scholarly journals Survival of the unfittest: Metabolic trade-offs expose unforeseen benefits of plasmid carriage

2019 ◽  
Author(s):  
Carlos Reding
Keyword(s):  
Reproductive Success ◽  
Tetracycline Resistance ◽  
Reproductive Traits ◽  
Trade Off ◽  
Trade Offs ◽  
Transmissible Plasmid ◽  
Underlying Principle ◽  
Wild Type Counterpart ◽  
Plasmid Carriage ◽  
Competition Assays

Population genetics theory defines fitness as reproductive success: Mutants reproducing faster than their wild-type counterpart are favoured by selection. Otherwise, the mutations are lost. Here I show that unfit mutants can thrive when selection favours non-reproductive traits if they engage in a trade-off with fitness. I co-maintained two constructs of Escherichia coli, with and without a non-transmissible plasmid, for more than 80 generations in competition assays that favoured yield. Plasmid carriage prompted a known metabolic trade-off in the bacterium between growth rate per capita—reproductive success—and yield. Importantly the plasmid carries a tetracycline-resistance gene, tet(36). By favouring yield, cells harbouring the plasmid preserved it without exposure to the antibiotic. Unsurprisingly, these cells outgrew their fitter plasmid-free competitor with trace low tetracycline concentrations. Fitness competition assays are widely used, but experimental validation of their underlying principle is rare. These assays are the ‘gold-standard’ in genetics, but my work suggests their reliability may be lower than previously thought.

scholarly journals Beyond size–number trade-offs: clutch size as a maternal effect

2009 ◽  
Vol 364 (1520) ◽  
pp. 1097-1106 ◽  
Author(s):  
Gregory P Brown ◽  
Richard Shine
Keyword(s):  
Clutch Size ◽  
Experimental Studies ◽  
Reproductive Traits ◽  
Nest Site Selection ◽  
The Body ◽  
Offspring Size ◽  
Trade Off ◽  
Trade Offs ◽  
Size Number ◽  
Hatchling Size

Traditionally, research on life-history traits has viewed the link between clutch size and offspring size as a straightforward linear trade-off; the product of these two components is taken as a measure of maternal reproductive output. Investing more per egg results in fewer but larger eggs and, hence, offspring. This simple size–number trade-off has proved attractive to modellers, but our experimental studies on keelback snakes ( Tropidonophis mairii , Colubridae) reveal a more complex relationship between clutch size and offspring size. At constant water availability, the amount of water taken up by a snake egg depends upon the number of adjacent eggs. In turn, water uptake affects hatchling size, and therefore an increase in clutch size directly increases offspring size (and thus fitness under field conditions). This allometric advantage may influence the evolution of reproductive traits such as growth versus reproductive effort, optimal age at female maturation, the body-reserve threshold required to initiate reproduction and nest-site selection (e.g. communal oviposition). The published literature suggests that similar kinds of complex effects of clutch size on offspring viability are widespread in both vertebrates and invertebrates. Our results also challenge conventional experimental methodologies such as split-clutch designs for laboratory incubation studies: by separating an egg from its siblings, we may directly affect offspring size and thus viability.

scholarly journals Genetic trade-offs between male reproductive traits in Drosophila melanogaster

2018 ◽  
Vol 14 (10) ◽  
pp. 20180474 ◽  
Author(s):  
David C. S. Filice ◽  
Tristan A. F. Long
Keyword(s):  
Drosophila Melanogaster ◽  
Reproductive Success ◽  
Selection Pressure ◽  
Reproductive Traits ◽  
Male Reproductive Success ◽  
Short Term ◽  
Trade Offs ◽  
Sexual Traits ◽  
Stimulation Of

In Drosophila melanogaster , males engage in both extensive pre- and post-copulatory competition for the opportunity to mate with females and subsequently sire offspring. The selection pressure for increased male reproductive success has resulted in the evolution of a wide diversity of sexual traits. However, despite strong selection, individuals often exhibit considerable phenotypic variation in the expression of these traits, and it is unclear if any of this variation is owing to underlying genetic trade-offs. Here, using hemiclonal flies, we examine how male reproductive success covaries with their ability to induce long-term stimulation of oogenesis and oviposition in their mates, and how this relationship may change over time. We found that males from hemiclone lines with phenotypes that were more successful in a short-term reproductive ‘scramble’ environment were less effective at stimulating long-term fecundity in females. Furthermore, we observed that males from hemiclone lines which showed the most improvement over a longer reproductive interaction period also tended to stimulate higher long-term fecundity in females. Together, these results indicate the presence of genetic trade-offs between different male reproductive traits and offer insights into the maintenance of their variation.

scholarly journals Parents face quantity–quality trade-offs between reproduction and investment in offspring in Iceland

2016 ◽  
Vol 3 (5) ◽  
pp. 160087 ◽  
Author(s):  
Robert Francis Lynch
Keyword(s):  
Reproductive Success ◽  
Evolutionary Biology ◽  
Fundamental Problem ◽  
Lifetime Reproductive Success ◽  
Trade Off ◽  
Evolutionary Conflict ◽  
Trade Offs ◽  
Fitness Consequences ◽  
Using Data ◽  
Primary Impact

How to optimally allocate time, energy and investment in an effort to maximize one's reproductive success is a fundamental problem faced by all organisms. This effort is complicated when the production of each additional offspring dilutes the total resources available for parental investment. Although a quantity–quality trade-off between producing and investing in offspring has long been assumed in evolutionary biology, testing it directly in humans is difficult, partly owing to the long generation time of our species. Using data from an Icelandic genealogy (Íslendingabók) over two centuries, I address this issue and analyse the quantity–quality trade-off in humans. I demonstrate that the primary impact of parents on the fitness of their children is the result of resources and or investment, but not genes. This effect changes significantly across time, in response to environmental conditions. Overall, increasing reproduction has negative fitness consequences on offspring, such that each additional sibling reduces an individual's average lifespan and lifetime reproductive success. This analysis provides insights into the evolutionary conflict between producing and investing in children while also shedding light on some of the causes of the demographic transition.

scholarly journals Ageing and senescence across reproductive traits and survival in superb fairy-wrens (Malurus cyaneus)

2019 ◽  
Author(s):  
Eve Cooper ◽  
Timothée Bonnet ◽  
Helen Osmond ◽  
Andrew Cockburn ◽  
Loeske E. B. Kruuk
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Age Of Onset ◽  
Reproductive Traits ◽  
Individual Variability ◽  
Multiple Traits ◽  
Long Term Study ◽  
Trade Offs ◽  
Age Related ◽  
Malurus Cyaneus

Why do senescence rates of fitness-related traits often vary dramatically? By considering the full ageing trajectories of multiple traits we can better understand how trade-offs and life-history shapes the unique evolution of senescence rates within a population. Here, we examine age-related changes in survival and six reproductive traits in both sexes using a long-term study of a wild population of a cooperatively-breeding songbird, the superb fairy-wren (Malurus cyaneus). We compare ageing patterns between traits by estimating standardized rates of maturation, the age of onset of senescence and rates of senescence, while controlling for confounding factors reflecting individual variability in life-history. We found striking differences in ageing and senescence patterns between survival and reproduction, and between the sexes. In both sexes, rates of survival started to decline from maturity onwards. In contrast, all reproductive traits showed improvements into early adulthood and many showed little or no evidence of senescence. Male reproductive ageing appeared to be driven by sexual selection, with extra-group reproductive success and sexually-selected plumage phenology showing much greater change with age than did within-group reproductive success. We discuss how the superb fairy-wrens’ complex life history may contribute to the disparate ageing patterns in this species.

Seasonally contrasting life-history strategies in the land snail Cornu aspersum: physiological and ecological implications

2010 ◽  
Vol 88 (10) ◽  
pp. 995-1002 ◽  
Author(s):  
A. Nicolai ◽  
J. Filser ◽  
V. Briand ◽  
M. Charrier
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Reproductive Strategies ◽  
Energy Content ◽  
Reproductive Traits ◽  
Land Snails ◽  
Life History Strategies ◽  
Hatching Rate ◽  
Trade Offs ◽  
Cornu Aspersum

When a life history is characterized by both seasonality in reproduction and seasonality in offspring fitness, trade-offs in reproductive traits might be adjustments to seasonal time constraints to optimize reproductive success. Therefore, we compared in the laboratory the trade-offs in reproductive traits between early (after maturity) and delayed (after dormancy) reproduction in young land snails Cornu aspersum (Müller, 1774) (syn. Helix aspersa ), depending on food energy content. We also investigated the maternal investment in reproductive output in both breeding periods. After attaining maturity, snails produced single clutches with many small eggs, which resulted, in contrast to previous studies, in large offspring with a low hatching rate owing to high within-clutch cannibalism. The young cannibals may have a higher survival probability in the following hibernation. Snails starting to reproduce after hibernation had smaller clutches of larger eggs, resulting in high quantity of lighter offspring. The clutch mass was positively correlated with maternal mass in snails reproducing after having attained maturity and negatively correlated in snails reproducing after hibernation. Multiple oviposition occurred only after hibernation, thereby enhancing reproductive success. An energy-rich diet did not affect reproductive strategies. Further studies should focus on seasonal plasticity of reproductive strategies in natural populations of C. aspersum and investigate survival probabilities of breeders and juveniles in an evolutionary context.

Reproductive trade-offs in the elapid snakes Austrelaps superbus and Austrelaps ramsayi

2001 ◽  
Vol 79 (6) ◽  
pp. 1030-1037 ◽  
Author(s):  
Detlef H Rohr
Keyword(s):  
Litter Size ◽  
Reproductive Traits ◽  
Offspring Size ◽  
Temporal Separation ◽  
Trade Off ◽  
Trade Offs ◽  
Partial Correlations ◽  
Highly Correlated ◽  
The Times ◽  
Gravid Females

Reproductive traits and the trade-offs among these traits were examined in two venomous terrestrial elapid snakes, the Australian lowland copperhead, Austrelaps superbus, and the Australian highland copperhead, Austrelaps ramsayi. Sampling was difficult, so gravid females had to be held in captivity for up to several months prior to parturition. Analyses showed that captivity affected the time of parturition and maternal body condition, but it had no apparent effect on offspring traits. The results were corroborated by conducting partial follicular ablations in gravid A. superbus with fully yolked follicles. While these females gave birth earlier than unmanipulated females, offspring size was highly correlated with follicular size at the time of ablation and fell within the size range observed in the other females. This suggests that offspring size is fixed by the time follicles are fully yolked. Among unmanipulated females, reproductive traits were similar in A. superbus and A. ramsayi, but relationships among the traits differed. In the A. superbus sample, the trade-off between litter size and offspring size only became apparent after partial correlations, presumably because spring foraging obscured this relationship. In the A. ramsayi sample, however, the trade-off between litter size and offspring size was very pronounced. At this locality, there was no evidence of spring foraging, and snakes had fully developed follicles before or soon after they emerged from hibernation. This reduces the temporal separation between the times when litter size and offspring size are fixed and may allow greater control over the distribution of resources to offspring as a function of litter size.

scholarly journals Is diversification in male reproductive traits driven by evolutionary trade-offs between weapons and nuptial gifts?

2015 ◽  
Vol 282 (1807) ◽  
pp. 20150247 ◽  
Author(s):  
Xingyue Liu ◽  
Fumio Hayashi ◽  
Laura C. Lavine ◽  
Ding Yang
Keyword(s):  
Reproductive Traits ◽  
Accessory Gland ◽  
Mating Strategies ◽  
Male Mating ◽  
Nuptial Gift ◽  
Nuptial Gifts ◽  
Trade Off ◽  
Sexually Selected Traits ◽  
Trade Offs ◽  
Male Mating Strategies

Many male animals have evolved exaggerated traits that they use in combat with rival males to gain access to females and secure their reproductive success. But some male animals invest in nuptial gifts that gains them access to females. Both these reproductive strategies are costly in that resources are needed to produce the weapon or nuptial gift. In closely related species where both weapons and nuptial gifts are present, little is known about the potential evolutionary trade-off faced by males that have these traits. In this study, we use dobsonflies (order Megaloptera, family Corydalidae, subfamily Corydalinae) to examine the presence and absence of enlarged male weapons versus nuptial gifts within and among species. Many dobsonfly species are sexually dimorphic, and males possess extremely enlarged mandibles that they use in battles, whereas in other species, males produce large nuptial gifts that increase female fecundity. In our study, we show that male accessory gland size strongly correlates with nuptial gift size and that when male weapons are large, nuptial gifts are small and vice versa. We mapped weapons and nuptial gifts onto a phylogeny we constructed of 57 species of dobsonflies. Our among-species comparison shows that large nuptial gift production evolved in many species of dobsonfly but is absent from those with exaggerated weapons. This pattern supports the potential explanation that the trade-off in resource allocation between weapons and nuptial gifts is important in driving the diversity of male mating strategies seen in the dobsonflies, whereas reduced male–male competition in the species producing large spermatophores could be an alternative explanation on their loss of male weapons. Our results shed new light on the evolutionary interplay of multiple sexually selected traits in animals.

Dual Goals for Speed and Accuracy on the Same Performance Task

2012 ◽  
Vol 11 (3) ◽  
pp. 118-126 ◽  
Author(s):  
Olive Emil Wetter ◽  
Jürgen Wegge ◽  
Klaus Jonas ◽  
Klaus-Helmut Schmidt
Keyword(s):  
Memory Scanning ◽  
Performance Task ◽  
Performance Tasks ◽  
Trade Off ◽  
Test Experiment ◽  
Trade Offs ◽  
New Finding ◽  
Sternberg Paradigm ◽  
Speed Accuracy ◽  
Speed And Accuracy

In most work contexts, several performance goals coexist, and conflicts between them and trade-offs can occur. Our paper is the first to contrast a dual goal for speed and accuracy with a single goal for speed on the same task. The Sternberg paradigm (Experiment 1, n = 57) and the d2 test (Experiment 2, n = 19) were used as performance tasks. Speed measures and errors revealed in both experiments that dual as well as single goals increase performance by enhancing memory scanning. However, the single speed goal triggered a speed-accuracy trade-off, favoring speed over accuracy, whereas this was not the case with the dual goal. In difficult trials, dual goals slowed down scanning processes again so that errors could be prevented. This new finding is particularly relevant for security domains, where both aspects have to be managed simultaneously.

The Effects of Decision Time on Perceptions of Decisions and Decision Makers in (Moral) Trade-Off Scenarios

2019 ◽  
Author(s):  
Anna Katharina Spälti ◽  
Mark John Brandt ◽  
Marcel Zeelenberg
Keyword(s):  
Decision Process ◽  
Decision Time ◽  
Decision Makers ◽  
Process Information ◽  
Total N ◽  
Trade Off ◽  
Financial Gain ◽  
Trade Offs ◽  
Sacred Values ◽  
Moral Context

People often have to make trade-offs. We study three types of trade-offs: 1) "secular trade-offs" where no moral or sacred values are at stake, 2) "taboo trade-offs" where sacred values are pitted against financial gain, and 3) "tragic trade-offs" where sacred values are pitted against other sacred values. Previous research (Critcher et al., 2011; Tetlock et al., 2000) demonstrated that tragic and taboo trade-offs are not only evaluated by their outcomes, but are also evaluated based on the time it took to make the choice. We investigate two outstanding questions: 1) whether the effect of decision time differs for evaluations of decisions compared to decision makers and 2) whether moral contexts are unique in their ability to influence character evaluations through decision process information. In two experiments (total N = 1434) we find that decision time affects character evaluations, but not evaluations of the decision itself. There were no significant differences between tragic trade-offs and secular trade-offs, suggesting that the decisions structure may be more important in evaluations than moral context. Additionally, the magnitude of the effect of decision time shows us that decision time, may be of less practical use than expected. We thus urge, to take a closer examination of the processes underlying decision time and its perception.

Predicting Undesired Treatment Outcome in Mental Healthcare: Machine Learning Study (Preprint)

2019 ◽  
Author(s):  
Kasper Van Mens ◽  
Joran Lokkerbol ◽  
Richard Janssen ◽  
Robert de Lange ◽  
Bea Tiemens
Keyword(s):  
Machine Learning ◽  
Treatment Outcome ◽  
Mental Health Treatment ◽  
Mental Healthcare ◽  
Machine Learning Algorithms ◽  
Gradient Boosting ◽  
Trade Off ◽  
Trade Offs ◽  
Outcome Monitoring ◽  
Extreme Gradient Boosting

BACKGROUND It remains a challenge to predict which treatment will work for which patient in mental healthcare. OBJECTIVE In this study we compare machine algorithms to predict during treatment which patients will not benefit from brief mental health treatment and present trade-offs that must be considered before an algorithm can be used in clinical practice. METHODS Using an anonymized dataset containing routine outcome monitoring data from a mental healthcare organization in the Netherlands (n = 2,655), we applied three machine learning algorithms to predict treatment outcome. The algorithms were internally validated with cross-validation on a training sample (n = 1,860) and externally validated on an unseen test sample (n = 795). RESULTS The performance of the three algorithms did not significantly differ on the test set. With a default classification cut-off at 0.5 predicted probability, the extreme gradient boosting algorithm showed the highest positive predictive value (ppv) of 0.71(0.61 – 0.77) with a sensitivity of 0.35 (0.29 – 0.41) and area under the curve of 0.78. A trade-off can be made between ppv and sensitivity by choosing different cut-off probabilities. With a cut-off at 0.63, the ppv increased to 0.87 and the sensitivity dropped to 0.17. With a cut-off of at 0.38, the ppv decreased to 0.61 and the sensitivity increased to 0.57. CONCLUSIONS Machine learning can be used to predict treatment outcomes based on routine monitoring data.This allows practitioners to choose their own trade-off between being selective and more certain versus inclusive and less certain.

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