modifier models for infinite panmictic populations, we show here that FD recombination can be evolutionarily advantageous in diploids subjected to purifying selection. We ascribe this advantage to the differential rate of disruption of lower- vs higher-fitness genotypes, which can be manifested in selected systems with at least three loci. We also show that if the modifier is linked to such selected system, it can additionally benefit from modifying this linkage in a fitness-dependent manner. The revealed evolutionary advantage of FD recombination appeared robust to crossover interference within the selected system, either positive or negative. Remarkably, FD recombination was often favored in situations where any constant non-zero recombination was evolutionarily disfavored, implying a relaxation of the rather strict constraints on major parameters (e.g., selection intensity and epistasis) required for the evolutionary advantage of non-zero recombination formulated by classical models.</p>
Sequential organization of birdsong: Relationships with individual quality and fitness
<p>Many vocalizing animals produce the discrete elements of their acoustic signals in a specific sequential order, but we know little about the biological relevance of this ordering. For that, we must characterize the degree by which individuals differ in how they organize their signals sequentially and relate these differences to variation in quality and fitness. In this study, we fulfilled these tasks in male collared flycatchers (<em>Ficedula albicollis</em>). We characterized the sequential order of syllables with a network analysis approach and studied the consistency of network variables on distinct time-scales (within-day, between-day, and between-year), and assessed their relationship with such quality indicators as age, body condition, arrival date, and fitness-related proxies like survival to the next year and pairing success. We found that the syllables were associated non-randomly with one another and both the frequency differences of consecutive syllables and the number of motif types were higher in the original than in randomized syllable sequences. Average degree and small-worldness showed considerable among-individual differences and decreasing repeatability with increasing time-scale. Furthermore, we found relationships between male age and average degree among and within individuals. Accordingly, older males produce syllable sequences by using common syllables less often than younger individuals. However, the network variables showed no relationship with fitness-related variables. In conclusion, the sequential organization of birdsong has the potential to encode individual-specific characteristics, which thus could be used as signals in social interactions and thus potentially could be subject to sexual selection.</p>
Heterozygosity–fitness correlations reveal inbreeding depression in neonatal body size in a critically endangered rock iguana
Inbreeding depression, though challenging to identify in nature, may play an important role in regulating the dynamics of small and isolated populations. Conversely, greater expression of genetic load can enhance opportunities for natural selection. Conditional expression concentrates these opportunities for selection and may lead to failure of detection. This study investigates the possibility for age-dependent expression of inbreeding depression in a critically endangered population of rock iguanas, Cyclura nubila caymanensis. We employ heterozygote-fitness correlations to examine the contributions of individual genetic factors to body size, a fitness-related trait. Nonsignificant reductions in homozygosity (up to 7%) were detected between neonates and individuals surviving past their first year, which may reflect natural absorption of inbreeding effects by this small, fecund population. The majority of variation in neonate body size was attributed to maternal or environmental effects (i.e., clutch identity and incubation length); however, heterozygosity across 22 microsatellite loci also contributed significantly and positively to model predictions. Conversely, effects of heterozygosity on fitness were not detectable when adults were examined, suggesting that inbreeding depression in body size may be age dependent in this taxon. Overall, these findings emphasize the importance of taking holistic, cross-generational approaches to genetic monitoring of endangered populations.
Data from: Facilitated exploitation of pollination mutualisms: fitness consequences for plants
Mutualisms are only rarely one-to-one interactions: each species generally interacts with multiple mutualists. Exploitation is ubiquitous in mutualisms, and we would therefore expect that each mutualist interacts with multiple exploiters as well. Exploiter species may also interact with one another. For example, the action of one exploiter species might open the opportunity for exploitation by a second species. Exploitation is common in many plant–pollinator mutualisms: 'primary' nectar robbers feed through holes they make in flowers, which can be subsequently used by 'secondary' nectar robbers unable to create holes themselves. The overall effect of nectar robbing on plant fitness is often (although not always) negative. No study has separated the effects of interacting with primary vs. secondary robbers. Here, we examine the effects of primary vs. secondary nectar robbing on pollinator visitation rate and female fitness in Ipomopsis aggregata. Manipulating the type of nectar robbing that flowers experienced, we found that secondary nectar robbing inflicted fitness costs to plants beyond that inflicted by primary robbing alone. Secondary nectar robbing significantly reduced pollen receipt to flowers, as well as fruit and seed production. Although the causes are elusive, the effect may be attributed to changes in pollinator behaviour at these plants. Synthesis. Our findings provide evidence that interacting with multiple exploiters can lead to increased negative effects for mutualists, and highlight the importance of incorporating multiple exploiters into the conceptual framework of mutualism.
Data from: Chronic anthropogenic noise disrupts glucocorticoid signaling and has multiple effects on fitness in an avian community
Anthropogenic noise is a pervasive pollutant that decreases environmental quality by disrupting a suite of behaviors vital to perception and communication. However, even within populations of noise-sensitive species, individuals still select breeding sites located within areas exposed to high noise levels, with largely unknown physiological and fitness consequences. We use a study system in the natural gas fields of northern New Mexico to test the prediction that exposure to noise causes glucocorticoid-signaling dysfunction and decreases fitness in a community of secondary cavity nesting birds. In accordance with these predictions, and across all species, we find strong support for noise exposure decreasing baseline corticosterone in adults and nestlings and, conversely, increasing acute stressor-induced corticosterone in nestlings. We also document fitness consequences with increased noise in the form of reduced hatching success in the western bluebird (Sialia mexicana), the species most likely to nest in noisiest environments. Nestlings of all three species exhibited accelerated growth of both feathers and body size at intermediate noise amplitudes compared to low or higher amplitudes. Our results are consistent with recent experimental laboratory studies, and show that noise functions as a chronic, inescapable stressor. Anthropogenic noise likely impairs environmental risk perception by species relying on acoustic cues, and, ultimately, leads to impacts on fitness. Our work, when taken together with recent efforts to document noise across the landscape, implies potential widespread, noise-induced chronic stress coupled with reduced fitness for many species reliant on acoustic cues.
Juvenile rank acquisition is associated with fitness independent of adult rank
<p>Social rank has been identified as a significant determinant of fitness in a variety of species. The importance of social rank suggests that the process by which juveniles come to establish their position in the social hierarchy is a critical component of development. Here, we use the highly predictable process of rank acquisition in spotted hyenas to study the consequences of variation in rank acquisition in early life. In spotted hyenas, rank is 'inherited' through a learning process called 'maternal rank inheritance.' This pattern is highly predictable: ~80% of juveniles acquire the exact rank predicted by the rules of maternal rank inheritance. This predictable nature of rank acquisition in these societies allows the process of rank acquisition to be studied independently from the ultimate rank that each juvenile attains. In this study, we use Elo-deviance scores, a novel application of the Elo-rating method, to calculate each juvenile's deviation from expected pattern of maternal rank inheritance during development. Despite variability in rank acquisition among juveniles, most of these juveniles come to attain the exact rank expected of them according to the rules of maternal rank inheritance. Nevertheless, we find that transient variation in rank acquisition in early life is associated with long term fitness consequences for these individuals: juveniles 'underperforming' their expected ranks show reduced survival and lower lifetime reproductive success than better-performing peers, and this relationship is independent of both maternal rank and rank achieved in adulthood. We also find that multiple sources of early life adversity have cumulative, but not compounding, effects on fitness. Future work is needed to determine variation in rank acquisition directly affects fitness, or if some other variable, such as maternal investment or juvenile condition, causes variation in both of these outcomes.</p>
Data from: Carotenoid pigmentation in salmon: Variation in expression at BCO2-l locus controls a key fitness trait affecting red colouration
Carotenoids are primarily responsible for the characteristic red flesh colouration of salmon. Flesh colouration is an economically and evolutionarily significant trait that varies inter- and intra-specifically, yet the underlying genetic mechanism is unknown. Chinook salmon (Oncorhynchus tshawytscha) represent an ideal system to study carotenoid variation as, unlike other salmonids, they exhibit extreme differences in carotenoid utilization due to genetic polymorphisms. Here, we crossed populations of Chinook salmon with fixed differences in flesh colouration (red vs. white) for a genome-wide association study (GWAS) to identify loci associated with pigmentation. Here, the beta-carotene oxygenase 2-like (BCO2-l) gene was significantly associated with flesh colour, with the most significant SNP explaining 66% of the variation in colour. BCO2 gene disruption is linked to carotenoid accumulation in other taxa, therefore we hypothesize that an ancestral mutation partially disrupting BCO2-l activity (i.e., hypomorphic mutation) allowed the deposition and accumulation of carotenoids within Salmonidae. Indeed, we found elevated transcript levels of BCO2-l in white Chinook salmon relative to red. The long-standing mystery of why salmon are red, while no other fishes are, is thus likely explained by a hypomorphic mutation in the proto-salmonid at the time of divergence of red-fleshed salmonid genera (~30 MYA).
Data from: Age-related variation in non-breeding foraging behaviour and carry-over effects on fitness in an extremely long-lived bird
1. Senescence has been widely documented in wild vertebrate populations, yet the proximate drivers of age-related declines in breeding success, including allocation trade-offs and links with foraging performance, are poorly understood. For long-lived, migratory species, the non-breeding period represents a critical time for investment in self-maintenance and restoration of body condition, which in many species is linked to fitness. However, the relationships between age, non-breeding foraging behaviour and fitness remain largely unexplored. 2. We performed a cross-sectional study, investigating age-related variation in the foraging activity, distribution and diet of an extremely long-lived seabird, the wandering albatross Diomedea exulans during the non-breeding period, and its links with subsequent reproductive performance. 3. We tracked the distributions of 82 adults aged 8 – 33 years with geolocator-immersion loggers and found an age-related decline in the number of landings (a proxy of foraging effort) during daylight hours. There was a decrease in body feather δ13C values in older males but not females, yet this did not accompany an age-related shift in distributions. Males conducted fewer landings than females, and the sexes were spatially segregated, with males foraging further south, likely due to their differential utilization of winds. 4. While younger (< 20 years) birds had higher foraging activity, all individuals went on to breed successfully the following season. In contrast, among older (20+ years) birds, individuals that landed more often were more likely to defer breeding or fail during incubation, suggesting they have lower foraging success. 5. As far as we are aware, this is the first demonstration of an age-specific carry-over effect of foraging behaviour in the non-breeding period on subsequent reproductive performance. This link between foraging behaviour and fitness in late but not early adulthood indicates that the ability of individuals to forage efficiently outside the breeding period may be an important driver of fitness differences in old age.
Diet composition and social environment determine food consumption, phenotype and fitness in an omnivorous insect
Nutrition is the single most important factor for individual's growth and reproduction. Consequently, the inability to reach the nutritional optimum imposes severe consequences for animal fitness. Yet, under natural conditions organisms may face a mixture of stressors that can modulate the effects of nutritional asymmetry. For instance, stressful environments caused by intense interaction with conspecifics. Here, we subjected the house-cricket Acheta domesticus to i) either of two types of diet that have proven to affect cricket performance and ii) simultaneously manipulated their social environment throughout their complete lifecycle. We aimed to track sex-specific consequences for multiple traits during insect development throughout all life stages. Both factors affected critical life-history traits with potential population-level consequences: Diet composition induced strong effects on insect development time, lifespan and fitness, whilst the social environment affected the number of nymphs that completed development, food consumption and whole-body lipid content. Additionally, both factors interactively determined female body mass. Our results highlight that insects may acquire and invest resources in a different manner when subjected to an intense interaction with conspecifics or when isolated. Furthermore, while only diet composition affected individual reproductive output, the social environment would determine the number of reproductive females, thus indirectly influencing population performance.
Data From: An artificial habitat increases the reproductive fitness of a range-shifting species within a newly colonized ecosystem
<p>When a range-shifting species colonizes an ecosystem it has not previously inhabited, it may experience suboptimal conditions that challenge its continued persistence and expansion. Some impacts may be partially mitigated by artificial habitat analogues: artificial habitats that more closely resemble a species' historic ecosystem than the surrounding habitat. If conditions provided by such habitats increase reproductive success, they could be vital to the expansion and persistence of range-shifting species. We investigated the reproduction of the mangrove tree crab <i>Aratus pisonii </i>in its historic mangrove habitat, the suboptimal colonized salt marsh ecosystem, and on docks within the marsh, an artificial mangrove analogue. Crabs were assessed for offspring production and quality, as well as measures of maternal investment and egg quality. <i>Aratus pisonii</i> found on docks produced more eggs, more eggs per unit energy investment, and higher quality larvae than conspecifics in the surrounding salt marsh. Yet, crabs in the mangrove produced the highest quality larvae. Egg lipids suggest these different reproductive outcomes result from disparities in the quality of diet-driven maternal investments, particularly key fatty acids. This study suggests habitat analogues may increase the reproductive fitness of range-shifting species allowing more rapid expansion into, and better persistence in, colonized ecosystems.</p>
Long-term research and hierarchical models reveal consistent fitness costs of being the last egg in a clutch
1. Maintenance of phenotypic heterogeneity in the face of strong selection is an important component of evolutionary ecology, as are the consequences of such heterogeneity. Organisms may experience diminishing returns of increased reproductive allocation as clutch or litter size increases, affecting current and residual reproductive success. Given existing uncertainty regarding trade-offs between the quantity and quality of offspring, we sought to examine the potential for diminishing returns on increased reproductive allocation in a long-lived species of goose, with a particular emphasis on the effect of position in the laying sequence on offspring quality. 2. To better understand the effects of maternal allocation on offspring survival and growth, we estimated the effects of egg size, timing of breeding, inter- and intra-annual variation, and position in the laying sequence on gosling survival and growth rates of black brent (Branta bernicla nigricans) breeding in western Alaska from 1987–2007. 3. We found that gosling growth rates and survival decreased with position in the laying sequence, regardless of clutch size. Mean egg volume of the clutch a gosling originated from had a positive effect on gosling survival (β = 0.095, 95% CRI: 0.024, 0.165), and gosling growth rates (β = 0.626, 95% CRI: 0.469, 0.738). Gosling survival (β = -0.146, 95% CRI: -0.214, -0.079) and growth rates (β = -1.286, 95% CRI: -1.435, -1.132) were negatively related to hatching date. 4. These findings indicate substantial heterogeneity in offspring quality associated with their position in the laying sequence. They also potentially suggest a trade-off mechanism for females whose total reproductive investment is governed by pre-breeding state. 20-Mar-2020
Data from: Delusions of grandeur: seed count is not a good fitness proxy under individual variation in phenology
The concept of fitness is central to evolutionary biology, yet it is difficult to define and to measure. In plant biology, fitness is often measured as seed count. However, under an array of circumstances, seed count may be a biased proxy of fitness; for example, when individuals vary in allocation to sexual vs. asexual reproduction. A more subtle example, but also likely to be important in natural populations, is when interindividual variation in conditions during development results in variation in offspring quality among seed parents. In monocarpic (semelparous) plants, this is expected to result from variation in effective season length experienced among individuals that reach reproductive maturity at different times. Here, we manipulate growing season length to ask whether seed count is an accurate representation of parental fitness in the monocarpic herb Lobelia inflata. Simple seed count suggests a paradoxical fitness advantage under constrained season length. However, we find that the apparent fitness advantage of a constrained season length is overridden by low relative per-seed fitness. Furthermore, the fitness deficit in the constrained environment is associated primarily with an accelerating decrease in viability and seedling survival in seeds derived from fruits produced progressively later in the season. In this study, the overall fitness value of a seed under a constrained season is 0.774 of that observed under a long season.
Data from: Polyploid plants obtain greater fitness benefits from a nutrient acquisition mutualism
<p>Polyploidy is a key driver of ecological and evolutionary processes in plants, yet little is known about its effects on biotic interactions. This gap in knowledge is especially profound for nutrient acquisition mutualisms, despite the fact that they regulate global nutrient cycles and structure ecosystems. Generalism in mutualistic interactions depends on the range of potential partners (niche breadth), the benefits obtained, and ability to maintain benefits across a variety of partners (fitness plasticity). Here, we determine how each of these is influenced by polyploidy in the legume-rhizobium mutualism. We inoculated a broad geographic sample of natural diploid and autotetraploid alfalfa (<i>Medicago sativa</i>)<i> </i>lineages with a diverse panel of <i>Sinorhizobium </i>bacterial symbionts. To analyze the extent and mechanism of generalism, we measured host growth benefits and functional traits. Autotetraploid plants obtained greater fitness enhancement from mutualistic interactions and were better able to maintain this across diverse rhizobial partners (i.e., low plasticity in fitness) relative to diploids. These benefits were not attributed to increases in niche breadth, but instead reflect increased rewards from investment in the mutualism. Polyploid plants displayed greater generalization in bacterial mutualisms relative to diploids illustrating another axis of advantage for polyploids over diploids.</p>
Data from: Individual and population fitness consequences associated with large carnivore use of residential development
<p><span>Large carnivores are negotiating increasingly developed landscapes, but little is known about how such behavioral plasticity influences their demographic rates and population trends. Some investigators have suggested that the ability of carnivores to behaviorally adapt to human development will enable their persistence, and yet, others have suggested that such landscapes are likely to serve as population sinks or ecological traps. To understand how plasticity in black bear (<i>Ursus americanus</i>) use of residential development influences their population dynamics, we conducted a 6 year study near Durango, Colorado, USA. </span>Using space-use data on individual bears, we examined the influence of use of residential development on annual measures of bear body fat, cub productivity, cub survival and adult female survival, after accounting for variation in natural food availability and individual attributes (e.g., age). We then used our field-based vital rate estimates to parameterize a matrix model that simulated asymptotic population growth for bears using residential development to different degrees. We found that bear use of residential development was highly variable within and across years, with bears increasing their foraging within development when natural foods were scarce. Increased bear use of development was associated with increased body fat and cub productivity, but reduced cub and adult survival.<span> When these effects were simultaneously incorporated into a matrix model </span>we found that the population was projected to decline as bear use of development increased, given that the costs of reduced survival outweighed the benefits of enhanced productivity. Our results provide a mechanistic understanding of how black bear use of residential development exerts opposing effects on different bear fitness traits and a negative effect on population growth, with the magnitude of those effects mediated by variation in environmental conditions. They also highlight the importance of monitoring bear population dynamics, particularly as shifts in bear behavior are likely to drive increases in human-bear conflicts and the perception of growing bear populations. Finally, our work emphasizes the need to consider the demographic viability of large carnivore populations when promoting the coexistence of people and carnivores on shared landscapes.</p>
Data from: Extreme copy number variation at a tRNA ligase gene affecting phenology and fitness in yellow monkeyflowers
Copy number variation (CNV) is a major part of the genetic diversity segregating within populations, but remains poorly understood relative to single nucleotide variation. Here, we report on a tRNA ligase gene (RLG1a) exhibiting unprecedented, and fitness-relevant, CNV within an annual population of the yellow monkeyflower Mimulus guttatus. Variation at RLG1a was associated with multiple traits in pooled population resequencing (PoolSeq) scans of phenotypic and phenological cohorts. Five of 35 (14%) of resequenced inbred lines carried three-copy variants of RLG1a (trip+), and trip+ lines exhibited elevated RLG1a expression. trip+ carriers, in addition to being over-represented in late-flowering and large-flowered PoolSeq populations, flowered later under stressful conditions in a greenhouse experiment (P < 0.05). In early-flowering wild cohorts, we discovered an additional rare variant (high+) that carries 250-300 copies of RLG1a totaling ~5.7Mb, equivalent to 20-40% of a chromosome. Mendelian segregation of diagnostic alleles and qPCR-based copy counts In the progeny of a high+ carrier, indicate that high+ is a single tandem array unlinked from the single copy RLG1a locus in the reference genome. In the wild, high+ carriers had highest fitness in two dry and/or hot years (2015 and 2017; both P < 0.01), while single copy individuals were twice as fecund as either CNV genotype in a lush year (2016: p < 0.005). Our results demonstrate fluctuating selection on CNVs affecting phenological traits in a wild population, suggest that plant tRNA ligases mediate stress-responsive life-history traits, and introduce a novel system for investigating the molecular mechanisms of gene amplification.
Data from: Fitness consequences of interspecific nesting associations among cavity-nesting birds
Interspecific aggregations of prey may provide benefits by mitigating predation risk, but they can also create costs if they increase competition for resources or are more easily detectable by predators. Variation in predation risk and resource availability may influence the occurrence and fitness effects of aggregating in nature. Yet, tests of such possibilities are lacking. Cavity nesting birds provide an interesting test case. They compete aggressively for resources and experience low nest predation rates, which might predict dispersion, but we found they commonly aggregate by sharing nest trees across 19 years of study. Tree sharing was more common when aspen were more abundant and somewhat more common in years with higher nest predation risk. Nest success was higher in shared trees when nest predation risk was higher than average. Ultimately, the costs and benefits of aggregating (nest tree sharing) varied across years and we outline hypotheses for future studies.
Data from: Energetic fitness: field metabolic rates assessed via 3D accelerometry complement conventional fitness metrics
1) Evaluating the fitness of organisms is an essential step towards understanding their responses to environmental change. Connections between energy expenditure and fitness have been postulated for nearly a century. However, testing this premise among wild animals is constrained by difficulties in measuring energy expenditure while simultaneously monitoring conventional fitness metrics such as survival and reproductive output. 2) We addressed this issue by exploring the functional links between field metabolic rate (FMR), body condition, sex, age and reproductive performance in a wild population. 3) We deployed 3D accelerometers on 115 Adélie penguins (Pygoscelis adeliae) during four breeding seasons at one of the largest colonies of this species, Cape Crozier, on Ross Island, Antarctica. The demography of this population has been studied for the past 18 years. From accelerometry recordings, collected for birds of known age and breeding history, we determined the vector of the dynamic body acceleration (VeDBA) and used it as a proxy for FMR. 4) This allowed us to demonstrate relationships between FMR, a breeding quality index (BQI), and body condition. Notably, we found a significant quadratic relationship between mean VeDBA during foraging and BQI for experienced breeders, and individuals in better body condition showed lower rates of energy expenditure. 5) We conclude that using FMR as a fitness component complementary to more conventional fitness metrics will yield greater understanding of evolutionary and conservation physiology.
Parasitoids of leaf herbivores enhance plant fitness and do not alter caterpillar-induced resistance against seed beetles
<p>1. Organisms of the third trophic level can indirectly interact with plants. However, whether parasitoids of herbivores have a positive effect on plant fitness has been controversial. In addition to possible effects on plant fitness, parasitoid-mitigated herbivory can modify plant physiological responses and thereby alter the plant-mediated indirect interactions between different herbivore species. These types of indirect multitrophic interactions remain largely unexplored. Thus, to understand the full effect of the third trophic level on plants, it is necessary to consider the context of the community of interacting species, both herbivores and their enemies.</p> <p>2. Here, we investigated if parasitoids of leaf-feeding caterpillars affect plant fitness (seed quantity and quality) and the consequences for seed-dwelling insects at the second and third trophic levels through plant mediated effects. To test this, we exposed lima bean plants (<i>Phaseolus lunatus</i>), under controlled field conditions, to unparasitized caterpillars (<i>Spodoptera latifascia</i>) or caterpillars that were parasitized by the parasitoid species <i>Cotesia marginiventris</i>. Later in the season, we measured seed production and infestation by seed beetles and their parasitoids.</p> <p>3. We found that parasitoids significantly reduced the leaf damage inflicted by the caterpillars, such that the plants suffered no loss in seed production. Yet, parasitoids had no effect on the emergence of seed beetles (<i>Zabrotes subfasciatus</i> and <i>Acanthoscelides obtectus</i>), which was equally reduced in plants attacked by unparasitized and by parasitized caterpillars. Seeds from undamaged plants were significantly more attacked by <i>Z. subfasciatus</i> beetles. Parasitism rates of seed beetle larvae were similar for all treatments.</p> <p>4. Although parasitized caterpillars did not damage the plants enough to reduce seed production (unlike unparasitized caterpillars), the damage they inflicted induced resistance against other herbivores. Taken together, these results reveal how parasitoids can indirectly enhance plant fitness in the context of the local ecological networks. These findings have significant implications for natural and agricultural systems since they reveal that the indirect interaction between plants and parasitoids can be beneficial in communities with multiple herbivore species.</p>
Data from: Direct effects of a non-native invader erode native plant fitness in the forest understory
1. The direct role of non-native plant invaders in driving negative population- and community-level processes of native species has been recently questioned. Addressing this controversy requires determining quantitatively if invaders negatively affect native population fitness. Because the invasion of non-natives often coincides with other anthropogenic stressors, experiments that partition the putative impact of non-natives from other known stressors and assess their potential synergies are required. While many studies have examined the effects of non-natives on components of native plant performance, studies that decompose the net fitness effects of non-natives from other anthropogenic stressors on population growth rate are lacking. 2. We used six years of detailed demographic data to parameterize a size-dependent integral projection model to examine the individual and combined effects of an allelochemical-producing invader (Alliaria petiolata) and an overabundant ungulate herbivore (Odocoileus virginianus) on the population dynamics of an understory perennial (Trillium erectum). 3. We show that Alliaria consistently and negatively affects the population dynamics of Trillium. Specifically, this invader reduces native population growth rate and alters the size distribution of the population at equilibrium. Alliaria also works in concert with the known negative impacts of overabundant white-tailed deer, illustrating the additive effects of anthropogenic stressors on native plant dynamics. 4. Synthesis. Alliaria's effects on vital rates differed in magnitude and sign across the native's lifecycle, highlighting the importance of detailed demographic analyses. Globally, our study provides novel empirical support for the claim that non-native invasive species can significantly and directly reduce the fitness of native plants.
A Test of the Repeatability of Measurements of Relative Fitness in the Long-Term Evolution Experiment with Escherichia coli
<p>Experimental studies of evolution using microbes have a long tradition, and these studies have increased greatly in number and scope in recent decades. Most such experiments have been short in duration, typically running for weeks or months. A venerable exception, the long-term evolution experiment (LTEE) with <i>Escherichia coli</i> has continued for 30 years and 70,000 bacterial generations. The LTEE has become one of the cornerstones of the field of experimental evolution, in general, and the BEACON Center for the Study of Evolution in Action, in particular. Science laboratories and experiments usually have finite lifespans, but we hope that the LTEE can continue far into the future. There are practical issues associated with maintaining such a long-term experiment. One issue, which we address here, is whether key measurements made at one time and place are reproducible, within reasonable limits, at other times and places. This issue comes to the forefront when one considers moving an experiment like the LTEE from one lab to another. To that end, the Barrick lab at the University of Texas at Austin, measured the fitness values of samples from the 12 LTEE populations at 2,000, 10,000, and 50,000 generations and compared the new data to data previously obtained at Michigan State University. On balance, the datasets agree very well. More generally, this finding shows the value of simplicity in experimental design, such as using a chemically defined growth medium and appropriately storing samples from microbiological experiments. Even so, one must be vigilant in checking assumptions and procedures given the potential for uncontrolled factors (e.g., water quality) to affect outcomes. This vigilance is perhaps especially important for a trait like fitness, which integrates all aspects of organismal performance and may therefore be sensitive to any number of subtle environmental influences.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.