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Life historical consequences of natural selection
... In addition to the effects of 107 predation on morphological evolution, the guppy system has been key in developing and 108 testing concepts of life history evolution (Stearns 1989). It is generally assumed that natural 109 selection should favour maternal investment to produce larger numbers of offspring at a 110 relatively rapid pace in high mortality environments, compared to environments with low 111 mortality rates (Charlesworth 1994; Gadgil and Bossert 1970;Law 1979;Michod 1979). 112 Indeed, previous research shows that, compared to low-predation guppies, guppies from 113 high-predation habitats mature at an earlier age and at a smaller size, produce larger broods 114 with smaller offspring, have shorter interbrood intervals (defined as the number of days 115 between two births), and invest more into reproduction early in life (Reznick 1982(Reznick , 1989; 116 Reznick and Bryga 1996; Reznick and Endler 1982;Reznick, Rodd, and Cardenas 1996). ...
... Theory predicts that increased adult mortality due to predation causes evolutionary shifts in 242 life history traits in prey(Charlesworth 1994;Gadgil and Bossert 1970;Law 1979; Michod 243 1979). Natural selection should favor mothers to produce larger numbers of offspring at a 244 relatively rapid pace in high mortality environments, compared to environments with low 245 mortality rates. ...
Predation is accepted as a major evolutionary driver of life history and morphology. However, whether these traits evolve directly via predation or via indirect effects is largely unresolved. We used artificial selection over three generations to experimentally test the impact of adult predation on the evolution of life history and morphology in guppies (Poecilia reticulata). We found that, compared to control fish, predation-selected fish produced larger offspring and larger broods early in life. However, other life history parameters, such as interbrood interval and total number of offspring, showed no response. We also found that predation-selected for smaller and lighter females and for shorter tails and gonopodia in males, with no effect on body colouration. Our results show that while several traits evolve fast under selection on adult predation, several classic predation-dependent traits seem unaffected by predation selection. By comparing our experimental results to those from natural populations we can disentangle the contribution of direct and indirect effects on trait evolution under predation pressure.
... The observed life-history traits are an outcome of the constrained optimization of fitness (Parker and Maynard Smith, 1990;Charlesworth, 1990b;Partridge and Sibly, 1991). These constraints are both due to limitations of resource acquisition (Van Noordwijk and de Jong, 1986) and the restricted pathways of resource allocation (Gadgil and Bossert, 1970). Several studies have proposed the presence of a trade-off between maintenance/survival and reproduction (Kirkwood, 1977;Kirkwood and Holliday, 1979) and attempts have been made to outline optimal resource allocation in terms of costs of reproduction (Williams, 1966;Calow, 1977;Bell and Koufopanou, 1985;Reznick, 1985;Partridge and Harvey, 1988;Partridge and Sibly, 1991). ...
... P-value: *p < 0.05. Jong, 1986) and the restricted pathways of resource allocation (Gadgil and Bossert, 1970), leading to trade-off among traits. Most extensively studied trade-offs in organisms are between survival and reproduction. ...
Maximization of life-history traits is under constraints due to both, limitations of resource acquisition and the restricted pathways of resource allocation. Drosophila melanogaster has served as an excellent model organism to not only unravel various trade-offs among life history traits but also numerous aspects of host immune response. Drosophila larvae are semi-aquatic, live, feed and excrete inside the food source- often over-ripe fruits and vegetables that are rich in both commensal and pathogenic microbiota that can impact the larval survival. In this study, we have used six populations of D. melanogaster, three of which are selected for faster pre-adult development and extended adult longevity, and their three ancestral controls, to explore the impact of selection on the basal immune activity in the larval stage. The larvae from selected populations had nearly significantly upregulated plasmatocyte density, significantly higher percent phagocytosis, phagocytic index and higher transcript levels of Tep3, eater and NimC1. Selected populations also had significantly upregulated crystal cell number along with higher transcript of PPO2. Out of seven tested AMPs level, Drosomycin was significantly upregulated in selected populations while Drosocin was significantly higher in control populations. ROS levels were comparable in the selected and control populations. Our results strongly suggest that enhanced basal immune activity during larval stage manages the faster development and could be responsible for comparable larval survival of selected populations and control populations.
... El IGS se incrementa durante la ovogénesis reflejando el aumento del peso relativo de gónadas, mientras que las reservas de grasa acumuladas en hígado se movilizan a los ovarios y el IHS disminuye rápidamente (Costa, 2013;Domínguez-Petit et al., 2017); sin embargo, en este estudio los comportamientos de IGS e IHS son similares entre estados, lo que evidencia que en el Pterois la movilización de energía para la ovogénesis es rápida. Esto coincide con las diferencias en tamaño encontradas entre los dos sexos, ya que de la energía obtenida las hembras asignan una mayor proporción a la formación de productos gonadales (Gadgil et al., 1970) que al crecimiento somático. El pez león madura entre el primer y el segundo año de vida (Fogg et al., 2017;Bustos-Montes et al., 2020), y tiene alta tasa de mortalidad (Bustos-Montes et al., 2020), por lo que su estrategia energética debe ser suficientemente eficiente como para mantener tasas reproductivas altas y constantes, que compensen el gasto reduciendo su crecimiento con la maduración (Fogg et al., 2019), al igual que se ha comprobado en otros teleósteos (Reznick, 1983;Roff, 1983). ...
... A Gabriel Navas Suárez y Adriana Bermúdez Tobón por su apoyo en los laboratorios de la Universidad de Cartagena. Christian This coincides with the differences in size found between the two sexes because females allocate a greater proportion of the obtained energy to the formation of gonad products (Gadgil et al., 1970) than to the somatic growth. Lionfish mature between the first and the second year of life (Fogg et al., 2017;Bustos-Montes et al., 2020) and has a high mortality rate (Bustos-Montes et al., 2020), so its energetic strategy must be efficient enough to maintain high and constant reproductive rates that compensate the expense reducing their growth with maturing (Fogg et al., 2019), as it has been confirmed in other teleosteans (Reznick, 1983;Roff, 1983). ...
Lionfish was studied in the mesophotic environment. 237 specimens were observed, most in the upper mesophotic zone. Males were larger than females and differences between sexes in growth models were found. Sixteen prey items were identified, the most important being the teleost families Acanthuridae and Monacanthidae, and the crustacean Penaeidae. The mean of δ13C was -17.08 ± 0.36 ‰ and δ15N was 8.68 ± 0.46 ‰, with no differences between sexes. Lionfish occupies a less extensive isotopic niche in mesophotic environment than in shallow sectors; there is an isotopic niche overlap between sexes. Likewise, lionfish has specialized trophic habits. All specimens were mature and in females regression phase predominated. In females, condition factor (CF), gonadosomatic index (GSI) and hepatosomatic index (HSI) increased with gonadal development, reaching peak in the active spawning phase, and decreasing in regression. Males had a condition factor similar to spawning females, but IGS and IHS were lower
... org/ 10. 1007/ s10452-024-10126-1. for survival, growth and reproduction (Gadgil and Bossert 1970). In seasonal and annually fluctuating environments, organisms have developed several strategies for energy acquisition and allocation (Stearns 1989). ...
Energy acquisition and allocation between the somatic compartments are essential for the ecological success of an organism. The seasonal pattern of energy allocation among the different organs was evaluated in the snail Zidona dufresnei. The somatic indexes, energy density and energy content of the gonads, digestive gland, foot, and secondary sexual glands of Z. dusfresnei. The lowest foot index (FI), energy density and energy content were found in winter. The high digestive gland index (DI) and energy content (ECDIG) observed in spring likely coincide with the peak of productivity. The male’s gonads did not show seasonal energetic variation, although the gonadosomatic index (GI) of males was lower in summer than in other months. The mass and energy content of the albumen and capsule glands exhibited a decreasing pattern from spring to winter. The foot is suggested as the main energy reservoir in Z. dufresnei, the digestive gland as an energy reservoir that contributes to the gonadal maturation, whereas the energy of the capsule and the albumen glands contributes to the spawning. This study highlights seasonal variations in the energy content of the foot (edible compartment) and the significance of secondary sexual glands in understanding the bioenergetics of Z. dusfresnei and offspring fitness. These findings should be taken into consideration in fisheries management decisions for this ecologically and commercially important species.
... The entire suite of LH trade-offs can best be conceptualized as a single basic fitness trade-off between present and future reproduction (Bell and Koufopanou, 1986;Harshman and Zera, 2007). This trade-off implies that higher survival or higher fertility (for self or offspring) can only be achieved at the expense of the other (Gadgil and Bossert, 1970). Higher vital rates at one point in time come at the expense of lower rates at another point in time; or increased fitness of ego comes at the expense of decreased fitness of offspring and other close kin. ...
Human evolutionary demography is an emerging field blending natural science with social science. This edited volume provides a much-needed, interdisciplinary introduction to the field and highlights cutting-edge research for interested readers and researchers in demography, the evolutionary behavioural sciences, biology, and related disciplines.
By bridging the boundaries between social and biological sciences, the volume stresses the importance of a unified understanding of both in order to grasp past and current demographic patterns. Demographic traits, and traits related to demographic outcomes, including fertility and mortality rates, marriage, parental care, menopause, and cooperative behavior are subject to evolutionary processes. Bringing an understanding of evolution into demography therefore incorporates valuable insights into this field; just as knowledge of demography is key to understanding evolutionary processes. By asking questions about old patterns from a new perspective, the volume—composed of contributions from established and early-career academics—demonstrates that a combination of social science research and evolutionary theory offers holistic understandings and approaches that benefit both fields.
Human Evolutionary Demography introduces an emerging field in an accessible style. It is suitable for graduate courses in demography, as well as upper-level undergraduates. Its range of research is sure to be of interest to academics working on demographic topics (anthropologists, sociologists, demographers), natural scientists working on evolutionary processes, and disciplines which cross-cut natural and social science, such as evolutionary psychology, human behavioral ecology, cultural evolution, and evolutionary medicine. As an accessible introduction, it should interest readers whether or not they are currently familiar with human evolutionary demography.
... However, a more developed metabolic machinery also entails higher costs spent on self-maintenance, and finite energy, when allocated into one function, can limit other processes (Stearns, 1992). Hence, the 'allocation' hypothesis considers metabolic machinery costly and expects negative fitness-related consequences (Careau et al., 2014;Gadgil & Bossert, 1970;Larivee et al., 2010;Steyermark, 2002). In endothermic animals characterized by the ability to produce heat as a byproduct of energy metabolism, the self-maintenance costs of metabolic machinery correlate with the basal metabolic rate (BMR)the minimum metabolism required for a resting animal to maintain a stable and high body temperature (T b ) under thermoneutral conditions (McNab, 1997;Scholander et al., 1950). ...
Maintenance metabolism as the minimum energy expenditure needed to maintain homeothermy (a high and stable body temperature, Tb), reflects the magnitude of metabolic machinery and the associated costs of self‐maintenance in endotherms (organisms able to produce heat endogenously). Therefore, it can interact with most, if not all, organismal functions, including the behavior–fitness linkage. Many endothermic animals can avoid the costs of maintaining homeothermy and temporally reduce Tb and metabolism by entering heterothermic states like torpor, the most effective energy‐saving strategy. Variations in BMR, behavior, and torpor use are considered to be shaped by food resources, but those conclusions are based on research studying these traits in isolation. We tested the effect of ecological contexts (food availability and predation risk) on the interplay between the maintenance costs of homeothermy, heterothermy, and exploration in a wild mammal—the yellow‐necked mouse. We measured maintenance metabolism as basal metabolic rate (BMR) using respirometry, distance moved (exploration) in the open‐field test, and variation in Tb (heterothermy) during short‐term fasting in animals captured at different locations of known natural food availability and predator presence, and with or without supplementary food resources. We found that in winter, heterothermy and exploration (but not BMR) negatively correlated with natural food availability (determined in autumn). Supplementary feeding increased mouse density, predation risk and finally had a positive effect on heterothermy (but not on BMR or exploration). The path analysis testing plausible causal relationships between the studied traits indicated that elevated predation risk increased heterothermy, which in turn negatively affected exploration, which positively correlated with BMR. Our study indicates that adaptive heterothermy is a compensation strategy for balancing the energy budget in endothermic animals experiencing low natural food availability. This study also suggests that under environmental challenges like increased predation risk, the use of an effective energy‐saving strategy predicts behavioral expression better than self‐maintenance costs under homeothermy.
... (iii) Alternative method of calculating optimal control In the present study, Pontryagin's maximum principle was adopted for analysis. Dynamic programming is an alternative method of solving the dynamic optimization problem 48,49 , which has been used in the evolutionary ecology to analyze the optimal life history schedule of plants and animals 39,[50][51][52] . Since dynamic programming easily extends to situations including discrete-time dynamics and stochastic environments, developing corresponding analyses based on the dynamic programming method may provide us with a different perspective on the problem. ...
The leaves of many trees emit volatile organic compounds (abbreviated as BVOCs), which protect them from various damages, such as herbivory, pathogens, and heat stress. For example, isoprene is highly volatile and is known to enhance the resistance to heat stress. In this study, we analyze the optimal seasonal schedule for producing isoprene in leaves to mitigate damage. We assume that photosynthetic rate, heat stress, and the stress-suppressing effect of isoprene may vary throughout the season. We seek the seasonal schedule of isoprene production that maximizes the total net photosynthesis using Pontryagin’s maximum principle. The isoprene production rate is determined by the changing balance between the cost and benefit of enhanced leaf protection over time. If heat stress peaks in midsummer, isoprene production can reach its highest levels during the summer. However, if a large portion of leaves is lost due to heat stress in a short period, the optimal schedule involves peaking isoprene production after the peak of heat stress. Both high photosynthetic rate and high isoprene volatility in midsummer make the peak of isoprene production in spring. These results can be clearly understood by distinguishing immediate impacts and the impacts of future expectations.
... Extrinsic factors such as weather events, fluctuating resources, and anthropogenic changes can affect reproductive timing and viability, and different species are known to utilize different strategies in response (James & Shine, 1985). Similarly, intrinsic factors such as functional constraints that arise from limited resources (e.g., energy, nutrients, time) allocated among competing, internal demands (Gadgil & Bossert, 1970) affect reproductive success. Immediate reproductive investment is therefore determined by the costs that can be afforded with respect to other key fitness traits (Roff et al., 2006). ...
Reproduction, although absolutely essential to a species’ persistence, is in itself challenging. As anthropogenic change increasingly affects every landscape on Earth, it is critical to understand how specific pressures impact the reproductive efforts of individuals, which directly contribute to the success or failure of populations. However, organisms rarely encounter a single burden at a time, and the interactions of environmental challenges can have compounding effects. Understanding environmental and physiological pressures is difficult because they are often context‐dependent and not generalizable, but long‐term monitoring across variable landscapes and weather patterns can improve our understanding of these complex interactions. We tested the effects of urbanization, climate, and individual condition on the reproductive investment of wild side‐blotched lizards (Uta stansburiana) by measuring physiological/reproductive metrics from six populations in urban and rural areas over six consecutive years of variable precipitation. We observed that reproductive stage affected body condition, corticosterone concentration, and oxidative stress. We also observed that reproductive patterns differed between urban and rural populations depending on rainfall, with rural animals increasing reproductive investment during rainier years compared to urban conspecifics, and that reproductive decisions appeared to occur early in the reproductive process. These results demonstrate the plastic nature of a generalist species optimizing lifetime fitness under varying conditions.
... The copyright holder for this preprint (which this version posted April 13, 2024. ; https://doi.org/10.1101/2024.04.11.588938 doi: bioRxiv preprint invariant parameters for survival and growth, but life histories often have varying investment 663 in growth, survival, and reproduction over the course of the life cycle (Gadgil & Bossert (1970), Jones et al. (2014)). We intentionally modeled populations with simple demography, isolating effects of longevity while removing other life-history features (such as life stages buffered from 666 selection) that are not necessary for longevity, even if they sometimes appear in the life histories of long-lived organisms. ...
Evolutionary rescue” is the process by which a population experiencing severe environmental change avoids extinction through adaptation. Theory predicts when rescue is favored, but currently relies on assumptions of non-overlapping generations and therefore annual, semelparous life cycles. It has been hypothesized that longevity and iteroparity impede rescue by slowing rates of adaptation, although this hypothesis has rarely been tested. We develop a model with longevity determined by the balance of survival and reproduction and selection acting on survival through a quantitative trait. We analytically characterize the demography and evolution of cohorts, demonstrating that longevity allows repeated selection over the lifetime, with the surprising finding that this can decouple mean genotype and phenotype within a cohort. We then simulate populations at three longevities responding to environmental change. Under perfect trait heritability, longevity produces negligible differences in adaptation rates, but under low heritability, high-longevity populations experience a transient phase of rapid phenotypic change accompanied by slower genotypic change. More importantly, longevity is associated with slower intrinsic population growth rates regardless of trait heritability, ultimately hindering rescue. We connect these results to prior demographic and evolutionary theory and recent efforts to incorporate longevity into models of adaptation.
... Resources available to an organism are limited and must be allocated to different major but competing processes, such as growth and reproduction (Cody 1966;Williams 1966;Stearns 1992;Reich 2014), which incur physiological and demographic costs (Bazzaz & Grace 1997;Euler et al. 2012;Sletvold &Ågren 2015). Internal conflicts in resource allocation lead to trade-offs that can influence fitness and evolution of specific life-history traits (Gadgil & Bossert 1970;McGraw & Garbutt 1990;Blumstein et al. 2022). Iteroparous plants are capable of reproducing multiple times during their lifespan; therefore, they must be flexible in their allocation of resources to growth versus reproduction (Bonser & Aarssen 1996;Bazzaz & Grace 1997;Wenk et al. 2018). ...
Resource allocation in plants is a fundamental aspect of life history theory. In Cactaceae, the specific trade‐off between sexual reproduction and vegetative growth has still not been studied. The aim of this work was to assess if there is a trade‐off between growth and reproduction, and to analyse whether both growth and allocation to reproduction depend on size of the individual.
In this study, we used Gymnocalycium monvillei , a globose cactus endemic to the mountains of central Argentina, as a model species. Specifically, we analysed the relationship of growth (percentage increase in diameter) and size of individuals (diameter) to seed production, seed mass, germination, and mean germination time. To relativize the effect of size on seed production, two variables were calculated: the ratio of seed production to plant size (RSPS), and the ratio of total seed mass to plant size (RSMS).
We found that both seed production and total seed mass were significantly related to cactus size. However, growth was not related to seed mass or to seed production, even when they were relativized. Germination and mean germination time were not related to plant size or growth.
In the studied species, a slow‐growing globose cactus, we did not find a trade‐off between growth and reproduction.
... At the same time, development at higher temperatures can lead to maturation at smaller body sizes, within and between ectothermic species (Kingsolver & Huey, 2008). Allocation to growth and reproduction determine individual body sizes, fitness, and population demographic rates (Beverton & Holt, 1959;Gadgil & Bossert, 1970;Kozłowski, 1992Kozłowski, , 1996. Yet existing theory struggles to predict how size-dependent changes in prey availability and decreases in predation risk, along with interacting effects of metabolic costs and seasonality in food availability and temperature, affect the evolution of growth (Varpe, 2017;Yanco et al., 2022). ...
Understanding how growth and reproduction will adapt to changing environmental conditions is a fundamental question in evolutionary ecology, but predicting the responses of specific taxa is challenging. Analyses of the physiological effects of climate change upon life history evolution rarely consider alternative hypothesized mechanisms, such as size‐dependent foraging and the risk of predation, simultaneously shaping optimal growth patterns. To test for interactions between these mechanisms, we embedded a state‐dependent energetic model in an ecosystem size‐spectrum to ask whether prey availability (foraging) and risk of predation experienced by individual fish can explain observed diversity in life histories of fishes. We found that asymptotic growth emerged from size‐based foraging and reproductive and mortality patterns in the context of ecosystem food web interactions. While more productive ecosystems led to larger body sizes, the effects of temperature on metabolic costs had only small effects on size. To validate our model, we ran it for abiotic scenarios corresponding to the ecological lifestyles of three tuna species, considering environments that included seasonal variation in temperature. We successfully predicted realistic patterns of growth, reproduction, and mortality of all three tuna species. We found that individuals grew larger when environmental conditions varied seasonally, and spawning was restricted to part of the year (corresponding to their migration from temperate to tropical waters). Growing larger was advantageous because foraging and spawning opportunities were seasonally constrained. This mechanism could explain the evolution of gigantism in temperate tunas. Our approach addresses variation in food availability and individual risk as well as metabolic processes and offers a promising approach to understand fish life‐history responses to changing ocean conditions.
... Organisms have a limited amount of time or energy available and therefore allocating more energy to one biological function, such as growth, will leave less energy available to allocate to other functions (Gaillard et al., 2016). Primary examples are the life history trade-off in energy allocation between growth and reproduction (Gadgil & Bossert, 1970;Reznick, 1983), and between allocating energy to current versus future reproduction (Williams, 1966a(Williams, , 1966b. Accounting for energy allocation processes at the individual organismal level is important as it allows for emergent differences in dynamics between populations or species even if they have similar traits. ...
Variation in life history traits in animals and plants can often be structured along major axes of life history strategies. The position of a species along these axes can inform on their sensitivity to environmental change. For example, species with slow life histories are found to be less sensitive in their long‐term population responses to environmental change than species with fast life histories.
This provides a tantalizing link between sets of traits and population responses to change, contained in a highly generalizable theoretical framework.
Life history strategies are assumed to reflect the outcome of life history tradeoffs that, by their very nature, act at the individual level. Examples include the tradeoff between current and future reproductive success, and allocating energy into growth versus reproduction. But the importance of such tradeoffs in structuring population‐level responses to environmental change remains understudied.
We aim to increase our understanding of the link between individual‐level life history tradeoffs and the structuring of life history strategies across species, as well as the underlying links to population responses to environmental change.
We find that the classical association between lifehistory strategies and population responses to environmental change breaks down when accounting for individual‐level tradeoffs and energy allocation.
Therefore, projecting population responses to environmental change should not be inferred based only on a limited set of species traits.
We summarize our perspective and a way forward in a conceptual framework.
... According to this theory, individuals select a reproductive strategy that maximizes adaptation (i.e., increasing the chances of survival and offspring) based on environmental influences affecting early life development (Łukasik et al., 2021). The theory posits that people's reproductive strategies depend on the specific allocation of the body's material and bioenergetic resources (Gadgil & Bossert, 1970). Moreover, these allocations include somatic efforts related to organism survival (e.g., maintaining vital functions or developing the organism, as well as the acquisition of knowledge, education, or skills in humans) and reproductive efforts associated with offspring production (Del Giudice & Belsky, 2011). ...
A life history strategy is a cohesive set of biological and psychosocial characteristics that reflect individual differences in how people adapt to their environment (Brumbach et al., 2009). Life history strategy refers to the set of reproductive and survival behaviors that organisms adopt to maximize their fitness in specific environments (Buss & Schmitt, 2019). This strategy involves the allocation of resources and energy by organ- isms to various life history traits, such as growth, reproduction, and survival. It encompasses trade-offs between these traits, where allocating more resources to one trait may come at the expense of another (Lu et al., 2022).
... other problems [14]. Authenticity makes people more sensitive to tasks that are more realistic, meaningful, and unique to their individualities, liberating them from assuming tasks that are beyond their strength. ...
This article substantiates the importance of studying personal authenticity as loyalty to one's true Self, considers historical and cultural prototypes of this phenomenon, and notes the difference between the Eastern and Western traditions of understanding the true Self: in the East, it is a person's dialog with the world, and in the West, it is inner harmony. Four basic oppositions are proposed to describe authenticity: "to have" versus "to be" (adapta-tion vs. meaning); source vs. effect vs. epiphenomenon; molecular vs. molar; internal vs. external. The main function of authenticity is identified as monitoring the meaningfulness of life lived by a person in accordance with their unique calling. The contemporary descriptive and operationalized concepts of authenticity are compared; their limitations when transferred to Russian culture are noted. The original agent-based conception of authenticity is proposed , understood as a person's loyalty to their individuality, the space-time context of their life and life-calling. The status of authenticity in this sense is the inherent human trait of sensitivity to situations. The agent conception is supported by the Moscow Authenticity Scale as the main standardized measurement tool. The resource role of authenticity in stressful situations of various kinds is discussed. Based on the impact of negative life events obtained in various fields of psychology, a hypothetical model of the possible change and genesis of authenticity under stress is substantiated.
... Individual growth rates from all turtles were used to estimate body size at the onset of sexual maturity. In previous studies of freshwater turtles, changes in growth rates have indicated the onset of sexual maturity, where growth slowed as resources were allocated to reproduction (Gadgil and Bossert 1970;Bury 1979;Georges 1985;Kennett 1996). When growth rates are plotted against carapace length at the midpoint of the growth rate interval, a segmented linear regression can be used to determine if, and at what size, a change in slope occurs indicating the onset of sexual maturity (Kennett 1996;Toms and Lesperance 2003). ...
The Central American river turtle Dermatemys mawii is a critically endangered species that has incurred substantial losses over the last several decades due to overhunting. This species is now being considered for head-starting programmes (i.e., captive breeding of turtles for wild release). However, relatively little is known about their life history characteristics, especially with respect to growth and sexual maturation. A robust knowledge of D. mawii life history traits is important in developing conservation management plans. This research is the first known study to maintain hatchlings, juveniles and adults in captivity with regular morphometric data collection. Growth rates were quantified (cm yr-1) and growth parameters were calculated (e.g., growth coefficients) to estimate body size and age at onset of sexual maturity in a group of wild-caught but captive-held and captive-bred D. mawii in Belize. Sizes at the onset of sexual maturity were inferred by segmented linear regressions that identified changes in growth rate by body size. Asymptotic sizes and growth coefficients were calculated using the Fabens method and the Wang method. Parameters from these models were then applied to a modified von Bertalanffy growth equation to estimate age at the onset of sexual maturity. Male and female D. mawii begin sexual maturation at approximately 38.0 cm and 40.0 cm straight-line carapace length, respectively. Ages associated with these sizes were estimated at 13.5-16.9 years (males) and 13.6-17.3 years (females). No previous literature on growth rates or age at maturation for wild or captive D. mawii has been reported, so these results serve as a starting point in conservation management. Given the life history trait of delayed sexual maturity (>10 years), D. mawii may be more sensitive to losses of the adult population; therefore, captive breeding and head-starting programmes may be beneficial with concomitant protection of wild, adult populations.
... A long-standing hypothesis is that the life histories of organisms are shaped by natural selection to balance the benefits and costs of maturing at a particular age or expending a particular amount of reproductive effort at a specific age (Gadgil & Bossert 1970;Law 1979;Michod 1979;Stearns 1992;Charlesworth 1994;Stearns 2000;Roff 2002). Ecological factors, such as age-or size-dependent predation risk, shift patterns of mortality across the life cycle and thereby change the balance between these costs and benefits. ...
Life histories are predicted to evolve when the age schedules of mortality shift due to top-down forces such as predation. Theory on how competitive interactions alter the life history is rare. We use an explicit consumer-resource model to show that changes in the way organisms interact with their resources and changes in the properties of those resources can alter the optimal life history of a consumer. When older/larger organisms are better competitors, delayed maturity can be favored. When older/larger individuals are better competitors but also shift their resource use with age or size, alternative life histories are possible. We further show that when two species compete for shared resources, selection tends to make the life histories of the two competitors more similar. These results, some of which are opposite to predictions from traditional theory, illustrate the importance of incorporating explicit interactions between trophic levels into models for life history evolution.
... Male rock lizards (Lacerta monticola), too, appear to trade-off mating opportunities against predation risk: following a simulated predator attack, they re-emerged more quickly from their Biological Reviews (2023) refuge when mating opportunities seemed good (Martin, Lopez & Cooper, 2003). Because both components of Equation (11) may depend on state, the same is likely to be true of the optimal policy; senescent individuals may avoid activities that require a highly functioning body to mitigate risk [i.e. for which M(u) is forbiddingly high with weakened sense organs and muscles]; or they may make a terminal reproductive investment because they have little to lose [low V (Gadgil & Bossert, 1970;but see McNamara et al., 2009)]. ...
An animal's behaviour can influence many variables, such as its energy reserves, its risk of injury or mortality, and its rate of reproduction. To identify the optimal action in a given situation, these various effects can be compared in the common currency of reproductive value. While this idea has been widely used to study trade-offs between pairs of variables, e.g. between energy gain versus survival, here we present a unified framework that makes explicit how these various trade-offs fit together. This unification covers a wide range of biological phenomena, highlighting similarities in their logical structure and helping to identify knowledge gaps. To fill one such gap, we present a new model of foraging under the risk of predation and damage accumulation. We conclude by discussing the use and limitations of state-dependent optimisation theory in predicting biological observations.
... In plant biology, monocarpy refers to what is more generally known as semelparity, i.e. an organism that reproduces once and dies (Gadgil & Bossert, 1970). Therefore, monocarpic species are plants that die following a single, often massive flowering event (Simmonds, 1980;Davies & Gan, 2012). ...
The genus Cerberiopsis endemic to New Caledonia includes three species of branched woody plants. C. candelabra is a monocarpic pioneer tree (that flowers only once before dying) emblematic of forests in the south of the main island. Monocarpy in trees is rare worldwide. This intriguing life strategy is known for fewer than thirty tree species. This study aims to compare the growth strategy of Cerberiopsis species through an architectural analysis and understand which life history traits is associated with monocarpy in Cerberiopsis candelabra. The architecture of twenty individuals of each species has been described in different ontogenical stages under various natural conditions.
Our results show that the architectural unit of all the species is based on three categories of axes: the trunk, the branches and the twigs. The construction of the three species varies mainly according to (i) the synchronism of terminal flowering within the axes of the crown, (ii) the ratio of elongation and node production between the trunk and the branches, (iii) the capacity of the twig to continue branch construction after their terminal flowering, leading to the establishment of mixed axes constructed by substitution. C. candelabra is mainly distinguished from sister species by its massive and synchronous flowering which concerns all axes categories, thus preventing the branches to continue their development from the twigs.
In most cases, all three species maintain this architectural unity throughout their lives. Nevertheless, for C. candelabra and C. neriifolia some branches acquire the characteristics of the trunk by immediate total reiteration.
Regardless to its development strategy, which may seem risky, C. candelabra is the most ubiquitous species capable of colonizing both forest and disturbed open environments. This study shows how the variation of simple architectural traits can not only generate phenotypic plasticity but also a diversity of life history strategies.
... In contrast, the energy "allocation" model that arises from the "compensatory" hypothesis predicts the opposite, namely a negative relationship between BMR and proactive behaviors (Careau et al., 2008). Here, a high BMR is disadvantageous, at least under limited energy availability and/or challenging environmental conditions, as energetic maintenance competes with investments in other costly functions (Gadgil & Bossert, 1970;Steyermark, 2002). Last but not least, the "independent" model indicates that an increased energy expenditure in activity is not related to maintenance costs, and therefore, BMR does not constrain or promote costly behaviors (Careau & Garland Jr, 2012). ...
For the last two decades, behavioral physiologists aimed to explain a plausible covari-ation between energetics and personality, predicted by the "pace-of-life syndrome" (POLS) hypothesis. However, the results of these attempts are mixed with no definitive answer as to which of the two most acknowledged models "performance" or "allocation" predicts covariation between consistent among-individual variation in metabolism and repeatable behavior (animal personality). The general conclusion is that the association between personality and energetics is rather context-dependent. Life-history, behavior, and physiology as well as its plausible covariation can be considered a part of sexual dimorphism. However, up to now, only a few studies demonstrated a sex-specific correlation between metabolism and personality. Therefore, we tested the relationships between physiological and personality traits in a single population of yellow-necked mice Apodemus flavicollis in the context of a plausible between-sexes difference in this covariation. We hypothesized that the performance model will explain proactive behavior in males and the allocation model will apply to females. Behavioral traits were determined using the latency of risk-taking and the open field tests, whereas the basal metabolic rates (BMR) was measured using indirect calorimetry. We have found a positive correlation between body mass-adjusted BMR and repeatable proactive behavior in male mice, which can support the performance model. However, the females were rather consistent mainly in avoidance of risk-taking that did not correlate with BMR, suggesting essential differences in personality between sexes. Most likely, the lack of convincing association between ener-getics and personality traits at the population level is caused by a different selection acting on the life histories of males and females. This may only result in weak support for the predictions of the POLS hypothesis when assuming that only a single model explaining the link between physiology and behavior operates in males and females. Thus, there is a need to consider the differences between sexes in behavioral studies to evaluate this hypothesis.
... In plant biology, monocarpy refers to what is more generally known as semelparity, i.e. an organism that reproduces once and dies (Gadgil & Bossert, 1970). Therefore, monocarpic species are plants that die following a single, often massive flowering event (Simmonds, 1980;Davies & Gan, 2012). ...
Plant architecture strongly influences plant growth habits, as it determines the arrangement, function and fate of meristems. How architecture could be involved in the monocarpic life history, i.e. dying after flowering, remains poorly investigated. Monocarpy is evident in some species since they are annual or because their single stem flowers apically. However, monocarpy in long-lived branched trees is rare and remains poorly understood. We aim to highlight the architectural features involved in the monocarpic strategy of Cerberiopsis candelabra, a rainforest tree endemic to New Caledonia. We conducted a comparative analysis of the genus, which comprises three species with different growth habits. Twenty plants of each species were studied at different ontogenic stages. We compared their developmental sequence and analysed their processes of growth, branching, flowering and reiteration. We identified a combination of traits that distinguish the species, and we found a syndrome of two architectural features that support the monocarpic strategy in C. candelabra: the synchronous flowering of all terminal meristems and the absence of delayed branching. Flowering in C. candelabra preferentially occurs when the complete architectural sequence is developed, but the plant never shows signs of senescence, suggesting that environmental stresses, such as wind disturbance, could be the main trigger for flowering. The architecture of C. candelabra is suggested to be the most derived in the genus.
... Por lo tanto, los resultados que se obtienen con una aproximación actualista han de ser interpretados con precaución cuando se tiene como intención reconstruir la ecología de especies extintas. 1 La historia biológica (Life History) se define como el patrón que un organismo sigue para distribuir la energía finita de la que dispone entre su desarrollo, el mantenimiento, la reproducción, criar descendencia hasta la independencia y evitar la muerte (Brown, Gillooly, Allen, Savage, & West, 2004;Charnov, 1993;Gadgil & Bossert, 1970;Smith & Tompkins, 1995). Estos rasgos (Life History Traits) son las principales características que determinan el ciclo de la vida de un individuo (Calow, 1999). ...
The life of any organism is completely dependent on energy. Energy resources procurement, consumption and allocation through biological processes are essential aspects to understand an organism’s ecology. Thus, the energetic dynamics between organisms and their environment have important adaptive implications for survival and reproduction, i.e., for fitness. Under this perspective it is possible to evaluate the consequences of some anatomical and physiological human characteristics, or the assessment of certain behaviors.
Humans allocate a relevant part of their daily energy budget to locomotion and burden transport activities. Thus, around these activities, humans develop a whole range of behaviors that can be evaluated within the Human Behavioral Ecology theoretical framework. The energy distributed to these activities is not available to other biological functions, thus it is expected that humans adopt strategies that ensure their energy balance. Among these strategies it is proposed that division of labors is essential, as well as the activation of physiological and behavioral changes that ensure both mobility and reproduction.
Thus, this Ph. D. dissertation, will evaluate, from an energetic point of view, distinct physiological states and locomotion physical activities in a sample of current adult females and males. For this purpose, the data from two experimental studies were used. Both experimental studies have been designed at Bioenergy and Motion Analysis Laboratory from National Research Center of Human Evolution (CENIEH). Anthropometry, body composition and energy expenditure data have been obtained from a total of 125 subjects.
The first objective of this study was fixed to evaluate if sexual division of load transport activities, common in recent hunter-gatherer societies, is influenced by energetic differences among sexes. The data from 21 females and 27 males were used to elaborate several indices to compare, among sexes, the increment in the cost of locomotion when several burdens are transported. The results demonstrate that both females and males, carrying the same relative loads, experience the same increment over the cost of their unloaded locomotion. Therefore, apart from obvious differences in body mass, there is no evidence of an energetic advantage favoring one sex over the other that would explain the differences in load-carriage activities observed among current foraging populations.
The second research objective was planned to evaluate if body mass affects in the same way the resting energy expenditure and the locomotion costs of pregnant and nonpregnant females. Data from 77 females (42 nonpregnant and 35 pregnant females during their last gestation trimester) were obtained. All the data and the linear regression models about the relationship between body mass and energy expenditure were compared considering the physiological state. The results show that pregnant females expend less energy, both resting and during locomotion, than nonpregnant females with a similar body mass. It is proposed that this difference is caused by pregnant females having lesser percentages of metabolically active body tissues (Fat Free Mass) and larger percentages of metabolically passive body tissues (Fat Mass).
Two main conclusions were established from the outcomes obtained. On the one hand, the division of labor, frequently reported in hunter-gatherer activities, could be explained as a behavioral adaptation that increases individual fitness and, finally, the fitness of the entire group. In this line, it is proposed that the females of these populations perform preferably certain activities, because they benefit the group while the women themselves would be improving their own survival opportunities. Meanwhile, other group members could be focused on carrying out other complementary activities that would enhance the collective foraging efficacy. Consequently, it may be possible that the ability to develop different types of cooperation (phenotypic plasticity), has a great adaptive value, and it would have been selected throughout human evolution.
On the other hand, apart from behavioral adaptations, gestation related physiological changes could cause that pregnancy may not be as energetically constraining as usually assumed, agreeing with other studies that have detected a great variability in human pregnancy costs. This evidence would provide another reason for successful human pregnancies in differing ecological conditions, even when physical activity conducts do not vary during gestation. Similarly, as other researchers have found, the evolutionary relevance of Fat Mass accretion for both human survival and reproduction is highlighted.
To finally conclude, the capability to cooperate organizing the foraging tasks, as well as the changes in body composition related to pregnancy that influence gestation energy requirements, would be essential traits to understanding human populations development from a comparative perspective.
... Therefore, the remaining seeds get a chance to germinate and thereby initiate the regeneration of forests. The third hypothesis could explain the utility of the long vegetative phase (Gadgil and Bossert, 1970). According to this theory, the extended vegetative phase is dedicated to the acquisition of sufficient resources for flowering. ...
... Therefore, the remaining seeds get a chance to germinate and thereby initiate the regeneration of forests. The third hypothesis could explain the utility of the long vegetative phase (Gadgil and Bossert, 1970). According to this theory, the extended vegetative phase is dedicated to the acquisition of sufficient resources for flowering. ...
... The third trade-off is mating vs. parenting. Both mating (finding and attracting potential mates, competing with rivals and securing copulation) and parental investment are costly in terms of energy expenditure, and compete for individual's energy budget (Gadgil, Bossert, 1970; del Giudice et al., 2015; Łukasik, 2021). ...
Purpose: Establishing the way the life history (LH) strategies and gratitude are related to each other. Design/methodology/approach: Life History Theory provides an evolutionary framework for understanding specific developmental paths of species and individuals. There are certain trade- offs during a lifespan of an individual, they must face (for instance, somatic or reproductive effort, quality or quantity of offspring, mating or parenting). Depending on the choices a person makes, they exhibit a slow or a fast life history (LH) strategy. A latent variable underlying a set of solutions (strategy) is called K-Factor and is used to measure individual differences with regard to the pace of one’s LH. People with a slow LH exhibit greater prosociality, tend to form long-term sexual relationships and their sexual maturation is slowed down. On the other hand, gratitude facilitates prosociality and altruism, builds social resources and acts as a moral barometer. In recent years we observe an increasing attention to the issue of gratitude both in academic publications and popular press in various fields including economics, management and organizational sciences. All these disciplines draw from relatively new and contemporarily flourishing field of psychology – positive psychology. We deployed the Gratitude Questionnaire (GQ-6) for the measurement of gratitude and the Mini-K Short Form for the measurement of LH strategies. 197 students took part in the study (138 females, 59 males). Findings: A positive correlation between slow LH strategy and gratitude was found in women. Originality/value: Investigations on the relationship between gratitude and LH strategies show a fragment of the landscape of human personality. Slow LH people seem to be more grateful and thus display more prosocial traits while restraining selfishness which can lead to achieving the delayed social benefits. On the other hand, low-K individuals in organizational context have smaller willingness/ability to reciprocate to their benefactors and to build social bonds. Such individuals presenting exploitative interpersonal style should be detected at the beginning of a selection process by HR specialists. Keywords: life history theory, life history strategies, gratitude, positive psychology, positive psychology interventions in organizations. Category of the paper: research paper.
... In particular, as early as in the 1970s, it became clear that, in modeling the processes of natural selection, factors such as the pressure of predators, the structure of resource distribution, the nature of abundance dynamics, and the differences in mortality of different age cohorts are inevitably taken into account (Gadgil and Bossert, 1970;Stearns, 1977;Reznick et al., 2002). By the 1980s, the ideas about this theory had changed dramatically, and in its original form it was practically no longer directly tested and used to interpret results (Reznick et al., 2002). ...
... Life history and evolutionary demographic theoretical frameworks consider fundamental processes that are universal across organisms such as birth, growth, reproduction, and death. The classic models are free from species-specific assumptions (e.g., [85][86][87][88]) and draw broad conclusions about the direction in which life history evolution should proceed if, for example, certain age classes experience selective mortality. The classic models then extend the calculation to the population level by conceptualizing the relative fitness differences among individuals along some phenotypic or external (e.g., environmental or food type) gradient, which provides the basis for natural selection [89]. ...
Phenology refers to the seasonal timing patterns commonly exhibited by life on Earth, from blooming flowers to breeding birds to human agriculture. Climate change is altering abiotic seasonality (e.g., longer summers) and in turn, phenological patterns contained within. However, how phenology should evolve is still an unsolved problem. This problem lies at the crux of predicting future phenological changes that will likely have substantial ecosystem consequences, and more fundamentally, of understanding an undeniably global phenomenon. Most studies have associated proximate environmental variables with phenological responses in case-specific ways, making it difficult to contextualize observations within a general evolutionary framework. We outline the complex but universal ways in which seasonal timing maps onto evolutionary fitness. We borrow lessons from life history theory and evolutionary demography that have benefited from a first principles-based theoretical scaffold. Lastly, we identify key questions for theorists and empiricists to help advance our general understanding of phenology.
... As discussed in chapter 10, reproductive success can be highly variable (Hairston et al., 1996a). Cole's paradox has been resolved by numerous models demonstrating that variation in reproductive success favors iteroparity (Murphy, 1968;Gadgil & Bossert, 1970;Schaffer, 1974;Wilbur et al., 1974;Bell, 1976Bell, , 1980Goodman, 1984;Bulmer, 1985;Orzack, 1985Orzack, , 1993Bradshaw, 1986;Roerdink, 1987;Orzack & Tuljapurkar, 1989Fox, 1993;Charlesworth, 1994;Cooch & Ricklefs, 1994;Erikstad et al., 1998;Benton & Grant, 1999;Brommer et al., 2000;Ranta et al., 2000aRanta et al., , 2000bRanta et al., , 2002Katsukawa et al., 2002;Wilbur & Rudolf, 2006).Thus, life history theory holds that in the face of annual resource variability, organisms should shift from semelparous to iteroparous reproductive patterns (Murphy, 1968;Bulmer 1985, Orzack & Tuljapurkar, 1989; and furthermore, under certain circumstances they should evolve a longer lifespan and reduced annual reproduction (Stearns, 1976;Gillespie, 1977;Roff, 2002;Nevoux et al., 2010). By this theory, bet-hedging evolves to reduce the probability of investing too much in reproduction during resource-poor years, which may ultimately result in null fitness. ...
How to cite the article:Heininger K. Duality of stochasticity and natural selection: a cybernetic evolution theory. WebmedCentral ECOLOGY 2015;6(2):WMC004796
... Life history theory predicts that reduced adult survival will select for earlier maturation and increased reproductive effort; conversely, reduced juvenile survival will select for the opposite (Gadgil & Bossert 1970;Charnov & Schaffer 1973;Law 1979;Michod 1979;Charlesworth 1980;Kozłowski & Wiegert 1987;Reznick et al. 1990;Lester et al. 2004). This is supported by laboratory studies (Sokal 1970;Mertz 1975;Barclay & Gregory 1981;Mueller & Ayala 1981;Rose & Charlesworth 1981;Rose 1984;Luckinbill & Clare 1985, 1986) and by comparative data from natural populations such as Trinidadian guppies, overexploited fish populations, and Tasmanian devils (Tinkle & Ballinger 1972;Stearns 1976Stearns , 1977Stearns , 1980Stearns , 1983Law et al. 1977;Leggett & Carscadden 1978;Reznick & Endler 1982). ...
... The classic models are free from species-specific assumptions (e.g. [77][78][79][80]), and draw broad conclusions about the direction in which life-history evolution should proceed if, for example, certain age classes experience selective mortality. The classic models then extend the calculation to the population level by conceptualizing the relative fitness differences among individuals along some phenotypic or external (e.g. ...
... Consequently, density-dependent effects are the main selective forces determining where a species falls on the r/ K continuum. Generally, it has been suggested that there is a trade-off between rand K-selection (Gadgil and Bossert 1970), although this hypothesis has been supported in some systems (e.g., Mueller et al. 1991), but not in others (Kerfoot 1977). Pianka (1970) further developed r/ K selection theory to include predictions of specific life history traits expected in stable or unstable environments. ...
This is the sixth volume of a ten-volume series on The Natural History of the Crustacea. The volume synthesizes in nineteen chapters our current understanding of diverse topics in crustacean reproductive biology. The first part of the volume address allocation strategies to reproduction, gamete production, brooding behavior and other components of parental care in crustaceans. The second part of the volume centers on sexual systems in crustaceans. The third section of the volume covers crustacean mating systems and sexual selection. The volume ends with three chapters covering diverse topics including reproductive rhythms, and crustacean personality research, and record breaking crustaceans with respect to reproductive characters. Collectively, these nineteen chapters provide an integrative and comprehensive treatment of crustacean reproductive biology from gamete formation to mating and reproductive strategies and their evolutionary and ecological consequences.
... The classic models are free from species-specific assumptions (e.g. [77][78][79][80]), and draw broad conclusions about the direction in which life-history evolution should proceed if, for example, certain age classes experience selective mortality. The classic models then extend the calculation to the population level by conceptualizing the relative fitness differences among individuals along some phenotypic or external (e.g. ...
Phenology refers to the seasonal timing patterns commonly exhibited by life on Earth, from blooming flowers to breeding birds to human agriculture. Climate change is altering abiotic seasonality (e.g. longer summers) and in turn, the phenological patterns contained within. However, how phenology evolves is still an unsolved problem. This problem lies at the crux of predicting future phenological changes that will likely have substantial ecosystem consequences, and more fundamentally, of understanding an undoubtedly global phenomenon. Most studies have associated proximate environmental variables with phenological responses in ways that are case-specific, making it difficult to contextualize observed changes within a general evolutionary framework. We advocate for general theory of phenological evolution centered around constructing null hypotheses to explain the disparate cases of phenological change in a systematic manner, and to distinguish when cases are surprising, and why. We outline the necessarily complex but universal ways in which timing within seasonal windows map onto evolutionary fitness. Throughout, we borrow lessons from life history theory and evolutionary demography that have benefited from a more first principles-based theoretical scaffold. Lastly, we identify key questions for theorists and empiricists to help synthesize and advance our general understanding of phenology.
... ife history results from three processes: survival, growth, and reproduction (Stearns 1992). These processes compete for limited resources; consequently, life history is an optimal allocation among them (Gadgil & Bossert 1970;Reekie & Bazzaz 2005). Many studies of reproductive strategies have been published, mostly with plants (e.g., Coelho et al. 2006Demetrio et al. 2014). ...
Reproductive strategies in lichens are a rarely studied field, and little is known about which variables affecting the production of reproductive structures are most important. Here, we investigated how lichen size and cardinal direction affected the density of apothecia in the cyanolichen Leptogium marginellum. We hypothesized that larger thalli and thalli facing south (towards the pole) would have a higher density of apothecia. Individuals with larger body sizes may store more resources that can be invested in sexual reproduction, and thalli facing south in the southern hemisphere could be exposed to more favorable abiotic conditions, similar to the north in the northern hemisphere. We collected L. marginellum thalli along a stream in a protected southeast Brazil area. Cardinal directions and the largest diameter of each thallus were registered with a GPS and a digital pachymeter, respectively. We observed the thalli with a stereomicroscope, delimited a region of 1×1 cm, and photographed it to count the number of apothecia with ImageJ. We found that cardinal direction did not affect the body size or the density of apothecia. However, lichen size was an important variable in the density of apothecia, explaining almost 60% of the variation observed. According to our findings, reproduction can be considered an allometric process, and reproductive patterns can vary with the hemisphere where the lichen is found. To our knowledge, this is the first research studying reproductive allocation in a tropical lichen.
... Historically the trade-off was viewed by the theory of r and K selection based on logistic model of growth (MacArthur and Wilson 1967;Reznick et al., 2002). The r and K selection theory came under criticism later and a more elaborate lifehistory optimization theory was proposed (Pianka 1970, Gadgil & Bossert 1970, Michod 1979, Kozlowski 1980, Charlesworth 1980, Stearns 1976, 1992, Derek 1993, Vitzthum, 2008. The life-history optimization also talks about optimum investment per offspring. ...
Among the classical models of optimization, some models maximize the ratio of returns to investment, others maximize the difference between returns and investment. However, an understanding of under what conditions the ratio or the difference approaches, are appropriate is still fragmentary. Under specific contexts it has been stated that when the investable amount, but not the opportunity for investment, is perceived to be limiting, a ratio optimum is appropriate, whereas a difference optimum is appropriate when the opportunity for investment, but not the investable amount is perceived to be limiting. The question is important because the strategies indicated by ratio optimum can be substantially different than the ones suggested by difference optimum. We make a general case here to examine and expand this principle and apply it to many evolutionary ecological problems including parental investment, offspring quality quantity trade‐off, nectar production, pollinator behavior viral burst size and intracellular protein handling We show that the ratio‐difference distinction in optimization models resolves many long‐standing debates and conundrums in evolution and behavior. This article is protected by copyright. All rights reserved
... The modern field of life history has embraced trade-offs, developing biologically informed mathematical and predictive models for how and why organisms differentially allocate their energetic resources among competing tasks [3][4][5][6][7][8][9][10][11][12][13][14] . These models have been remarkably successful in elucidating patterns of growth, reproduction, and senescence across the tree of life, and they share a common theoretical foundation: resources (typically energy, although the currency is not always explicitly stated) are allocated to growth, reproduction, and maintenance tasks in ways that maximize reproductive fitness in an organism's particular ecological niche. ...
Economic models predominate in life history research, which investigates the allocation of an organism's resources to growth, reproduction, and maintenance. These approaches typically employ a heuristic Y model of resource allocation, which predicts trade-offs among tasks within a fixed budget. The common currency among tasks is not always specified, but most models imply that metabolic energy, either from food or body stores, is the critical resource. Here, we review the evidence for metabolic energy as the common currency of growth, reproduction, and maintenance, focusing on studies in humans and other vertebrates. We then discuss the flow of energy to competing physiological tasks (physical activity, maintenance, and reproduction or growth) and its effect on life history traits. We propose a Ψ model of energy flow to these tasks, which provides an integrative framework for examining the influence of environmental factors and the expansion and contraction of energy budgets in the evolution of life history strategies.
... Organisms' energy budgets must be split among survival, growth, and reproduction (Gadgil & Bossert, 1970;Stearns, 1976). In bivalves, lifetime patterns of energy allocation are directly linked to individuals' shell-tissue growth ratio (i.e., structural allocation) and ontogenetic period (McMahon & Bogan, 2001;Labecka & Czarnoleski, 2019). ...
Respiration is a central physiological function related to the rates of energy acquisition, transformation, and use by organisms, while allometric relationships provide insight into patterns of allocation of that energy. To assess life strategy differences between closely related invasive species, we measured oxygen consumption rates, tissue mass, shell mass, and gill area of Corbicula fluminea and C. largillierti clams. We compared patterns of metabolic scaling between the two species using model II regressions. Although oxygen consumption rates were strongly associated with gill area in both species, C. fluminea had consistently higher metabolic rates, shell thickness, and shell mass, but a lower tissue-to-shell mass ratio, than C. largillierti. These differences were more marked among small individuals. Our results suggest opposite structural allocation strategies between the two species. Corbicula fluminea invests more energy in the development of thicker shells in early life stages, which can be subsidized by higher metabolic rates than C. largillierti. By contrast, C. largillierti allocates more energy to tissue mass production. These differences may play a role in explaining contrasting competitive and colonization abilities and geographical distribution patterns between both species in invaded areas.
Системно представлена субъектная концепция аутентичности личности — черты личности, обеспечивающей верность человека своей природе, пространственно-временным обстоятельствам жизни и предназначению. Две основные функции аутентичности, трансцендентная и адаптивная, способствуют адекватному контакту с миром через просоциальные (в том числе моральные) установки и поддержанию психологического благополучия. Субъектная концепция представлена в семи положениях и верифицирована эмпирически. В корреляционном исследовании приняли участие 430 респондентов в возрасте от 17 до 32 лет (Ср. возраст - 19.20±1.22 леь), 88 мужчин и 342 женщины. Измерялись показатели об¬щего благополучия, позитивного и негативного аффекта и моральных мотивов; условно независимыми переменными были восемь показателей аутентичности, представляющих три модели. Проверялось три гипотезы: 1) диспозициональная аутентичность положительно связана с психологическим благополучием человека; 2) диспозициональная аутентичность положительно связана с моральными мотивами человека; 3) индикаторы диспозициональной аутентичности в рамках разных парадигм образуют разные паттерны связей с показателями благополучия и моральными мотивами. Все три гипотезы подтвердились (вторая — частично). Регрессионные модели для психологического благополучия оказались сильнее тех, что предсказывают моральные мотивы, а показатель аутентичности в рамках субъектной концепции образует наибольшее количество связей со всеми изученными переменными, подтверждая адаптивную и трансцендентную функцию аутентичности.
Life history strategies are shaped by phylogeny, environmental conditions and individual energy budgets, and have implications for population performance. Here, we used an approach that merges demography with energy budget theory to structure life history traits of 151 elasmobranch species into life history strategies for two contrasting feeding levels. We assessed how phylogeny and habitat impacted life history strategies, and tested if these strategies predict population performance and conservation status. Elasmobranch life history strategies are structured along the fast-slow continuum and reproductive strategy axes. However, species' positions in this life history space were not fixed, but instead moved in an anticlockwise 'whirlpool' manner along the two axes in response to an increase in feeding level. We also found that population growth rate does not necessarily inform on a species demographic resilience. Finally, only at the higher feeding level does the fast-slow continuum predict IUCN conservation status, with the slowest species at the highest risk of extinction. Our analyses reveal plasticity in species life history strategies, and warn against extrapolating the fast-slow continuum and reproductive strategy framework from one environment to another when predicting a species' response to (climate) change, perturbations, and, particularly in case of elasmobranchs, (over)exploitation.
The leaves of many trees emit volatile organic compounds (abbreviated as BVOCs), which protect them from various damages, such as herbivory, pathogens, and heat stress. For example, isoprene is highly volatile and is known to enhance the resistance to heat stress. In this study, we analyze the optimal seasonal schedule for producing isoprene in leaves to mitigate damage. We assume that photosynthetic rate, heat stress, and the stress-suppressing effect of isoprene may vary throughout the season. We seek the seasonal schedule of isoprene production that maximizes the total net photosynthesis using Pontryagin's maximum principle. The isoprene production rate is determined by the changing balance between the cost and benefit of enhanced leaf protection over time. If heat stress peaks in midsummer, isoprene production can reach its highest levels during the summer. However, if a large portion of leaves is lost due to heat stress in a short period, the optimal schedule involves peaking isoprene production after the peak of heat stress. Both high photosynthetic rate and high isoprene volatility in midsummer make the peak of isoprene production in spring. These results can be clearly understood by distinguishing immediate impacts and the impacts of future expectations.
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The importance of studying the phenomenon of personal authenticity as loyalty to one’s true Self is substantiated. Historical and cultural prototypes of this phenomenon are considered. The difference between the Eastern and Western traditions of understanding the true Self is noted: in the East, a person’s dialogue with the world was implied, whereas in the West — internal harmony was. Four basic oppositions are proposed to describe authenticity: to have vs to be (adaptation vs meaning); source vs effect vs epiphenomenon; molecular vs molar; internal vs external. The main function of authenticity is identified as monitoring the meaningfulness of life lived by a person in accordance with their unique calling.
The contemporary descriptive and operationalized concepts of authenticity are compared; their limitations when transferred to Russian culture are noted. The original agent conception of authenticity is proposed, understood as a person’s loyalty to their individuality, the space-time context of their life and life-calling. The status of authenticity in this sense is a trait like sensitivity to situations. The agent conception is supported by the Moscow Authenticity Scale as the main standardized measurement tool. The resource role of authenticity in stress situations of various nature is discussed. Based on the data on the impact of negative life events obtained in various fields of psychology, a hypothetical model of the possible change and genesis under the influence of stress is substantiated.
Рассматривается феномен аутентичности личности как верности своему истинному Я в соотнесении с переживанием стресса. Анализируются философские, исторические и культурные прототипы этого феномена. Отмечается различие восточной и западной традиций пони-мания истинного Я (в восточной-диалог человека с миром, в запад-ной-внутреннее согласие). Предлагаются четыре базовых оппозиции для описания аутентичности: иметь vs быть (адаптация vs смысл); источник vs эффект vs эпифеномен; молекулярное vs молярное; внутреннее vs внешнее. Идентифицируется основная функция аутентичности как мониторинга осмысленности жизни, проживаемой человеком в соответствии с его уникальным предназначением. Сопоставляются современные описательные и операционализированные концепции аутентичности личности, разработанные в рамках личностно ориентированной и экзистенциальной психологии; отмечаются ограничения данных концепций при переносе на российскую культуру. Предлагается авторская субъектная концепция аутентичности, понимаемой как верность человека своей индивидуальности, пространственно-временному контексту
своей жизни и предназначению. Онтологический статус аутентичности
в этом понимании — присущая человеку такая черта, как чувствительность к ситуациям. Субъектная концепция подкреплена Московской
шкалой аутентичности как основным стандартизированным инструментом измерения. Обсуждается ресурсная роль аутентичности в ситуациях стрессов различной природы. С опорой на данные о влиянии негативных жизненных событий, полученные в разных областях психологии, обосновывается гипотетическая модель возможного изменения и генезиса аутентичности под влиянием стресса.
The theory of density-dependent selection posits that genotypic fitness can vary depending on the population density. Several long-term selection experiments on outbred populations of Drosophila adapted to chronically high larval densities have shown that the most common evolutionary response of such rearing is an increase in larval competitive ability. Some authors have proposed that a better understanding of the evolution of competitive ability can be achieved by its partitioning into effectiveness and tolerance components. Effectiveness is the amount of competitive inhibition imposed by a competitor on another, whereas tolerance is the degree to which a competitor can withstand inhibition. In this study, we have explored the evolution of effectiveness and tolerance components of competitive ability using three sets of outbred populations of D. melanogaster adapted to chronic larval crowding at different respective combinations of egg number, food volume and container dimensions. Effectiveness and tolerance were found to be dependent on the particular selection regime, the starting food amount and the trait used as the outcome of competition. Eclosion, dry biomass and dry weight per fly distributions over time indicated that competitive ability can also express itself in a time-dependent manner. The results suggest that larval competition and the evolution of competitive ability in Drosophila are extremely nuanced.
The age and parity of female primates reflects their physical condition and reproductive experience. Individual age-parity dependent condition of females and the survival of their offspring represents a fitness tradeoff. This reproductive tradeoff is expressed in the individual birth sex ratio, offspring mortality and interbirth interval (IBI). Thus, maternal antenatal and postnatal investment hypotheses argue that, dependent on their physical condition determined by available resources, mothers can adjust the birth sex ratio, offspring mortality, and IBI. These hypotheses predict that more female offspring are produced by experienced mothers in poor condition (Trivers-Willard hypothesis), and that offspring mortality decreases and IBI shortens with parity (targeted reproductive effort hypothesis). Here we test the latter predictions in captive populations of the endangered Francois’ langur (Trachypithecus francoisi), using long-term (1980 to 2021) demographic and reproductive data from 21 Chinese zoos and three breeding centers. In these food provisioned populations, birth sex ratio changed slightly from male-biased to female-biased as parity increased, consistent with the predictions of the Trivers-Willard hypothesis. Although mortality of male offspring was greater than female offspring, overall offspring mortality did not vary with parity among females. The duration of postnatal care or IBI of male offspring was significantly shorter than for female offspring. However, IBI did shorten significantly, even for male offspring, with increasing parity, as predicted by the targeted reproductive effort hypothesis. Selecting females with more reproductive experience is recommended for captive breeding programs as they produce more female offspring, increasing the overall viable population size of this endangered species.
Maturation strategies play a key role in the survival and development of populations. In response to changes in the external environment and human interventions, populations adopt appropriate maturation strategies. Different maturation strategies can lead to different birth and mortality rates. In this paper, we develop and analyze a stage-structured population model with two maturation strategies to obtain conditions for the coexistence of two maturation strategies and conditions for competitive exclusion. Our results also show that equality of fitness—represented by basic reproductive numbers being greater than 1 under different maturation strategies—promotes the coexistence of the two strategies. The reason why a strategy is replaced by another one is that the population adopting this strategy has weak fitness, which is measured by the basic reproductive number.
Complex life histories are frequently associated with biological trade-offs, as the use of one trait can decrease the performance of a second trait due to the need to balance competing demands to maximize fitness. Here, we examine growth patterns in invasive adult male northern crayfish (Faxonius virilis) that are indicative of a potential trade-off between energy allocation for body size versus chelae size growth. Northern crayfish undergo cyclic dimorphism, a process characterized by seasonal morphological changes associated with reproductive status. We measured carapace length and chelae length before and after molting and compared these growth increments between the four morphological transitions of the northern crayfish. Consistent with our predictions, reproductive crayfish molting to the non-reproductive form and non-reproductive crayfish molting within the non-reproductive form experienced a larger carapace length growth increment. Reproductive crayfish molting within the reproductive form and non-reproductive crayfish molting to the reproductive form, on the other hand, experienced a larger growth increment in chelae length. The results of this study support that cyclic dimorphism evolved as a strategy for optimizing energy allocation for body and chelae size growth during discrete periods of reproduction in crayfish with complex life histories.
How organisms capture and ultimately use metabolic energy-a limiting resource of life-has profound implications for understanding evolutionary legacies and current patterns of phenotypic variation, adaptation, and health. Energetics research among humans has a rich history in biological anthropology and beyond. The energetics of childhood, however, remains relatively underexplored. This shortcoming is notable given the accepted importance of childhood in the evolution of the unique human life history pattern as well as the known sensitivity of childhood development to local environments and lived experiences. In this review, I have three objectives: (1) To overview current knowledge regarding how children acquire and use energy, highlighting work among diverse human populations and pointing to recent advances and remaining areas of uncertainty; (2) To discuss key applications of this knowledge for understanding human variation, evolution, and health; (3) To recommend future avenues for research. A growing body of evidence supports a model of trade-offs and constraint in childhood energy expenditure. This model, combined with advancements on topics such as the energetics of immune activity, the brain, and the gut, provides insights into the evolution of extended human subadulthood and the nature of variation in childhood development, lifetime phenotype, and health.
Variations in the reproductive and survival abilities of individuals within a population are ubiquitous in nature, key to individual fitness, and affect population dynamics, which leads to strong interest in understanding causes and consequences of vital‐rate variation. For long‐lived species, long‐term studies of large samples of known‐age individuals are ideal for evaluating vital‐rate variation.
A population of Weddell seals in Erebus Bay, Antarctica, has been studied each Austral spring since the 1960s. Since 1982, all newborns have been tagged each year and multiple capture‐mark‐recapture (CMR) surveys have been conducted annually.
Over the past 20 years, a series of analyses have built on results of earlier research by taking advantage of steady improvements in the project's long‐term CMR data and available analytical methods. Here, I summarize progress made on four major topics related to variation in age‐specific vital rates for females: early‐life survival and age at first reproduction, costs of reproduction, demographic buffering, and demographic senescence.
Multistate modelling found that age at first reproduction varies widely (4–14 years of age) and identified contrasting influences of maternal age on survival and recruitment rates of offspring. Subsequent analyses of data for females after recruitment revealed costs of reproduction to both survival and future reproduction and provided strong evidence of demographic buffering. Recent results indicated that important levels of among‐individual variation exist in vital rates and revealed contrasting patterns for senescence in reproduction and survival.
Sources of variation in vital rates include age, reproductive state, year, and individual. The combination of luck and individual quality results in strong variation in individual fitness outcomes: ~80% of females born in the population produce no offspring, and the remaining 20% vary strongly in lifetime reproductive output (range: 1–23 pups).
Further research is needed to identify the specific environmental conditions that lead to annual variation in vital rates and to better understand the origins of individual heterogeneity. Work is also needed to better quantify the relative roles of luck, maternal effects, and environmental conditions on variation in vital rates and to learn the importance of such variation to demographic performance of offspring and on overall population dynamics.
Understanding how changing environmental conditions affect fish growth and reproduction is critical to predict the consequences of climate change, yet studies focused on the physiological effects of temperature upon life histories often ignore size-dependent foraging and risk of predation. We embedded a state-dependent energetic model in an ecosystem size spectrum model to characterize prey availability (foraging) and risk of predation (fear) experienced by individual fish as they grow. We examined how spectrum richness and temperature interact to shape growth, reproduction, and survival; we found that richer spectra led to larger body sizes, but effects of temperature on body size were small. We applied our model to scenarios corresponding to three ecological lifestyles (ecotypes) of tunas, in some cases including seasonal variation in conditions. We predicted realistic estimates of growth and body sizes of tunas and found that seasonality in resources and temperature could lead to giant body sizes (> 300 cm), due to the compression of reproduction into shorter timeframes. Our framework for predicting emergent life histories combines direct and indirect effects of productivity (foodscapes), individual risk (fearscapes), and metabolic processes. This approach can be used to reconcile disparate results on fish life history responses to changing ocean conditions.
General evolutionary theory predicts that individuals in low condition should invest less in sexual traits compared to individuals in high condition. Whether this positive association between condition and investment also holds between young (high condition) and senesced (low condition) individuals is however less clear, since elevated investment into reproduction may be beneficial when individuals approach the end of their life. To address how investment into sexual traits changes with age, we study genes with sex-biased expression in the brain, the tissue from which sexual behaviours are directed. Across two distinct populations of Drosophila melanogaster, we find that old brains display fewer sex-biased genes, and that expression of both male-biased and female-biased genes converges towards a sexually intermediate phenotype owing to changes in both sexes with age. We further find that sex-biased genes in general show heightened age-dependent expression in comparison to unbiased genes and that age-related changes in the sexual brain transcriptome are commonly larger in males than females. Our results hence show that ageing causes a desexualization of the fruit fly brain transcriptome and that this change mirrors the general prediction that low condition individuals should invest less in sexual phenotypes.
Demographic costs of reproduction in flowering plants should depend on life history and reproductive efforts, but how the expression of costs varies with life‐history traits is poorly understood.
We experimentally increased and reduced reproductive effort (fruit production) to quantify demographic costs of reproduction in four coexisting species with contrasting growth forms (clonal vs. non‐clonal) and flower production (single‐ vs. multi‐flowered). We repeated the experiment for 3 years and measured the demographic rates the year after the treatment. In 2 years, we also quantified the costs of flower maintenance by contrasting the performance of non‐fruiting plants with intact flowers and plants with their flowers removed.
Costs varied among species, in both magnitude and demographic rate affected. Costs of natural reproduction were expressed as reductions in size and fecundity next year, whereas increased reproduction additionally reduced sprouting probability. The magnitude of demographic costs of both reproduction and flower maintenance was highest in the non‐clonal, multi‐flowered species, and costs were more frequently detected in the two multi‐flowered species than in the single‐flowered ones. This may be explained by higher biomass allocation to reproductive parts and a longer flowering period in the former. Demographic costs of reproduction did not depend on clone size.
Synthesis. These results document that demographic costs vary among coexisting species sharing similar niches and are associated with divergence in life‐history traits. Such trait‐dependent variation in costs may reduce competition among coexisting species and facilitate diversity.
Life history theory provides a framework to understand environmental change based on species strategies for survival and reproduction under stable, cyclical, or stochastic environmental conditions. We evaluated environmental predictors of fish life history strategies in 20 streams intersecting a national park within the Potomac River basin in eastern North America. We sampled stream sites during 2018–2019 and collected 3801 individuals representing 51 species within 10 taxonomic families. We quantified life history strategies for species from their coordinates in an ordination space defined by trade‐offs in spawning season duration, fecundity, and parental care characteristic of opportunistic, periodic, and equilibrium strategies. Our analysis revealed important environmental predictors: Abundance of opportunistic strategists increased with low‐permeability soils that produce flashy runoff dynamics and decreased with karst terrain (carbonate bedrock) where groundwater inputs stabilize stream flow and temperature. Conversely, abundance of equilibrium strategists increased in karst terrain indicating a response to more stable environmental conditions. Our study indicated that fish community responses to groundwater and runoff processes may be explained by species traits for survival and reproduction. Our findings also suggest the utility of life history theory for understanding ecological responses to destabilized environmental conditions under global climate change. We show that species traits for survival and reproduction explain fish community responses to groundwater and runoff processes in headwater streams. Our results also indicate the utility of life history theory for understanding ecological responses to destabilized environmental conditions under global climate change.
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