Fitness Gain Research Articles

A life-history perspective on sexual selection in a polygamous species

BackgroundEver since Darwin, evolutionary biologists have studied sexual selection driving differences in appearance and behaviour between males and females. An unchallenged paradigm in such studies is that one sex (usually the male) signals its quality as a mate to the other sex (usually the female), who is choosy in accepting a partner. Here, we hypothesize that in polygamous species these roles change dynamically with the mating status of males and females, depending on direct reproductive costs and benefits of multiple matings, and on sperm competition. We test this hypothesis by assessing fitness costs and benefits of multiple matings in both males and females in a polygamous moth species, as in moths not males but females are the signalers and males are the responders.ResultsWe found that multiple matings confer fitness costs and benefits for both sexes. Specifically, the number of matings did not affect the longevity of males or females, but only 67% of the males and 14% of the females mated successfully in all five nights. In addition, the female’s reproductive output increased with multiple matings, although when paired with a new virgin male every night, more than 3 matings decreased her reproductive output, so that the Bateman gradient for females fit a quadratic model better than a linear model. The male’s reproductive success was positively affected by the number of matings and a linear regression line best fit the data. Simulations of the effect of sperm competition showed that increasing last-male paternity increases the steepness of the male Bateman gradient and thus the male’s relative fitness gain from additional mating. Irrespective of last-male paternity value, the female Bateman gradient is steeper than the male one for up to three matings.ConclusionOur results suggest that choosiness in moths may well change throughout the mating season, with males being more choosy early in the season and females being more choosy after having mated at least three times. This life-history perspective on the costs and benefits of multiple matings for both sexes sheds new light on sexual selection forces acting on sexual signals and responses.

Into the Deep (Sequence) of the Foot-and-Mouth Disease Virus Gene Pool: Bottlenecks and Adaptation during Infection in Naïve and Vaccinated Cattle.

Foot-and-mouth disease virus (FMDV) infects hosts as a population of closely related viruses referred to as a quasispecies. The behavior of this quasispecies has not been described in detail in natural host species. In this study, virus samples collected from vaccinated and non-vaccinated cattle up to 35 days post-experimental infection with FMDV A24-Cruzeiro were analyzed by deep-sequencing. Vaccination induced significant differences compared to viruses from non-vaccinated cattle in substitution rates, entropy, and evidence for adaptation. Genomic variation detected during early infection reflected the diversity inherited from the source virus (inoculum), whereas by 12 days post infection, dominant viruses were defined by newly acquired mutations. Mutations conferring recognized fitness gain occurred and were associated with selective sweeps. Persistent infections always included multiple FMDV subpopulations, suggesting distinct foci of infection within the nasopharyngeal mucosa. Subclinical infection in vaccinated cattle included very early bottlenecks associated with reduced diversity within virus populations. Viruses from both animal cohorts contained putative antigenic escape mutations. However, these mutations occurred during later stages of infection, at which time transmission is less likely to occur. This study improves upon previously published work by analyzing deep sequences of samples, allowing for detailed characterization of FMDV populations over time within multiple hosts.

Francisella novicida and F. philomiragia biofilm features conditionning fitness in spring water and in presence of antibiotics.

Biofilms are currently considered as a predominant lifestyle of many bacteria in nature. While they promote survival of microbes, biofilms also potentially increase the threats to animal and public health in case of pathogenic species. They not only facilitate bacteria transmission and persistence, but also promote spreading of antibiotic resistance leading to chronic infections. In the case of Francisella tularensis, the causative agent of tularemia, biofilms have remained largely enigmatic. Here, applying live and static confocal microscopy, we report growth and ultrastructural organization of the biofilms formed in vitro by these microorganisms over the early transition from coccobacillary into coccoid shape during biofilm assembly. Using selective dispersing agents, we provided evidence for extracellular DNA (eDNA) being a major and conserved structural component of mature biofilms formed by both F. subsp. novicida and a human clinical isolate of F. philomiragia. We also observed a higher physical robustness of F. novicida biofilm as compared to F. philomiragia one, a feature likely promoted by specific polysaccharides. Further, F. novicida biofilms resisted significantly better to ciprofloxacin than their planktonic counterparts. Importantly, when grown in biofilms, both Francisella species survived longer in cold water as compared to free-living bacteria, a trait possibly associated with a gain in fitness in the natural aquatic environment. Overall, this study provides information on survival of Francisella when embedded with biofilms that should improve both the future management of biofilm-related infections and the design of effective strategies to tackle down the problematic issue of bacteria persistence in aquatic ecosystems.

Dissecting Contributions to Efficient Catalysis in the tRNA Modifying Enzyme TilS

Accurate protein synthesis is essential for cell viability, as mistranslation events can affect protein structure, function, and regulation. Bacteria do not translate the rare AUA isoleucine codon with a tRNAIleUAU, as this would wobble pair with the AUG methionine codon and lead to translational ambiguity. Instead, most bacteria use a lysidine modification at the tRNAIle2 wobble position. tRNA isoleucine lysidine synthetase (TilS) installs a lysidine moiety at the wobble position of tRNAIle2CAU, resulting in a tRNAIle2LAU that preferentially pairs with the AUA codon, resulting in accurate charging of the tRNA with isoleucine and decoding at the ribosome. Evolved mutants of Burkholderia cenocepacia TilS have been observed that contribute to a gain of fitness in nutrient-depleted media. Despite the gain of fitness observed, the mutants display a loss of lysidinylation function both in vitro and in vivo. We target catalytically relevant regions of TilS for mutagenesis and functional assays, and model enzyme dynamics in silico. Using all of this knowledge in correspondence, the contribution of these evolutionary mutants can be elucidated.

Transmission potential of paromomycin-resistant Leishmania infantum and Leishmania donovani.

Former studies demonstrated quick selection of paromomycin resistance for Leishmania infantum and Leishmania donovani accompanied by increased fitness. The present study aimed to interpret these findings in an epidemiological context by comparing infection of WT and experimentally derived paromomycin-resistant strains in the sand fly vector. Depending on the Leishmania species, Lutzomyia longipalpis and Phlebotomus perniciosus or Phlebotomus argentipes sand flies were artificially infected with procyclic promastigotes of WT and paromomycin-resistant L. infantum (MHOM/FR/96/LEM3323-cl4) or L. donovani (MHOM/NP/03/BPK275/0-cl18). The infection rate and gut/stomodeal valve colonization were determined to monitor parasite phenotypic behaviour within the vector. The impact of the previously described gain of fitness in the vertebrate host on infectivity for the vector was assessed by feeding L. longipalpis on Syrian golden hamsters heavily infected with either WT or paromomycin-resistant parasites. WT and paromomycin-resistant Leishmania of both species behaved similarly in terms of infection and parasite location within the studied sand fly species. Blood feeding on infected hamsters did not reveal differences in acquisition of WT and paromomycin-resistant parasites, despite the higher organ burdens observed for the paromomycin-resistant strain. Strains remained resistant after passage in the vector. Although paromomycin-resistant parasites show an increased parasite fitness in vitro and in laboratory rodents, the intrinsic infection potential of paromomycin-resistant parasites remains unaltered in the sand fly. Of importance is the fact that paromomycin-resistant Leishmania are able to complete development in the natural vectors and produce stomodeal infection with metacyclic forms, which clearly suggests their potential to spread and circulate in nature.

The Effect of Population Bottleneck Size and Selective Regime on Genetic Diversity and Evolvability in Bacteria.

Population bottlenecks leading to a drastic reduction of the population size are common in the evolutionary dynamics of natural populations; their occurrence is known to have implications for genome evolution due to genetic drift, the consequent reduction in genetic diversity, and the rate of adaptation. Nevertheless, an empirical characterization of the effect of population bottleneck size on evolutionary dynamics of bacteria is currently lacking. In this study, we show that selective conditions have a stronger effect on the evolutionary history of bacteria in comparison to population bottlenecks. We evolved Escherichia coli populations under three different population bottleneck sizes (small, medium, and large) in two temperature regimes (37 °C and 20 °C). We find a high genetic diversity in the large in comparison to the small bottleneck size. Nonetheless, the cold temperature led to reduced genetic diversity regardless the bottleneck size; hence, the temperature has a stronger effect on the genetic diversity in comparison to the bottleneck size. A comparison of the fitness gain among the evolved populations reveals a similar pattern where the temperature has a significant effect on the fitness. Our study demonstrates that population bottlenecks are an important determinant of bacterial evolvability; their consequences depend on the selective conditions and are best understood via their effect on the standing genetic variation.

Evaluating the Role of Past Clinical Information on Risk Adjustment.

The objective of this study was to evaluate whether incorporating historical clinical information beyond 1 year improves risk adjustment. Administrative data from the Department of Veterans Affairs and Medicare (for veterans concurrently enrolled in Medicare) for fiscal years (FYs) 2011-2015. We regressed total annual costs on Medicare hierarchical condition category indicators and risk scores for FY 2015 in both a concurrent and a prospective model using 5-fold cross-validation. Regressions were repeated incorporating clinical information from FY 2011 to 2015. Model fit was appraised using R and mean squared predictive error (MSPE). All veterans affairs users (n=3,254,783) with diagnostic information FY 2011-2015. In a concurrent model, adding additional years of historical clinical information (FY 2011-2014) did not result in substantive gains in fit (R from 0.671 to 0.673) or predictive capability (MSPE from 1956 to 1950). In a prospective model, adding additional years of historical clinical information also did not result in substantive gains in fit (R from 0.334 to 0.344) or predictive capability (MSPE from 3988 to 3940). Incorporating historical clinical information yielded no material gain in risk adjustment fit.

Food or host: do physiological state and flower type affect foraging decisions of parasitoids?

Within the optimal foraging theory framework, parasitoids constitute ideal models to elucidate combined physiological and environmental determinism of foraging behavior between current and future fitness gains. Parasitoid females need hosts to lay eggs for their reproduction (immediate gain), but also sugar food resources for their survival (future gain). According to theoretical models and previous empirical studies, fed females should favor host foraging, whereas females with lower energetic reserves should search for food. Surprisingly, the influence of mating status and food quality has not been considered, whereas they may both constitute major factors altering animals’ choices between reproducing and feeding. We tested decision-making on Aphidius rhopalosiphi parasitoid females with different life expectancy levels (as set by recent feeding history) and mating status, using two flower species with contrasted attractiveness and nectar suitability. Interestingly, all fed and unfed females with different expected lifetime levels favored reproduction over nutrition since they are mated. This could be explained by their reproductive status that appeared to be the main determinant of their foraging decisions. For a given expected lifetime, mated females favored more reproduction whereas unmated ones favored food. Physiological status of females (mating and lifetime expectancy) did not interact with flower species on their foraging decisions nor did it modify their preferences, as they always favored the most attractive flower, which does not have the best nectar. These results highlight the need for more empirical studies to evaluate the interactions between different intrinsic factors and to carefully consider the mating status in model assumptions, as it influences foraging behavior between immediate and future fitness gains. Parasitic wasps need hosts to lay eggs for their reproduction (immediate fitness gain) and sugar resources for their survival (future fitness gain). Empirical studies and related theoretical models about foraging decisions of parasitic wasps between current and future gains included influences of energetic and resource availability constrains. We examined assumptions used by those mathematical models by empirically testing two new factors, food qualities provided by two nectar provisioning flower species with contrasted functional traits, which had surprisingly no impact on decision-making, and mating status which we showed to play a decisive role on decision-making between food or host resources. These factors should henceforth be considered in model assumptions or in models themselves to realize accurate predictions and to provide a better understanding of foraging decisions made by female parasitic wasps.

Fitness Gain of Individually Sensed Information by Cells

Mutual information and its causal variant, directed information, have been widely used to quantitatively characterize the performance of biological sensing and information transduction. However, once coupled with selection in response to decision-making, the sensing signal could have more or less evolutionary value than its mutual or directed information. In this work, we show that an individually sensed signal always has a better fitness value, on average, than its mutual or directed information. The fitness gain, which satisfies fluctuation relations (FRs), is attributed to the selection of organisms in a population that obtain a better sensing signal by chance. A new quantity, similar to the coarse-grained entropy production in information thermodynamics, is introduced to quantify the total fitness gain from individual sensing, which also satisfies FRs. Using this quantity, the optimizing fitness gain of individual sensing is shown to be related to fidelity allocations for individual environmental histories. Our results are supplemented by numerical verifications of FRs, and a discussion on how this problem is linked to information encoding and decoding.

Trait-based functional dietary analysis provides a better insight into the foraging ecology of bats.

The degree of trophic specialization determines the ability of predators to cope with changing foraging conditions, but in predators that prey on hundreds of species it is challenging to assess, especially when prey identity varies among predator individuals and across space and time. Here, we test the hypothesis that a bat species foraging on flying insects like moths will show ample flexibility in trophic niche, and this irrespective of phylogenetic relationships among moths, so as to cope with a high diversity of prey types that vary across seasons. We predict that individual bats will show functional dietary differences consistent with energetic requirements and hunting skills. We used DNA metabarcoding to determine the diet of 126 Mediterranean horseshoe bats (Rhinolophus euryale) from two different sites during three seasons. Simultaneously, we measured moth availability and characterized the traits of 290 moth taxa. Next, we explored the relationship between phylogeny and traits of all consumed and available moth taxa. Finally, we assessed the relationship between individual traits of bats and traits related to prey profitability, for which we used the RLQ and fourth-corner statistical techniques. Seasonality was the main factor explaining the functional dietary variation in adult bats, with moths consumed irrespective of their phylogenetic relationships. While adults consumed moths with a broad range in wing loading, body mass and echolocation detection ability, juveniles consumed slower, smaller and lighter moths, which suggests that young individuals may undergo some fitness gain and/or psychomotor learning process during which they would acquire more effective foraging skills. Our approach revealed a degree of functional flexibility in the trophic niche previously unknown for an insectivorous bat. Rhinolophus euryale consumed a wide variety of moth taxa differing in profitability throughout seasons and between ontogenetic stages. We showed the validity of trait-based approaches to gain new insights in the trophic specialization of predators consuming hundreds of species of prey.

Spontaneous mutations in a regulatory gene induce phenotypic heterogeneity and adaptation of Ralstonia solanacearum to changing environments.

An evolution experiment with the bacterial plant pathogen Ralstonia solanacearum revealed that several adaptive mutations conferring enhanced fitness in plants arose in the efpR gene encoding a regulator of virulence and metabolic functions. In this study, we found that an efpR mutant systematically displays colonies with two morphotypes: the type S ('smooth', similar to the wild type) and the type EV ('efpR variant'). We demonstrated that the efpH gene, a homologue of efpR, plays a key role in the control of phenotypic heterogeneity, the ΔefpR-ΔefpH double mutant being stably locked into the EV type. Using mixed infection assays, we demonstrated that the type EV is metabolically more proficient than the type S and displays fitness gain in specific environments, whereas the type S has a better fitness into the plant environment. We provide evidence that this efpR-dependent phenotypic heterogeneity is a general feature of strains of the R. solanacearum species complex and could occur in natural conditions. This study highlights the potential role of phenotypic heterogeneity in this plant pathogen as an adaptive trait to changing environments.

Larvae promote a decline in the harvesting of myrmecochorous seeds by Myrmica rubra ants

Non-granivorous ant species that contribute to seed dispersal (myrmecochory sensu stricto) are assumed to benefit from the larval consumption of elaiosomes, the lipid-rich appendages of myrmecochorous seeds. It is, however, questionable whether this ant–plant interaction is truly mutualistic, since some ant partners do not show a clear-cut fitness gain and may cease the harvesting of myrmecochorous seeds over time. In particular, the role of ant larvae as potential consumers of seed elaiosomes is not yet fully understood. In this study, we investigated how the number of larvae influences the foraging responses of the red ant Myrmica rubra to Viola odorata myrmecochorous seeds and to Drosophila melanogaster prey. Ant workers retrieved less elaiosome-bearing seeds than prey and the harvesting of seeds remained low, even in the presence of larvae. Furthermore, while the ant colonies continued to collect prey over successive foraging events, the retrieval of myrmecochorous seeds decreased, most particularly in colonies containing a large number of larvae. Brood exposure to diaspores also declined, with very few larvae coming into contact with seeds. Our results suggest that the role of larvae as elaiosome consumers should be reconsidered and that larvae may provide workers with cues about the poor palatability of V. odorata diaspores, thereby altering the stability of this ant–plant interaction.

Cardio-Oncology Rehabilitation to Manage Cardiovascular Outcomes in Cancer Patients and Survivors: A Scientific Statement From the American Heart Association.

Cardiovascular disease is a competing cause of death in patients with cancer with early-stage disease. This elevated cardiovascular disease risk is thought to derive from both the direct effects of cancer therapies and the accumulation of risk factors such as hypertension, weight gain, cigarette smoking, and loss of cardiorespiratory fitness. Effective and viable strategies are needed to mitigate cardiovascular disease risk in this population; a multimodal model such as cardiac rehabilitation may be a potential solution. This statement from the American Heart Association provides an overview of the existing knowledge and rationale for the use of cardiac rehabilitation to provide structured exercise and ancillary services to cancer patients and survivors. This document introduces the concept of cardio-oncology rehabilitation, which includes identification of patients with cancer at high risk for cardiac dysfunction and a description of the cardiac rehabilitation infrastructure needed to address the unique exposures and complications related to cancer care. In this statement, we also discuss the need for future research to fully implement a multimodal model of cardiac rehabilitation for patients with cancer and to determine whether reimbursement of these services is clinically warranted.

Winners have higher pre-copulatory mating success but losers have better post-copulatory outcomes.

In many animals, the outcomes of competitive interactions can have lasting effects that influence an individual's reproductive success and have important consequences for the strength and direction of evolution via sexual selection. In the fruit fly, Drosophila melanogaster, males that have won previous contests are more likely to win in subsequent conflicts and losers are more likely to lose (winner-loser effects), but the direct fitness consequences and genetic underpinnings of this plasticity are poorly understood. Here, we tested how male genotype and the outcomes of previous male-male conflicts influence male pre- and post-copulatory success. We quantified pre-copulatory success in a choice and no-choice context, and post-copulatory success by quantifying ejaculate offensive and defensive ability. We found that winners have higher reproductive success compared to losers in both pre-copulatory scenarios. However, losers consistently mated for a longer duration, boosted female fecundity and had an increased paternity share when they were the first males to mate, suggesting increased investment into post-copulatory mechanisms. Finally, by using clonal hybrids from the Drosophila Genetic Reference Panel, we documented that genetic variation explained a sizeable proportion of the observed differences between lines, and of the interaction between line and winner and loser effects. Our results place the behavioural data on winner-loser effects in an evolutionary context by documenting the potential fitness gain to males from altering their reproductive strategy based on fighting experience. Our data may also explain the presence and maintenance of trade-offs between different male reproductive strategies.

Conflict within species determines the value of a mutualism between species.

Mutually beneficial interactions between species play a key role in maintaining biodiversity and ecosystem function. Nevertheless, such mutualisms can erode into antagonistic interactions. One explanation is that the fitness costs and benefits of interacting with a partner species vary among individuals. However, it is unclear why such variation exists. Here, we demonstrate that social behavior within species plays an important, though hitherto overlooked, role in determining the relative fitness to be gained from interacting with a second species. By combining laboratory experiments with field observations, we report that conflict within burying beetles Nicrophorus vespilloides influences the fitness that can be gained from interacting with the mite Poecilochirus carabi. Beetles transport these mites to carrion, upon which both species breed. We show that mites help beetles win intraspecific contests for this scarce resource: mites raise beetle body temperature, which enhances beetle competitive prowess. However, mites confer this benefit only upon smaller beetles, which are otherwise condemned by their size to lose contests for carrion. Larger beetles need no assistance to win a carcass and then lose reproductive success when breeding alongside mites. Thus, the extent of mutualism is dependent on an individual's inability to compete successfully and singlehandedly with conspecifics. Mutualisms degrade into antagonism when interactions with a partner species start to yield a net fitness loss, rather than a net fitness gain. This study suggests that interactions with conspecifics determine where this tipping point lies.

Environment-dependent fitness gains can be driven by horizontal gene transfer of transporter-encoding genes

Many microbes acquire metabolites in a "feeding" process where complex polymers are broken down in the environment to their subunits. The subsequent uptake of soluble metabolites by a cell, sometimes called osmotrophy, is facilitated by transporter proteins. As such, the diversification of osmotrophic microorganisms is closely tied to the diversification of transporter functions. Horizontal gene transfer (HGT) has been suggested to produce genetic variation that can lead to adaptation, allowing lineages to acquire traits and expand niche ranges. Transporter genes often encode single-gene phenotypes and tend to have low protein-protein interaction complexity and, as such, are potential candidates for HGT. Here we test the idea that HGT has underpinned the expansion of metabolic potential and substrate utilization via transfer of transporter-encoding genes. Using phylogenomics, we identify seven cases of transporter-gene HGT between fungal phyla, and investigate compatibility, localization, function, and fitness consequences when these genes are expressed in Saccharomyces cerevisiae Using this approach, we demonstrate that the transporters identified can alter how fungi utilize a range of metabolites, including peptides, polyols, and sugars. We then show, for one model gene, that transporter gene acquisition by HGT can significantly alter the fitness landscape of S. cerevisiae We therefore provide evidence that transporter HGT occurs between fungi, alters how fungi can acquire metabolites, and can drive gain in fitness. We propose a "transporter-gene acquisition ratchet," where transporter repertoires are continually augmented by duplication, HGT, and differential loss, collectively acting to overwrite, fine-tune, and diversify the complement of transporters present in a genome.

Application of variable selection and dimension reduction on predictors of MSE\u2019s development

Nature create variables using its character component, and variables are sharing characters from a vary small to relatively large scale. This results, variables to have from a vary different to a more similar character, and leads to have a relation ship. Literature suggested different relation measures based on the nature of variable and type of relation ship exist. Today, due to having high variety of frequently produced large data size, currently suggested variable filtering and selection methods have gaps to full fill the need. This research desires to fill this gap by comparing literature suggested methods to finding out a better variable selection and dimension reduction methods. The result from regression analysis using all literature suggested factors shows that none of the predictors for development status of enterprise are significant, and only 10 predictors for number of employer in an enterprise are significant out of 81 factors. Since, variable selection and dimension reduction methods are applied to find out predictors of a response by removing variable redundancy, and complexity of incorporating large number variable. Based on statistical power, for the results from variable selection methods, specially association and correlation methods showed that, CANOVA more efficiently detects non-linear or non-monotonic correlation between a continuous–continuous and a continuous-categorical variables. Spearman’s correlation coefficient more efficiently detects a monotonic correlation between a continuous with a continuous, and a continuous with a categorical variable. Pearson correlation coefficient more efficiently detects the linear correlation between continuous variables. MIC efficiently detects non-linear or non-monotonic relation between continuous variables. Chi-square test of independence efficiently detects relation between a continuous with a continuous, and categorical with categorical variables, but the non linear or non monotonic relation between a continuous with a categorical are not well detected. On the other hand, the result from lasso and stepwise methods reveals that, the relation between the predictor and response due to interaction effect not detected by correlation and association methods are detected by stepwise variable selection method, and the multicollinearity is detected and removed by lasso method. Regressing the response variable “number of employer in an enterprise” based on variables selected by lasso and stepwise method does bring greater model fitness (based on adjusted R-squared value) than variables selected by association and correlation methods. Similarly, regressing the response variable “development status of an enterprise” based on variables selected by association and correlation methods does bring 12 significant variables, where none of variables are significant from variables selected by lasso and stepwise methods. As a result, 51 predictors for number of employment in an enterprise, and 40 predictors for development status of an enterprise are detected as significantly related variables. And, lasso and stepwise methods are preferred to select predictors of a continuous response variable “number of employers in an enterprise”, and association and correlation methods are preferred to select predictors of a categorical response variable “development status of an enterprise”. Finally, the reduced regression models result reveals that, 20 predictors have causal relation with number of employment in an enterprise, and 12 predictors have causal relation with development status of an enterprise. On the other hand, based on model fitness, information lost, and number of significant factors, principal factor is preferred and applied in dimension reduction for a categorical response variable “development status of an enterprise”, and factor score based regression is preferred and applied for a continuous response variable “number of employers in an enterprise”. However, the comparison of the results in variable selection and dimension reduction indicates that, variable selection methods gave more gain in model fitness than dimension reduction methods. Hence, the suggested variable selection methods are more preferred than dimension reduction methods, and applied to find out predictors. In general, the suggested procedure for variable selection methods are recommended when small number of variables are studied, and the suggested dimension reduction methods are recommended for large number of variant variables (Big data case).

Efficacy and Effectiveness of Mobile Health Technologies for Facilitating Physical Activity in Adolescents: Scoping Review.

BackgroundIncreasing physical activity (PA) levels in adolescents aged 12 to 18 years is associated with prevention of unhealthy weight gain and improvement in cardiovascular fitness. The widespread availability of mobile health (mHealth) and wearable devices offers self-monitoring and motivational features for increasing PA levels and improving adherence to exercise programs.ObjectiveThe aim of this scoping review was to identify the efficacy or effectiveness of mHealth intervention strategies for facilitating PA among adolescents aged 12 to 18 years.MethodsWe conducted a systematic search for peer-reviewed studies published between 2008 and 2018 in the following electronic databases: PubMed, Google Scholar, PsychINFO, or SportDiscus. The search terms used included mHealth or “mobile health” or apps, “physical activity” or exercise, children or adolescents or teens or “young adults” or kids, and efficacy or effectiveness. Articles published outside of the date range (July 2008 to October 2018) and non-English articles were removed before abstract review. Three reviewers assessed all abstracts against the inclusion and exclusion criteria. Any uncertainties or differences in opinion were discussed as a group. The inclusion criteria were that the studies should (1) have an mHealth component, (2) target participants aged between 12 and 18 years, (3) have results on efficacy or effectiveness, and (4) assess PA-related outcomes. Reviews, abstracts only, protocols without results, and short message service text messaging–only interventions were excluded. We also extracted potentially relevant papers from reviews. At least 2 reviewers examined all full articles for fit with the criteria and extracted data for analysis. Data extracted from selected studies included study population, study type, components of PA intervention, and PA outcome results.ResultsOverall, 126 articles were initially identified. Reviewers pulled 18 additional articles from excluded review papers. Only 18 articles were passed onto full review, and 16 were kept for analysis. The included studies differed in the sizes of the study populations (11-607 participants), locations of the study sites (7 countries), study setting, and study design. Overall, 5 mHealth intervention categories were identified: website, website+wearable, app, wearable+app, and website+wearable+app. The most common measures reported were subjective weekly PA (4/13) and objective daily moderate-to-vigorous PA (5/13) of the 19 different PA outcomes assessed. Furthermore, 5 of 13 studies with a control or comparison group showed a significant improvement in PA outcomes between the intervention group and the control or comparison group. Of those 5 studies, 3 permitted isolation of mHealth intervention components in the analysis.ConclusionsPA outcomes for adolescents improved over time through mHealth intervention use; however, the lack of consistency in chosen PA outcome measures, paucity of significant outcomes via between-group analyses, and the various study designs that prevent separating the effects of intervention components calls into question their true effect.

One problem, too many solutions: How costly is honest signalling of need?

The “cost of begging” is a prominent prediction of costly signalling theory, suggesting that offspring begging has to be costly in order to be honest. Seminal signalling models predict that there is a unique equilibrium cost function for the offspring that results in honest signalling and this cost function must be proportional to parent’s fitness loss. This prediction is only valid if signal cost and offspring condition is assumed to be independent. Here we generalize these models by allowing signal cost to depend on offspring condition. We demonstrate in the generalized model that any signal cost proportional to the fitness gain of the offspring also results in honest signalling. Moreover, we show that any linear combination of the two cost functions (one proportional to parent’s fitness loss, as in previous models, the other to offspring’s fitness gain) also leads to honest signalling in equilibrium, yielding infinitely many solutions. Furthermore, we demonstrate that there exist linear combinations such that the equilibrium cost of signals is negative and the signal is honest. Our results show that costly signalling theory cannot predict a unique equilibrium cost in signalling games of parent-offspring conflicts if signal cost depends on offspring condition. It follows, contrary to previous claims, that the existence of parent-offspring conflict does not imply costly equilibrium signals. As an important consequence, it is meaningless to measure the “cost of begging” as long as the dependence of signal cost on offspring condition is unknown. Any measured equilibrium cost in case of condition-dependent signal cost has to be compared both to the parent’s fitness loss and to the offspring’s fitness gain in order to provide meaningful interpretation.

Phenological and fitness responses to climate warming depend upon genotype and competitive neighbourhood in Arabidopsis thaliana

Abstract Increasing temperatures during climate change are known to alter the phenology across diverse plant taxa, but the evolutionary outcomes of these shifts are poorly understood. Moreover, plant temperature‐sensing pathways are known to interact with competition‐sensing pathways, yet there remains little experimental evidence for how genotypes varying in temperature responsiveness react to warming in realistic competitive settings. We compared flowering time and fitness responses to warming and competition for two near‐isogenic lines (NILs) of Arabidopsis thaliana transgressively segregating temperature‐sensitive and temperature‐insensitive alleles for major‐effect flowering time genes. We grew focal plants of each genotype in intraspecific and interspecific competition in four treatments contrasting daily temperature profiles in summer and fall under contemporary and warmed conditions. We measured phenology and fitness of focal plants to quantify plastic responses to season, temperature and competition and the dependence of these responses on flowering time genotype. The temperature‐insensitive NIL was constitutively early flowering and less fit, except in a future‐summer climate in which its fitness was higher than the later flowering, temperature‐sensitive NIL in low competition. The late‐flowering NIL showed accelerated flowering in response to intragenotypic competition and to increased temperature in the summer but delayed flowering in the fall. However, its fitness fell with rising temperatures in both seasons, and in the fall its marginal fitness gain from decreasing competition was diminished in the future. Functional alleles at temperature‐responsive genes were necessary for plastic responses to season, warming and competition. However, the plastic genotype was not the most fit in every experimental condition, becoming less fit than the temperature‐canalized genotype in the warm summer treatment. Climate change is often predicted to have deleterious effects on plant populations, and our results show how increased temperatures can act through genotype‐dependent phenology to decrease fitness. Furthermore, plasticity is not necessarily adaptive in rapidly changing environments since a nonplastic genotype proved fitter than a plastic genotype in a warming climate treatment. A plain language summary is available for this article.