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 Early-life reproduction is associated with increased mortality risk but enhanced lifetime fitness in pre-industrial humans

2015 ◽  
Vol 282 (1804) ◽  
pp. 20143053 ◽  
Author(s):  
Adam D. Hayward ◽  
Ilona Nenko ◽  
Virpi Lummaa
Keyword(s):  
Reproductive Success ◽  
Evolutionary Theory ◽  
Mortality Risk ◽  
Early Life ◽  
Later Life ◽  
Lifetime Reproductive Success ◽  
Reproductive Senescence ◽  
Trade Offs ◽  
Investment In Reproduction ◽  
Using Data

The physiology of reproductive senescence in women is well understood, but the drivers of variation in senescence rates are less so. Evolutionary theory predicts that early-life investment in reproduction should be favoured by selection at the cost of reduced survival and faster reproductive senescence. We tested this hypothesis using data collected from preindustrial Finnish church records. Reproductive success increased up to age 25 and was relatively stable until a decline from age 41. Women with higher early-life fecundity (ELF; producing more children before age 25) subsequently had higher mortality risk, but high ELF was not associated with accelerated senescence in annual breeding success. However, women with higher ELF experienced faster senescence in offspring survival. Despite these apparent costs, ELF was under positive selection: individuals with higher ELF had higher lifetime reproductive success. These results are consistent with previous observations in both humans and wild vertebrates that more births and earlier onset of reproduction are associated with reduced survival, and with evolutionary theory predicting trade-offs between early reproduction and later-life survival. The results are particularly significant given recent increases in maternal ages in many societies and the potential consequences for offspring health and fitness.

Games Embedded in Life

2020 ◽  
pp. 203-230
Author(s):  
John M. McNamara ◽  
Olof Leimar
Keyword(s):  
Reproductive Success ◽  
Dynamic Games ◽  
Traditional Approach ◽  
Holistic Approach ◽  
Current Situation ◽  
Lifetime Reproductive Success ◽  
Trade Off ◽  
State Dependent ◽  
Mean Lifetime ◽  
Payoff Structure

Many games focus on a part of the life of an organism. The payoff structure of the game then represents how the game affects fitness proxies such as mean lifetime reproductive success, which are concerned with the whole of the life of the organism. However, the traditional approach of specifying payoffs in advance of the analysis of the game can lead to inconsistencies because the rest of the life of an individual is not fixed but depends on what happens in the game. This chapter concerns this issue, identifying situations in which a more holistic approach is needed. A series of models illustrates links between the current situation and a lifetime perspective. When each of two parents must decide whether to care for their common young or desert, the payoff for desertion depends on the solution of the game and cannot be specified in advance. A game in which two males contest for a female illustrates the approach that must be taken if this game can be repeated at a later time. A game in which individuals must possess territories in order to breed is developed that highlights various interdependencies and, by incorporating learning, advances the understanding of owner–intruder interactions. The interdependencies in state-dependent dynamic games are also illustrated with a model in which individuals must trade off the risks of starvation and predation in a situation in which the choice of the best foraging habitat depends on the number of other animals that use that habitat.

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 Heterotrophic eukaryotes show a slow-fast continuum, not a gleaner–exploiter trade-off

2020 ◽  
Vol 117 (40) ◽  
pp. 24893-24899
Author(s):  
Thomas Kiørboe ◽  
Mridul K. Thomas
Keyword(s):  
Positive Relationship ◽  
Ingestion Rate ◽  
Negative Relationship ◽  
Large Mammals ◽  
Ecological Processes ◽  
Trade Off ◽  
Trade Offs ◽  
Wide Range ◽  
Fast Gradient ◽  
Using Data

Gleaners and exploiters (opportunists) are organisms adapted to feeding in nutritionally poor and rich environments, respectively. A trade-off between these two strategies—a negative relationship between the rate at which organisms can acquire food and ingest it—is a critical assumption in many ecological models. Here, we evaluate evidence for this trade-off across a wide range of heterotrophic eukaryotes from unicellular nanoflagellates to large mammals belonging to both aquatic and terrestrial realms. Using data on the resource acquisition and ingestion rates in >500 species, we find no evidence of a trade-off across species. Instead, there is a positive relationship between maximum clearance rate and maximum ingestion rate. The positive relationship is not a result of lumping together diverse taxa; it holds within all subgroups of organisms we examined as well. Correcting for differences in body mass weakens but does not reverse the positive relationship, so this is not an artifact of size scaling either. Instead, this positive relationship represents a slow–fast gradient in the “pace of life” that overrides the expected gleaner–exploiter trade-off. Other trade-offs must therefore shape ecological processes, and investigating them may provide deeper insights into coexistence, competitive dynamics, and biodiversity patterns in nature. A plausible target for study is the well-documented trade-off between growth rate and predation avoidance, which can also drive the slow–fast gradient we observe here.

scholarly journals Life history variation is maintained by fitness trade-offs and negative frequency-dependent selection

2018 ◽  
Vol 115 (17) ◽  
pp. 4441-4446 ◽  
Author(s):  
Mark R. Christie ◽  
Gordon G. McNickle ◽  
Rod A. French ◽  
Michael S. Blouin
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Life History Strategies ◽  
Lifetime Reproductive Success ◽  
Life History Variation ◽  
Additional Energy ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Trade Offs ◽  
Negative Frequency Dependent Selection

The maintenance of diverse life history strategies within and among species remains a fundamental question in ecology and evolutionary biology. By using a near-complete 16-year pedigree of 12,579 winter-run steelhead (Oncorhynchus mykiss) from the Hood River, Oregon, we examined the continued maintenance of two life history traits: the number of lifetime spawning events (semelparous vs. iteroparous) and age at first spawning (2–5 years). We found that repeat-spawning fish had more than 2.5 times the lifetime reproductive success of single-spawning fish. However, first-time repeat-spawning fish had significantly lower reproductive success than single-spawning fish of the same age, suggesting that repeat-spawning fish forego early reproduction to devote additional energy to continued survival. For single-spawning fish, we also found evidence for a fitness trade-off for age at spawning: older, larger males had higher reproductive success than younger, smaller males. For females, in contrast, we found that 3-year-old fish had the highest mean lifetime reproductive success despite the observation that 4- and 5-year-old fish were both longer and heavier. This phenomenon was explained by negative frequency-dependent selection: as 4- and 5-year-old fish decreased in frequency on the spawning grounds, their lifetime reproductive success became greater than that of the 3-year-old fish. Using a combination of mathematical and individual-based models parameterized with our empirical estimates, we demonstrate that both fitness trade-offs and negative frequency-dependent selection observed in the empirical data can theoretically maintain the diverse life history strategies found in this population.

scholarly journals Revealing mechanisms underlying variation in malaria virulence: effective propagation and host control of uninfected red blood cell supply

2012 ◽  
Vol 9 (76) ◽  
pp. 2804-2813 ◽  
Author(s):  
C. J. E. Metcalf ◽  
G. H. Long ◽  
N. Mideo ◽  
J. D. Forester ◽  
O. N. Bjørnstad ◽  
...  
Keyword(s):  
Blood Cell ◽  
Statistical Methods ◽  
Red Blood Cell ◽  
Malaria Parasite ◽  
Trade Off ◽  
Transmission Rates ◽  
Fitness Consequences ◽  
Self Harm ◽  
Using Data ◽  
Self Defence

Malaria parasite clones with the highest transmission rates to mosquitoes also tend to induce the most severe fitness consequences (or virulence) in mammals. This is in accord with expectations from the virulence–transmission trade-off hypothesis. However, the mechanisms underlying how different clones cause virulence are not well understood. Here, using data from eight murine malaria clones, we apply recently developed statistical methods to infer differences in clone characteristics, including induction of differing host-mediated changes in red blood cell (RBC) supply. Our results indicate that the within-host mechanisms underlying similar levels of virulence are variable and that killing of uninfected RBCs by immune effectors and/or retention of RBCs in the spleen may ultimately reduce virulence. Furthermore, the correlation between clone virulence and the degree of host-induced mortality of uninfected RBCs indicates that hosts increasingly restrict their RBC supply with increasing intrinsic virulence of the clone with which they are infected. Our results demonstrate a role for self-harm in self-defence for hosts and highlight the diversity and modes of virulence of malaria.

scholarly journals Attentive red squirrel mothers have faster-growing pups and higher lifetime reproductive success

2019 ◽  
Author(s):  
Sarah E Westrick ◽  
Ryan W Taylor ◽  
Stan Boutin ◽  
Jeffrey E Lane ◽  
Andrew G McAdam ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Individual Variation ◽  
Maternal Care ◽  
Wild Population ◽  
Lifetime Reproductive Success ◽  
Red Squirrels ◽  
Trade Off ◽  
Offspring Growth ◽  
North American Red Squirrels ◽  
Care Behavior

AbstractParental investment theory predicts that observed levels of parental care afforded to offspring are set by the benefits (to offspring quality and survival) relative to the costs (to parental survival or future reproduction). Although difficult to document in mammals, there is often substantial individual-variation in the amount of parental care within species. We measured the impact of individual variation in maternal care (“attentiveness” towards offspring or maternal motivation) on offspring growth and survival in a wild population of North American red squirrels (Tamiasciurus hudsonicus). We used latency to return to pups following a nest intrusion as a measure of maternal attentiveness to pups. We found this behavior to be repeatable within individuals suggesting this behavior is a personality trait or a “maternal style”. In this population, postnatal growth rate is important for pup overwinter survival. Pups from large litters grew faster if they had a highly attentive mother, indicating that maternal care behavior can mitigate the trade-off between litter size and offspring growth and potentially improve survival of pups. Additionally, more attentive mothers had slightly higher lifetime reproductive success than less attentive mothers. These results highlight important fitness effects of having a highly attentive mother and show that maternal care behavior can alter a fundamental life history trade-off between offspring quantity and quality.Lay SummaryIt pays to be attentive to your pups as a squirrel mom. In a long-term study of a wild population of North American red squirrels, we observed repeatable individual variation in maternal attentiveness towards offspring. Mothers who returned faster to pups following a nest intrusion produced faster growing pups and were able to produce larger fast-growing litters. Over their entire lifetime, attentive mothers also had more offspring recruit into the breeding population.

scholarly journals THEWEIGHT: A simple and flexible algorithm for simulating non-ideal, age-structured populations

2022 ◽  
Author(s):  
Robin S Waples
Keyword(s):  
Reproductive Success ◽  
Evolutionary Biology ◽  
Simulation Models ◽  
Worked Examples ◽  
Structured Populations ◽  
Lifetime Reproductive Success ◽  
Fisher Model ◽  
Real Value ◽  
Age Structured ◽  
Basic Features

1. The Wright-Fisher model, which directs how matings occur and how genes are transmitted across generations, has long been a lynchpin of evolutionary biology. This model is elegantly simple, analytically tractable, and easy to implement, but it has one serious limitation: essentially no real species satisfies its many assumptions. With growing awareness of the importance of jointly considering both ecology and evolution in eco-evolutionary models, this limitation has become more apparent, causing many researchers to search for more realistic simulation models. 2. A recently described variation retains most of the Wright-Fisher simplicity but provides greater flexibility to accommodate departures from model assumptions. This generalized Wright-Fisher model relaxes the assumption that all individuals have identical expected reproductive success by introducing a vector of parental weights w that specifies relative probabilities different individuals have of producing offspring. With parental weights specified this way, expectations of key demographic parameters are simple functions of w. This allows researchers to quantitatively predict the consequences of non-Wright-Fisher features incorporated into their models. 3. An important limitation of the Wright-Fisher model is that it assumes discrete generations, whereas most real species are age-structured. Here I show how an algorithm (THEWEIGHT) that implements the generalized Wright-Fisher model can be used to model evolution in age-structured populations with overlapping generations. Worked examples illustrate simulation of seasonal and lifetime reproductive success and show how the user can pick vectors of weights expected to produce a desired level of reproductive skew or a desired Ne/N ratio. Alternatively, weights can be associated with heritable traits to provide a simple, quantitative way to model natural selection. Using THEWEIGHT, it is easy to generate positive or negative correlations of individual reproductive success over time, thus allowing explicit modeling of common biological processes like skip breeding and persistent individual differences. 4. R code is provided to implement basic features of THEWEIGHT and applications described here. However, required coding changes to the Wright-Fisher model are modest, so the real value of the new algorithm is to encourage users to adopt its features into their own or others models.

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