scholarly journals Individual-specific mortality is associated with how individuals evaluate future discounting decisions

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180304 ◽  
Author(s):  
Anthony J. Lee ◽  
Lisa M. DeBruine ◽  
Benedict C. Jones
Keyword(s):  
Life History ◽  
Life Expectancy ◽  
Intertemporal Choice ◽  
Theoretical Models ◽  
Delay Period ◽  
Central Component ◽  
Relative Gain ◽  
Future Reward ◽  
Trade Offs ◽  
Future Discounting

How organisms discount the value of future rewards is associated with many important outcomes, and may be a central component of theories of life-history. According to life-history theories, prioritizing immediacy is indicative of an accelerated strategy (i.e. reaching reproductive maturity quickly and producing many offspring at the cost of long-term investment). Previous work extrapolating life-history theories to facultative calibration of life-history traits within individuals has theorized that cues to mortality can trigger an accelerated strategy; however, compelling evidence for this hypothesis in modern humans is lacking. We assessed whether country-level life expectancy predicts individual future discounting behaviour across multiple intertemporal choice items in a sample of 13 429 participants from 54 countries. Individuals in countries with lower life expectancy were more likely to prefer an immediate reward to one that is delayed. Individuals from countries with greater life expectancy were especially more willing to wait for a future reward when the relative gain in choosing the future reward was large and/or the delay period was short. These results suggest that cues to mortality can influence the way individuals evaluate intertemporal decisions, which in turn can inform life-history trade-offs. We also found that older (but not very old) participants were more willing to wait for a future reward when there is a greater relative gain and/or shorter delay period, consistent with theoretical models that suggest individuals are more future-orientated at middle age.

scholarly journals Individual-specific mortality is associated with how individuals evaluate future discounting decisions

2018 ◽  
Author(s):  
Anthony J Lee ◽  
Lisa Marie DeBruine ◽  
Benedict C Jones
Keyword(s):  
Life History ◽  
Life Expectancy ◽  
Intertemporal Choice ◽  
Theoretical Models ◽  
Delay Period ◽  
Central Component ◽  
Relative Gain ◽  
Future Reward ◽  
Trade Offs ◽  
Future Discounting

How organisms discount the value of future rewards is associated with many important outcomes, and may be a central component of theories of life-history. According to life-history theories, prioritising immediacy is indicative of an accelerated strategy (i.e., reaching reproductive maturity quickly and producing many offspring at the cost of long-term investment). Previous work extrapolating life-history theories to facultative calibration of life-history traits within individuals has theorised that cues to mortality can trigger an accelerated strategy; however, compelling evidence for this hypothesis in modern humans is lacking. We assessed whether country-level life expectancy predicts individual future discounting behaviour across multiple intertemporal choice items in a sample of 13,429 participants from 54 countries. Individuals in countries with lower life expectancy were more likely to prefer an immediate reward to one that is delayed. Individuals from countries with greater life expectancy were especially more willing to wait for a future reward when the relative gain in choosing the future reward was large and/or the delay period was short. These results suggest that cues to mortality can influence the way individuals evaluate intertemporal decisions, which in turn can inform life-history trade-offs. We also found that older (but not very old) participants were more willing to wait for a future reward when there is a greater relative gain and/or shorter delay period, consistent with theoretical models that suggest individuals are more future-orientated at middle age.

scholarly journals Life-history theory, chronic childhood illness and the timing of first reproduction in a British birth cohort

2012 ◽  
Vol 279 (1740) ◽  
pp. 2998-3002 ◽  
Author(s):  
David Waynforth
Keyword(s):  
Life History ◽  
Chronic Disease ◽  
Life Expectancy ◽  
Life History Theory ◽  
Pubertal Development ◽  
Experimental Studies ◽  
Past Research ◽  
Theoretical Models ◽  
Age At First Reproduction ◽  
First Reproduction

Life-history theoretical models show that a typical evolutionarily optimal response of a juvenile organism to high mortality risk is to reach reproductive maturity earlier. Experimental studies in a range of species suggest the existence of adaptive flexibility in reproductive scheduling to maximize fitness just as life-history theory predicts. In humans, supportive evidence has come from studies comparing neighbourhoods with different mortality rates, historical and cross-cultural data. Here, the prediction is tested in a novel way in a large ( n = 9099), longitudinal sample using data comparing age at first reproduction in individuals with and without life-expectancy-reducing chronic disease diagnosed during childhood. Diseases selected for inclusion as chronic illnesses were those unlikely to be significantly affected by shifting allocation of effort away from reproduction towards survival; those which have comparatively large effects on mortality and life expectancy; and those which are not profoundly disabling. The results confirmed the prediction that chronic disease would associate with early age at first reproduction: individuals growing up with a serious chronic disease were 1.6 times more likely to have had a first child by age 30. Analysis of control variables also confirmed past research findings on links between being raised father-absent and early pubertal development and reproduction.

Semelparity and Iteroparity

2018 ◽  
pp. 98-124
Author(s):  
Øystein Varpe ◽  
Maciej J. Ejsmond
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Value Of Life ◽  
Central Component ◽  
Trade Offs ◽  
Evolutionary Changes ◽  
Optimal Resource ◽  
The Many ◽  
Rapid Drop ◽  
Adult Abundance

Diversity in reproduction schedules is a central component of life history variability, with life span and age at maturity as key traits. Closely linked is the number of reproductive attempts and if organisms reproduce only once followed by death (semelparity) or spread reproduction over multiple and separated episodes during the reproductive lifespan (iteroparity). Amphipoda and Isopoda are two crustacean groups with many semelparous species, but semelparity is also part of other groups such as Decapoda, Copepoda, and Lepostraca. We briefly review theories posited for the evolution of semelparity and iteroparity, covering models on demography in both deterministic and fluctuating environments, and examine models on optimal resource allocation. We provide predictions of these theories, a guide on how to test them in crustaceans, and illustrate how theory can help us understand the diversity within this major taxon. We also point out a few shortcomings of these theories. One is that immediate recruitment is usually assumed in studies of semelparity, which is a poor assumption for the many crustaceans that form egg banks with prolonged recruitment. Another is the lack of models where iteroparity versus semelparity emerge as a consequence of life history trade-offs, rather than the more common approach that assumes demographic parameters. Furthermore, we argue that treating semelparity and iteroparity as a dichotomy is sometimes problematic and that viewing these strategies as a continuum can be useful. We discuss life history correlates and the particularly relevant links between the semelparity-iteroparity axis and capital breeding and seasonality, parental care, and terminal molts. We also discuss some of the indirect methods used to conclude if a crustacean is semelparous or not, such as a rapid drop in adult abundance after reproduction or signs of growth or storage after reproduction. A central message in the chapter is the high value of life history theory as a guide when formulating explanations and projecting evolutionary changes in reproductive lifespan of crustaceans.

Oxytocin

2019 ◽  
pp. 315-334
Author(s):  
Nicholas M. Grebe ◽  
Steven W. Gangestad
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Theoretical Biology ◽  
Theoretical Models ◽  
Peptide Hormone ◽  
Future Research ◽  
Functional Interpretation ◽  
Trade Offs ◽  
Mammalian Peptide ◽  
Biological Foundation

Substantial excitement surrounds the mammalian peptide hormone oxytocin (OT) due to its potential to be a “hormone of love”—and more generally, a biological foundation for the diverse classes of intimate social bonds. Yet, theoretical models have struggled to absorb inconsistent, even contradictory, findings. Evolutionary theory will guide a coherent functional interpretation of the OT system. This chapter focuses on life history theory, a branch of theoretical biology that seeks to identify how natural selection shapes organisms’ efforts to optimally allocate limited resources. Endocrine hormones are important mediators of this process. A review of the psychological and physiological literature regarding OT suggests a number of possible trade-offs negotiated by oxytocinergic activity. This chapter proposes a provisional life history model in which OT is central to the regulation of important but vulnerable social relationships. It outlines implications of this model, addresses a number of caveats, and suggests directions for future research.

Experimentally increased costs of parental care are shunted to offspring in species with extended care

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Life History ◽  
Parental Care ◽  
Total Duration ◽  
Bird Species ◽  
Life History Strategy ◽  
Experimental Treatment ◽  
Cost Of Care ◽  
Adult Survival ◽  
Supporting Evidence ◽  
Trade Offs

Biparental care systems are a valuable model to examine conflict, cooperation, and coordination between unrelated individuals, as the product of the interactions between the parents influences the fitness of both individuals. A common experimental technique for testing coordinated responses to changes in the costs of parental care is to temporarily handicap one parent, inducing a higher cost of providing care. However, dissimilarity in experimental designs of these studies has hindered interspecific comparisons of the patterns of cost distribution between parents and offspring. Here we apply a comparative experimental approach by handicapping a parent at nests of five bird species using the same experimental treatment. In some species, a decrease in care by a handicapped parent was compensated by its partner, while in others the increased costs of care were shunted to the offspring. Parental responses to an increased cost of care primarily depended on the total duration of care that offspring require. However, life history pace (i.e., adult survival and fecundity) did not influence parental decisions when faced with a higher cost of caring. Our study highlights that a greater attention to intergenerational trade-offs is warranted, particularly in species with a large burden of parental care. Moreover, we demonstrate that parental care decisions may be weighed more against physiological workload constraints than against future prospects of reproduction, supporting evidence that avian species may devote comparable amounts of energy into survival, regardless of life history strategy.

The intrinsic mechanism of life history trade-offs: The mediating role of control striving

2017 ◽  
Vol 49 (6) ◽  
pp. 783 ◽  
Author(s):  
Yan WANG ◽  
Zhenchao LIN ◽  
Bowen HOU ◽  
Shijin SUN
Keyword(s):  
Life History ◽  
Mediating Role ◽  
Trade Offs ◽  
Intrinsic Mechanism ◽  
Control Striving

Hormones and Behavior

2019 ◽  
pp. 11-26
Author(s):  
Maren N. Vitousek ◽  
Laura A. Schoenle
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Traits ◽  
Developmental Plasticity ◽  
Endocrine System ◽  
Phenotypic Traits ◽  
Social Environments ◽  
Trade Offs ◽  
And Behavior

Hormones mediate the expression of life history traits—phenotypic traits that contribute to lifetime fitness (i.e., reproductive timing, growth rate, number and size of offspring). The endocrine system shapes phenotype by organizing tissues during developmental periods and by activating changes in behavior, physiology, and morphology in response to varying physical and social environments. Because hormones can simultaneously regulate many traits (hormonal pleiotropy), they are important mediators of life history trade-offs among growth, reproduction, and survival. This chapter reviews the role of hormones in shaping life histories with an emphasis on developmental plasticity and reversible flexibility in endocrine and life history traits. It also discusses the advantages of studying hormone–behavior interactions from an evolutionary perspective. Recent research in evolutionary endocrinology has provided insight into the heritability of endocrine traits, how selection on hormone systems may influence the evolution of life histories, and the role of hormonal pleiotropy in driving or constraining evolution.

scholarly journals Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments

2021 ◽  
Author(s):  
Anik Dutta ◽  
Fanny E. Hartmann ◽  
Carolina Sardinha Francisco ◽  
Bruce A. McDonald ◽  
Daniel Croll
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Stress Factors ◽  
Life History Trait ◽  
Adaptive Landscape ◽  
Heterogeneous Environments ◽  
Growth Responses ◽  
Trade Offs

AbstractThe adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen’s ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.

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