Life-history tradeoffs

@misc{calder1984size8,
    author = "Calder, WA",
    title = "Size Function and Life History",
    year = "1984",
    note = "discovered\_from = {doi101371journalpone0163205}"
}

@incollection{iii1984size21,
    author = "III, WA Calder",
    title = "Size, function, and life history",
    year = "1984",
    note = "discovered\_from = {doi101007s0042701605392}"
}

@book{openalexw1558456135,
    author = "Calder, William A.",
    title = "Size, Function, and Life History",
    year = "1984",
    journal = "Medical Entomology and Zoology",
    openalex = "W1558456135"
}

@article{doi1023072408653,
    author = "Harvey, Paul H. and Clutton-Brock, T. H.",
    title = "Life History Variation in Primates",
    year = "1985",
    journal = "Evolution",
    url = "https://doi.org/10.2307/2408653",
    doi = "10.2307/2408653",
    note = "discovered\_from = {doi101016004724849290081j}",
    number = "3",
    pages = "559",
    volume = "39"
}

Life history theory suggests that the optimal evolved level of reproductive effort (RE) for an organism depends upon the degree to which additional current reproductive investment reduces future reproductive output. Future reproduction can be decreased in two ways, through (i) decreases in the organism's survival rate, and/or (ii) decreases in the organism's growth (and hence subsequent fecundity). The latter tradeoff-that is, the "potential fecundity cost"-should affect the evolution of RE only in species with relatively high survival rate, a relatively high rate of fecundity increase with body size, or a relatively high reproductive frequency per annum. Unless these conditions are met, the probable benefit in future fecundity obtained from decreasing present reproductive output is too low for natural selection to favor any reduction in RE below the maximum physiologically possible. Published data on survival rate, reproductive frequency and relative clutch mass (RCM) suggest that many lizard species fall well below the level at which natural selection can be expected to influence RE through such "potential fecundity" tradeoffs. Hence, the relative allocation of resources between growth and reproduction is unlikely to be directly optimized by natural selection in these animals. Instead, energy allocation should influence the evolution of RE only indirectly, via effects on an organism's probability of survival during reproduction. Survival costs of reproduction may be the most important evolutionary determinants of RE in many reptiles, and information on the nature and extent of such costs is needed before valid measures of reptilian RE can be constructed.

@article{doi101111j155856461992tb01985x,
    author = "Shine, Richard and Schwarzkopf, Lin",
    title = "THE EVOLUTION OF REPRODUCTIVE EFFORT IN LIZARDS AND SNAKES",
    year = "1992",
    journal = "Evolution",
    abstract = {Life history theory suggests that the optimal evolved level of reproductive effort (RE) for an organism depends upon the degree to which additional current reproductive investment reduces future reproductive output. Future reproduction can be decreased in two ways, through (i) decreases in the organism's survival rate, and/or (ii) decreases in the organism's growth (and hence subsequent fecundity). The latter tradeoff-that is, the "potential fecundity cost"-should affect the evolution of RE only in species with relatively high survival rate, a relatively high rate of fecundity increase with body size, or a relatively high reproductive frequency per annum. Unless these conditions are met, the probable benefit in future fecundity obtained from decreasing present reproductive output is too low for natural selection to favor any reduction in RE below the maximum physiologically possible. Published data on survival rate, reproductive frequency and relative clutch mass (RCM) suggest that many lizard species fall well below the level at which natural selection can be expected to influence RE through such "potential fecundity" tradeoffs. Hence, the relative allocation of resources between growth and reproduction is unlikely to be directly optimized by natural selection in these animals. Instead, energy allocation should influence the evolution of RE only indirectly, via effects on an organism's probability of survival during reproduction. Survival costs of reproduction may be the most important evolutionary determinants of RE in many reptiles, and information on the nature and extent of such costs is needed before valid measures of reptilian RE can be constructed.},
    url = "https://doi.org/10.1111/j.1558-5646.1992.tb01985.x",
    doi = "10.1111/j.1558-5646.1992.tb01985.x",
    openalex = "W2334627950"
}

Abstract Earlier experiments have shown that the evolution of postponed senescent populations can be achieved by selection on either demographic or stress resistance characters. Both types of selection have produced results in which survival characters (stress resistance and longevity) have apparently traded‐off against early‐life fecundity. Here we present the results of a series of experiments in which an environmental variable — the level of live yeast inoculate applied to the substrate — produces a qualitatively similar phenotypic response: longevity and starvation resistance are enhanced by lower yeast levels, at the expense of fecundity. For the starvation resistance versus fecundity experiments we show a negative and linear relationship between the norms of reaction for each character across a gradient of yeast levels. This phenotypic trade‐off is stable across the 20 populations and 4 selection treatments reported on here, and its general agreement with earlier selection results suggests that the evolutionary response and the phenotypically plastic response may share a common physiological basis. However, an important discrepancy in the lifetime fecundity data between the selection response and the dietary manipulations preclude strict analogy. The results broadly conform to a simple “Y‐model” of allocation, in which a limited resource is divided between survival and reproduction; here the characters are starvation resistance and longevity versus fecundity.

@article{doi101046j1420910119936020171x,
    author = "Chippindale, Adam K. and Leroi, Armand M. and Kim, Sung B. and Rose, Michael R.",
    title = "Phenotypic plasticity and selection in Drosophila life‐history evolution. I. Nutrition and the cost of reproduction",
    year = "1993",
    journal = "Journal of Evolutionary Biology",
    abstract = "Abstract Earlier experiments have shown that the evolution of postponed senescent populations can be achieved by selection on either demographic or stress resistance characters. Both types of selection have produced results in which survival characters (stress resistance and longevity) have apparently traded‐off against early‐life fecundity. Here we present the results of a series of experiments in which an environmental variable — the level of live yeast inoculate applied to the substrate — produces a qualitatively similar phenotypic response: longevity and starvation resistance are enhanced by lower yeast levels, at the expense of fecundity. For the starvation resistance versus fecundity experiments we show a negative and linear relationship between the norms of reaction for each character across a gradient of yeast levels. This phenotypic trade‐off is stable across the 20 populations and 4 selection treatments reported on here, and its general agreement with earlier selection results suggests that the evolutionary response and the phenotypically plastic response may share a common physiological basis. However, an important discrepancy in the lifetime fecundity data between the selection response and the dietary manipulations preclude strict analogy. The results broadly conform to a simple “Y‐model” of allocation, in which a limited resource is divided between survival and reproduction; here the characters are starvation resistance and longevity versus fecundity.",
    url = "https://doi.org/10.1046/j.1420-9101.1993.6020171.x",
    doi = "10.1046/j.1420-9101.1993.6020171.x",
    openalex = "W4245403460"
}

@incollection{doi101016b9780123847195000873,
    author = "Roff, Derek",
    title = "Life History, Evolution of",
    year = "2001",
    booktitle = "Encyclopedia of Biodiversity",
    url = "https://doi.org/10.1016/b978-0-12-384719-5.00087-3",
    doi = "10.1016/b978-0-12-384719-5.00087-3",
    note = "discovered\_from = {doi101126science1074085}",
    pages = "631-641"
}

@incollection{da2002life9,
    author = "DA, Roff",
    title = "Life History Evolution",
    year = "2002",
    note = "discovered\_from = {doi101073pnas0701489104}"
}

@article{doi101016s0169534702025788,
    author = "Ricklefs, Robert E. and Wikelski, Martin",
    title = "The physiology/life-history nexus",
    year = "2002",
    journal = "Trends in Ecology \& Evolution",
    url = "https://doi.org/10.1016/s0169-5347(02)02578-8",
    doi = "10.1016/s0169-5347(02)02578-8",
    note = "discovered\_from = {doi101111j14668238201100737x}",
    number = "10",
    pages = "462-468",
    volume = "17"
}

We investigated the quantitative genetics of plasticity in resource allocation between survival, growth and reproductive effort in Crassostrea gigas when food abundance varies spatially. Resource allocation shifted from survival to growth and reproductive effort as food abundance increased. An optimality model suggests that this plastic shift may be adaptive. Reproductive effort plasticity and mean survival were highly heritable, whereas for growth, both mean and plasticity had low heritability. The genetic correlations between reproductive effort and both survival and growth were negative in poor treatments, suggesting trade-offs, but positive in rich ones. These sign reversals may reflect genetic variability in resource acquisition, which would only be expressed when food is abundant. Finally, we found positive genetic correlations between reproductive effort plasticity and both growth and survival means. The latter may reflect adaptation of C. gigas to differential sensitivity of fitness to survival, such that genetic variability in survival mean might support genetic variability in reproductive effort plasticity.

@article{doi101046j14209101200300674x,
    author = "Ernande, Bruno and Boudry, Pierre and Clobert, Jean and Haure, Joël",
    title = "Plasticity in resource allocation based life history traits in the Pacific oyster, Crassostrea gigas. I. Spatial variation in food abundance",
    year = "2004",
    journal = "Journal of Evolutionary Biology",
    abstract = "We investigated the quantitative genetics of plasticity in resource allocation between survival, growth and reproductive effort in Crassostrea gigas when food abundance varies spatially. Resource allocation shifted from survival to growth and reproductive effort as food abundance increased. An optimality model suggests that this plastic shift may be adaptive. Reproductive effort plasticity and mean survival were highly heritable, whereas for growth, both mean and plasticity had low heritability. The genetic correlations between reproductive effort and both survival and growth were negative in poor treatments, suggesting trade-offs, but positive in rich ones. These sign reversals may reflect genetic variability in resource acquisition, which would only be expressed when food is abundant. Finally, we found positive genetic correlations between reproductive effort plasticity and both growth and survival means. The latter may reflect adaptation of C. gigas to differential sensitivity of fitness to survival, such that genetic variability in survival mean might support genetic variability in reproductive effort plasticity.",
    url = "https://doi.org/10.1046/j.1420-9101.2003.00674.x",
    doi = "10.1046/j.1420-9101.2003.00674.x",
    openalex = "W1592728659"
}

Life history theory hypothesises that breeding events induce reproductive costs that may vary among individuals. However, the growing number of studies addressing this question are taxonomically biased, therefore impeding the generalisation of this hypothesis, especially with regard to marine top predators. This study investigated age‐related survival and breeding performances in subantarctic fur seal (Arctocephalus tropicalis) females from Amsterdam Island, southern Indian Ocean. Using multistate capture–recapture models on data obtained from known‐age tagged females over eight consecutive years, we tested for evidence of senescence, individual quality, and reproductive costs in terms of future survival and fecundity. Adult female yearly survival appeared high and constant throughout time. While a two age‐class model was preferred in non‐breeders, breeding females exhibited three age classes with a maximum survival for the prime‐age class (7–12 years). Survival and reproductive probabilities decreased from 13 years onward, suggesting senescence in this population. Survival was lower for non‐breeders than for breeders, among both prime‐aged (0.938 vs 0.982) and older (0.676 vs 0.855) females. Furthermore, non‐breeders exhibited higher probabilities of being non‐breeders the following year than did breeders (0.555 vs 0.414). Such results suggest consistency in female breeding performance over years, supporting the hypothesis that non‐breeding tend to occur among lower quality individuals rather than representing an alternative strategy to enhance residual reproductive value. However, the high proportion of females that did not breed during two consecutive years, and the lower probability of being a successful breeder after a greater reproductive effort confirmed the existence of reproductive costs, especially during the second half of the lactation. These results also suggest that younger age‐classes included a higher proportion of lower quality individuals, which are likely to face higher costs of reproduction. Such hypotheses lead to consider the first breeding event as a filter generating a within‐cohort selection process in females.

@article{doi101111j00301299200614412x,
    author = "Beauplet, Gwénaël and Barbraud, Christophe and Dabin, Willy and Küssener, Clothilde and Guinet, Christophe",
    title = "Age‐specific survival and reproductive performances in fur seals: evidence of senescence and individual quality",
    year = "2006",
    journal = "Oikos",
    abstract = "Life history theory hypothesises that breeding events induce reproductive costs that may vary among individuals. However, the growing number of studies addressing this question are taxonomically biased, therefore impeding the generalisation of this hypothesis, especially with regard to marine top predators. This study investigated age‐related survival and breeding performances in subantarctic fur seal (Arctocephalus tropicalis) females from Amsterdam Island, southern Indian Ocean. Using multistate capture–recapture models on data obtained from known‐age tagged females over eight consecutive years, we tested for evidence of senescence, individual quality, and reproductive costs in terms of future survival and fecundity. Adult female yearly survival appeared high and constant throughout time. While a two age‐class model was preferred in non‐breeders, breeding females exhibited three age classes with a maximum survival for the prime‐age class (7–12 years). Survival and reproductive probabilities decreased from 13 years onward, suggesting senescence in this population. Survival was lower for non‐breeders than for breeders, among both prime‐aged (0.938 vs 0.982) and older (0.676 vs 0.855) females. Furthermore, non‐breeders exhibited higher probabilities of being non‐breeders the following year than did breeders (0.555 vs 0.414). Such results suggest consistency in female breeding performance over years, supporting the hypothesis that non‐breeding tend to occur among lower quality individuals rather than representing an alternative strategy to enhance residual reproductive value. However, the high proportion of females that did not breed during two consecutive years, and the lower probability of being a successful breeder after a greater reproductive effort confirmed the existence of reproductive costs, especially during the second half of the lactation. These results also suggest that younger age‐classes included a higher proportion of lower quality individuals, which are likely to face higher costs of reproduction. Such hypotheses lead to consider the first breeding event as a filter generating a within‐cohort selection process in females.",
    url = "https://doi.org/10.1111/j.0030-1299.2006.14412.x",
    doi = "10.1111/j.0030-1299.2006.14412.x",
    openalex = "W2101080537"
}

A strong case can be made for whole-organism performance traits (i.e., dynamic, ecologically relevant traits whose expression is shaped by underlying morphological factors) as being the ultimate integrative traits. This is not only because they capture the output of multiple lower levels of biological organization, but also because they are directly relevant to individual fitness in multiple ecological contexts, and are in many cases important proximate determinants of survival and/or reproductive success. But although many ecological and evolutionary phenomena can be examined through the lens of performance (and vice-versa), performance research has been surprisingly slow to incorporate concepts from the large and important field of life-history evolution. Such a synthesis is necessary, because shifts in resource allocation strategies can have implications for these highly ecologically relevant, functional traits, whose expression may trade-off against fecundity, immune function, or longevity, among other key life-history traits. The papers in this symposium showcase many of the ways in which life-history strategies can have direct consequences for the expression, maintenance, and evolution of whole-organism performance (and at least one case where they may not). By approaching the issue of life-history trade-offs from a number of diverse perspectives, this symposium reveals the scope for future explicit integration of life-history techniques with those of whole-organism performance studies for a more complete understanding of multivariate phenotypic evolution.

@article{doi101093icbicx084,
    author = "Lailvaux, Simon P and Husak, Jerry F",
    title = "Introduction to the Symposium: Integrative Life-History of Whole-Organism Performance.",
    year = "2017",
    journal = "Integrative and comparative biology",
    abstract = "A strong case can be made for whole-organism performance traits (i.e., dynamic, ecologically relevant traits whose expression is shaped by underlying morphological factors) as being the ultimate integrative traits. This is not only because they capture the output of multiple lower levels of biological organization, but also because they are directly relevant to individual fitness in multiple ecological contexts, and are in many cases important proximate determinants of survival and/or reproductive success. But although many ecological and evolutionary phenomena can be examined through the lens of performance (and vice-versa), performance research has been surprisingly slow to incorporate concepts from the large and important field of life-history evolution. Such a synthesis is necessary, because shifts in resource allocation strategies can have implications for these highly ecologically relevant, functional traits, whose expression may trade-off against fecundity, immune function, or longevity, among other key life-history traits. The papers in this symposium showcase many of the ways in which life-history strategies can have direct consequences for the expression, maintenance, and evolution of whole-organism performance (and at least one case where they may not). By approaching the issue of life-history trade-offs from a number of diverse perspectives, this symposium reveals the scope for future explicit integration of life-history techniques with those of whole-organism performance studies for a more complete understanding of multivariate phenotypic evolution.",
    url = "https://pubmed.ncbi.nlm.nih.gov/28859412/",
    doi = "10.1093/icb/icx084",
    pmid = "28859412"
}

Trade-offs in energy allocation between growth, reproduction, and survival are at the core of life-history theory. While age-specific mortality is considered to be the main determinant of the optimal allocation, some life-history strategies, such as delayed or skipped reproduction, may be better understood when also accounting for reproduction costs. Here, we present a two-pool indeterminate grower model that includes survival and energetic costs of reproduction. The energetic cost sets a minimum reserve required for reproduction, while the survival cost reflects increased mortality from low postreproductive body condition. Three life-history parameters determining age-dependent energy allocation to soma, reserve, and reproduction are optimized, and we show that the optimal strategies can reproduce realistic emergent growth trajectories, maturation ages, and reproductive outputs for fish. The model predicts maturation phase shifts along the gradient of condition-related mortality and shows that increased harvesting will select for earlier maturation and higher energy allocation to reproduction. However, since the energetic reproduction cost sets limits on how early an individual can mature, an increase in fitness at high harvesting can only be achieved by diverting most reserves into reproduction. The model presented here can improve predictions of life-history responses to environmental change and human impacts because key life-history traits such as maturation age and size, maximum body size, and size-specific fecundity emerge dynamically.

@article{doi101086698655,
    author = "Audzijonyte, Asta and Richards, Shane A",
    title = "The Energetic Cost of Reproduction and Its Effect on Optimal Life-History Strategies.",
    year = "2018",
    journal = "The American naturalist",
    abstract = "Trade-offs in energy allocation between growth, reproduction, and survival are at the core of life-history theory. While age-specific mortality is considered to be the main determinant of the optimal allocation, some life-history strategies, such as delayed or skipped reproduction, may be better understood when also accounting for reproduction costs. Here, we present a two-pool indeterminate grower model that includes survival and energetic costs of reproduction. The energetic cost sets a minimum reserve required for reproduction, while the survival cost reflects increased mortality from low postreproductive body condition. Three life-history parameters determining age-dependent energy allocation to soma, reserve, and reproduction are optimized, and we show that the optimal strategies can reproduce realistic emergent growth trajectories, maturation ages, and reproductive outputs for fish. The model predicts maturation phase shifts along the gradient of condition-related mortality and shows that increased harvesting will select for earlier maturation and higher energy allocation to reproduction. However, since the energetic reproduction cost sets limits on how early an individual can mature, an increase in fitness at high harvesting can only be achieved by diverting most reserves into reproduction. The model presented here can improve predictions of life-history responses to environmental change and human impacts because key life-history traits such as maturation age and size, maximum body size, and size-specific fecundity emerge dynamically.",
    url = "https://pubmed.ncbi.nlm.nih.gov/30205032/",
    doi = "10.1086/698655",
    pmid = "30205032"
}

Allocation of resources to competing processes of growth, maintenance, or reproduction is arguably a key process driving the physiology of life history trade-offs and has been shown to affect immune defenses, the evolution of aging, and the evolutionary ecology of offspring quality. Here, we develop a framework to investigate the evolutionary consequences of physiological dynamics by developing theory linking reproductive cell dynamics and components of fitness associated with costly resource allocation decisions to broader life history consequences. We scale these reproductive cell allocation decisions to population-level survival and fecundity using a life history approach and explore the effects of investment in reproduction or tissue-specific repair (somatic or reproductive) on the force of selection, reproductive effort, and resource allocation decisions. At the cellular level, we show that investment in protecting reproductive cells increases fitness when reproductive cell maturation rate is high or reproductive cell death is high. At the population level, life history fitness measures show that cellular protection increases reproductive value by differential investment in somatic or reproductive cells and the optimal allocation of resources to reproduction is moulded by this level of investment. Our model provides a framework to understand the evolutionary consequences of physiological processes underlying trade-offs and highlights the insights to be gained from considering fitness at multiple levels, from cell dynamics through to population growth.

@article{doi101002ece35477,
    author = "English, Sinead and Bonsall, Michael B",
    title = "Physiological dynamics, reproduction-maintenance allocations, and life history evolution.",
    year = "2019",
    journal = "Ecology and evolution",
    abstract = "Allocation of resources to competing processes of growth, maintenance, or reproduction is arguably a key process driving the physiology of life history trade-offs and has been shown to affect immune defenses, the evolution of aging, and the evolutionary ecology of offspring quality. Here, we develop a framework to investigate the evolutionary consequences of physiological dynamics by developing theory linking reproductive cell dynamics and components of fitness associated with costly resource allocation decisions to broader life history consequences. We scale these reproductive cell allocation decisions to population-level survival and fecundity using a life history approach and explore the effects of investment in reproduction or tissue-specific repair (somatic or reproductive) on the force of selection, reproductive effort, and resource allocation decisions. At the cellular level, we show that investment in protecting reproductive cells increases fitness when reproductive cell maturation rate is high or reproductive cell death is high. At the population level, life history fitness measures show that cellular protection increases reproductive value by differential investment in somatic or reproductive cells and the optimal allocation of resources to reproduction is moulded by this level of investment. Our model provides a framework to understand the evolutionary consequences of physiological processes underlying trade-offs and highlights the insights to be gained from considering fitness at multiple levels, from cell dynamics through to population growth.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC6706218/",
    doi = "10.1002/ece3.5477",
    pmcid = "PMC6706218",
    pmid = "31463023"
}

Summary Reproduction in wild animals can divert limited resources away from immune defence, resulting in increased parasite burdens. A longstanding prediction of life history theory states that these parasites can harm the reproductive individual, reducing its subsequent fitness and producing reproduction-fitness tradeoffs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent fitness in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation for downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life history tradeoffs, supporting the role of parasites as an important mediating factor in wild mammal populations.

@misc{doi101101683094,
    author = "Albery, Gregory F. and Morris, Alison and Morris, Seán and Kenyon, Fiona and Nussey, Daniel H. and Pemberton, Josephine M.",
    title = "Fitness costs of parasites explain multiple life history tradeoffs in a wild mammal",
    year = "2019",
    booktitle = "bioRxiv (Cold Spring Harbor Laboratory)",
    abstract = "Summary Reproduction in wild animals can divert limited resources away from immune defence, resulting in increased parasite burdens. A longstanding prediction of life history theory states that these parasites can harm the reproductive individual, reducing its subsequent fitness and producing reproduction-fitness tradeoffs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent fitness in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation for downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life history tradeoffs, supporting the role of parasites as an important mediating factor in wild mammal populations.",
    url = "https://doi.org/10.1101/683094",
    doi = "10.1101/683094",
    openalex = "W2955403558"
}

Reproduction in wild animals can divert limited resources away from immune defence, resulting in increased parasite burdens. A longstanding prediction of life history theory states that these parasites can harm the individual, reducing the organism’s subsequent fitness and producing reproduction-fitness tradeoffs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent fitness in a wild population of individually identified red deer ( Cervus elaphus ). Using path analysis, we investigated whether costs of lactation for downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life history tradeoffs, supporting the role of parasites as an important mediating factor in wild mammal populations.

@misc{albery2020fitness,
    author = "Albery, Gregory and Morris, Alison and Morris, Sean and Kenyon, Fiona and Nussey, Daniel H and Pemberton, Josephine M",
    title = "Fitness costs of parasites explain multiple life history tradeoffs in a wild mammal",
    year = "2020",
    publisher = "Dryad",
    abstract = "Reproduction in wild animals can divert limited resources away from immune
 defence, resulting in increased parasite burdens. A longstanding
 prediction of life history theory states that these parasites can harm the
 individual, reducing the organism’s subsequent fitness and producing
 reproduction-fitness tradeoffs. Here, we examined associations among
 reproductive allocation, immunity, parasitism, and subsequent fitness in a
 wild population of individually identified red deer ( Cervus elaphus ).
 Using path analysis, we investigated whether costs of lactation for
 downstream survival and fecundity were mediated by changes in strongyle
 nematode count and mucosal antibody levels. Lactating females exhibited
 increased parasite counts, which were in turn associated with
 substantially decreased fitness in the following year in terms of
 overwinter survival, fecundity, subsequent calf weight, and parturition
 date. This study offers observational evidence for parasite regulation of
 multiple life history tradeoffs, supporting the role of parasites as an
 important mediating factor in wild mammal populations.",
    url = "https://datadryad.org/dataset/doi:10.5061/dryad.n8pk0p2t7",
    doi = "10.5061/dryad.n8pk0p2t7"
}

The existence of a trade-off between current and future reproduction is a fundamental prediction of life history theory. Support for this prediction comes from brood size manipulations, showing that caring for enlarged broods often reduces the parent's future survival or fecundity. However, in many species, individuals must invest in competing for the resources required for future reproduction. Thus, a neglected aspect of this trade-off is that increased allocation to current reproduction may reduce an individual's future competitive ability. We tested this prediction in the burying beetle, Nicrophorus vespilloides, a species where parents care for their offspring and where there is fierce competition for resources used for breeding. We manipulated reproductive effort by providing females with either a small brood of 10 larvae or a large brood of 40 larvae and compared the ability of these females, and virgin females that had no prior access to a carcass, to compete for a second carcass against a virgin competitor. We found that increased allocation to current reproduction reduced future competitive ability, as females that had cared for a small brood were more successful when competing for a second carcass against a virgin competitor than females that had cared for a large brood. In addition, the costs of reproduction were offset by the benefits of feeding from the carcass during an initial breeding attempt, as females that had cared for a small brood were better competitors than virgin females that had no prior access to a carcass, whilst females that had cared for a large brood were similar in competitive ability to virgin females. Our results add to our understanding of the trade-off between current and future reproduction by showing that this trade-off can manifest through differences in future competitive ability and that direct benefits of reproduction can offset some of these costs.

@article{doi1011111365265613242,
    author = "Richardson, Jon and Stephens, Josh and Smiseth, Per T",
    title = "Increased allocation to reproduction reduces future competitive ability in a burying beetle.",
    year = "2020",
    journal = "The Journal of animal ecology",
    abstract = "The existence of a trade-off between current and future reproduction is a fundamental prediction of life history theory. Support for this prediction comes from brood size manipulations, showing that caring for enlarged broods often reduces the parent's future survival or fecundity. However, in many species, individuals must invest in competing for the resources required for future reproduction. Thus, a neglected aspect of this trade-off is that increased allocation to current reproduction may reduce an individual's future competitive ability. We tested this prediction in the burying beetle, Nicrophorus vespilloides, a species where parents care for their offspring and where there is fierce competition for resources used for breeding. We manipulated reproductive effort by providing females with either a small brood of 10 larvae or a large brood of 40 larvae and compared the ability of these females, and virgin females that had no prior access to a carcass, to compete for a second carcass against a virgin competitor. We found that increased allocation to current reproduction reduced future competitive ability, as females that had cared for a small brood were more successful when competing for a second carcass against a virgin competitor than females that had cared for a large brood. In addition, the costs of reproduction were offset by the benefits of feeding from the carcass during an initial breeding attempt, as females that had cared for a small brood were better competitors than virgin females that had no prior access to a carcass, whilst females that had cared for a large brood were similar in competitive ability to virgin females. Our results add to our understanding of the trade-off between current and future reproduction by showing that this trade-off can manifest through differences in future competitive ability and that direct benefits of reproduction can offset some of these costs.",
    url = "https://pubmed.ncbi.nlm.nih.gov/32356341/",
    doi = "10.1111/1365-2656.13242",
    pmid = "32356341"
}

AbstractReproduction in wild animals can divert limited resources away from immune defense, resulting in increased parasite burdens. A long-standing prediction of life-history theory states that these parasites can harm the reproductive individual, reducing its subsequent survival and fecundity, producing reproduction-fitness trade-offs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent survival and fecundity in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation in terms of downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life-history trade-offs, supporting the role of parasites as an important mediating factor in wild mammal populations.

@article{doi101086712633,
    author = "Albery, Gregory F and Morris, Alison and Morris, Sean and Kenyon, Fiona and Nussey, Daniel H and Pemberton, Josephine M",
    title = "Fitness Costs of Parasites Explain Multiple Life-History Trade-Offs in a Wild Mammal.",
    year = "2021",
    journal = "The American naturalist",
    abstract = "AbstractReproduction in wild animals can divert limited resources away from immune defense, resulting in increased parasite burdens. A long-standing prediction of life-history theory states that these parasites can harm the reproductive individual, reducing its subsequent survival and fecundity, producing reproduction-fitness trade-offs. Here, we examined associations among reproductive allocation, immunity, parasitism, and subsequent survival and fecundity in a wild population of individually identified red deer (Cervus elaphus). Using path analysis, we investigated whether costs of lactation in terms of downstream survival and fecundity were mediated by changes in strongyle nematode count and mucosal antibody levels. Lactating females exhibited increased parasite counts, which were in turn associated with substantially decreased fitness in the following year in terms of overwinter survival, fecundity, subsequent calf weight, and parturition date. This study offers observational evidence for parasite regulation of multiple life-history trade-offs, supporting the role of parasites as an important mediating factor in wild mammal populations.",
    url = "https://pubmed.ncbi.nlm.nih.gov/33625970/",
    doi = "10.1086/712633",
    pmid = "33625970"
}

Reproductive senescence is an age-associated decline in reproductive performance, which often arises as a trade-off between current and future reproduction. Given that mortality is inevitable, increased allocation into current reproduction is favoured despite costs paid later in life. This assumption is violated in organisms with post-maturity growth whose reproductive output increases long after maturity. While reproductive senescence is frequently studied in animals with determinate growth at maturity, such as insects or mammals, we have very limited understanding of reproductive senescence in organisms with an extensive post-maturity growth period. The fact that many post-maturity growers experience strong adult mortality leads to conflicting expectations for reproductive senescence. The aim of this study was to investigate how co-occurrence of rapid life history and post-maturity growth mould reproductive senescence in a short-lived killifish, Nothobranchius furzeri, using longitudinal data on laboratory and wild-type populations. We followed the individual fecundity, fertility and fertilization of 132 singly housed fish from the perspectives of chronological and biological age. At the onset of senescence, the sex-specific contribution to decrease in fertilization capacity was investigated. Allocation trade-offs were estimated through the association between reproductive parameters and life span, and between early-life and late-life fecundity. We demonstrate that female fecundity increased steadily after maturity and reproductive senescence occurred long after the growth asymptote. The prime age for fecundity coincided with 50% female survival and consequent decline in fecundity implies an association with somatic deterioration. Reproductive senescence in fertilization rate was stronger in females than in males. Females with high early fecundity experienced a long life span and high late-life fecundity, discounting the role of allocation trade-offs in reproductive senescence. The present study reports a clear case of reproductive senescence in a fish with a long post-maturation growth period, unusually rapid development and short life span. The onset of reproductive senescence was postponed compared to animals that cease growing at sexual maturity. Fish and other animals with post-maturity growth have long been considered insusceptible to ageing but this conclusion may be related to the previous lack of longitudinal data rather than to the absence of reproductive senescence in such organisms.

@article{doi1011111365265613382,
    author = "Žák, Jakub and Reichard, Martin",
    title = "Reproductive senescence in a short-lived fish.",
    year = "2021",
    journal = "The Journal of animal ecology",
    abstract = "Reproductive senescence is an age-associated decline in reproductive performance, which often arises as a trade-off between current and future reproduction. Given that mortality is inevitable, increased allocation into current reproduction is favoured despite costs paid later in life. This assumption is violated in organisms with post-maturity growth whose reproductive output increases long after maturity. While reproductive senescence is frequently studied in animals with determinate growth at maturity, such as insects or mammals, we have very limited understanding of reproductive senescence in organisms with an extensive post-maturity growth period. The fact that many post-maturity growers experience strong adult mortality leads to conflicting expectations for reproductive senescence. The aim of this study was to investigate how co-occurrence of rapid life history and post-maturity growth mould reproductive senescence in a short-lived killifish, Nothobranchius furzeri, using longitudinal data on laboratory and wild-type populations. We followed the individual fecundity, fertility and fertilization of 132 singly housed fish from the perspectives of chronological and biological age. At the onset of senescence, the sex-specific contribution to decrease in fertilization capacity was investigated. Allocation trade-offs were estimated through the association between reproductive parameters and life span, and between early-life and late-life fecundity. We demonstrate that female fecundity increased steadily after maturity and reproductive senescence occurred long after the growth asymptote. The prime age for fecundity coincided with 50\% female survival and consequent decline in fecundity implies an association with somatic deterioration. Reproductive senescence in fertilization rate was stronger in females than in males. Females with high early fecundity experienced a long life span and high late-life fecundity, discounting the role of allocation trade-offs in reproductive senescence. The present study reports a clear case of reproductive senescence in a fish with a long post-maturation growth period, unusually rapid development and short life span. The onset of reproductive senescence was postponed compared to animals that cease growing at sexual maturity. Fish and other animals with post-maturity growth have long been considered insusceptible to ageing but this conclusion may be related to the previous lack of longitudinal data rather than to the absence of reproductive senescence in such organisms.",
    url = "https://pubmed.ncbi.nlm.nih.gov/33159690/",
    doi = "10.1111/1365-2656.13382",
    pmid = "33159690"
}

Insects face the constant challenge of balancing energy allocation between reproduction and immune responses, both of which are highly energy-demanding processes. Immune challenges frequently result in decreased fecundity, reduced egg viability, and delayed ovarian development. Conversely, heightened reproductive activity often suppresses immune functions. This trade-off has profound ecological and evolutionary consequences, shaping insects' survival, adaptation, and population dynamics. The intricate interplay between reproduction and immunity in insects is regulated by the neuroendocrine and endocrine systems, which orchestrate resource distribution alongside other biological processes. Key hormones, such as juvenile hormone and ecdysteroids, serve as central regulators, influencing both immune responses and reproductive activities. Additionally, macromolecules like vitellogenin and lipophorin, primarily known for their functions as yolk protein precursors and lipid carriers, play crucial roles in pathogen recognition and transgenerational immune priming. Advancements in molecular and omics tools have unveiled the complexity of these regulatory mechanisms, providing new insights into how insects dynamically allocate resources to optimize their fitness. This delicate balance underscores critical evolutionary strategies and the integration of physiological systems across species. This review synthesizes insights from life history theory, oogenesis, and immunity, offering new perspectives on the trade-offs between reproductive output and immune investment.

@article{doi103390insects16030311,
    author = "Leyria, Jimena and Fruttero, Leonardo L and Paglione, Pedro A and Canavoso, Lilián E",
    title = "How Insects Balance Reproductive Output and Immune Investment.",
    year = "2025",
    journal = "Insects",
    abstract = "Insects face the constant challenge of balancing energy allocation between reproduction and immune responses, both of which are highly energy-demanding processes. Immune challenges frequently result in decreased fecundity, reduced egg viability, and delayed ovarian development. Conversely, heightened reproductive activity often suppresses immune functions. This trade-off has profound ecological and evolutionary consequences, shaping insects' survival, adaptation, and population dynamics. The intricate interplay between reproduction and immunity in insects is regulated by the neuroendocrine and endocrine systems, which orchestrate resource distribution alongside other biological processes. Key hormones, such as juvenile hormone and ecdysteroids, serve as central regulators, influencing both immune responses and reproductive activities. Additionally, macromolecules like vitellogenin and lipophorin, primarily known for their functions as yolk protein precursors and lipid carriers, play crucial roles in pathogen recognition and transgenerational immune priming. Advancements in molecular and omics tools have unveiled the complexity of these regulatory mechanisms, providing new insights into how insects dynamically allocate resources to optimize their fitness. This delicate balance underscores critical evolutionary strategies and the integration of physiological systems across species. This review synthesizes insights from life history theory, oogenesis, and immunity, offering new perspectives on the trade-offs between reproductive output and immune investment.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC11943238/",
    doi = "10.3390/insects16030311",
    pmcid = "PMC11943238",
    pmid = "40266843"
}

Understanding how organisms allocate resources between self-maintenance and reproduction in response to infection is central to life-history evolution. Maternal transfer of immune protection to offspring, often referred to as transgenerational immune priming (TGIP), represents a potentially important component of reproductive allocation. However, the extent to which this maternal effect varies genetically and covaries with other life-history traits remains poorly understood. Here, we investigated genetic variation in maternal transfer of immune protection and its association with key life-history traits in the mealworm beetle Tenebrio molitor. Using ten inbred lines, we quantified maternal body mass, fecundity, investment in offspring immune protection, and survival under starvation following a bacterial immune challenge. This design allowed us to estimate the broad-sense heritability of maternal immune transfer in an invertebrate and to assess genetic correlations with other traits. We found significant genetic variation in maternal immune transfer, fecundity, and body mass. Investment in offspring immune protection was positively correlated with fecundity but negatively correlated with body mass, while its association with survival was negative but not statistically significant. Smaller females provided more immune protection to their offspring but produced fewer offspring, suggesting a potential trade-off between reproductive effort and offspring immunity depending on body size. Overall, our results suggest that maternal transfer of immune protection in T. molitor is an evolvable trait that is integrated with broader life-history variation. More broadly, this study highlights the importance of considering maternal immune effects as an integrated component of reproductive allocation, potentially shaping adaptive immune investment within species.

@article{doi101038s41437026008509,
    author = "Dhinaut, Julien and Chogne, Manon and Sabarly, Camille and Balourdet, Aude and Develay, Charlène and Teixeira, Maria and Debrosse, Nelly and Crosland, Agathe and Rigaud, Thierry and Moret, Yannick",
    title = "Genetic variation in transgenerational immune priming and its association with fecundity and body mass in the mealworm beetle Tenebrio molitor.",
    year = "2026",
    journal = "Heredity",
    abstract = "Understanding how organisms allocate resources between self-maintenance and reproduction in response to infection is central to life-history evolution. Maternal transfer of immune protection to offspring, often referred to as transgenerational immune priming (TGIP), represents a potentially important component of reproductive allocation. However, the extent to which this maternal effect varies genetically and covaries with other life-history traits remains poorly understood. Here, we investigated genetic variation in maternal transfer of immune protection and its association with key life-history traits in the mealworm beetle Tenebrio molitor. Using ten inbred lines, we quantified maternal body mass, fecundity, investment in offspring immune protection, and survival under starvation following a bacterial immune challenge. This design allowed us to estimate the broad-sense heritability of maternal immune transfer in an invertebrate and to assess genetic correlations with other traits. We found significant genetic variation in maternal immune transfer, fecundity, and body mass. Investment in offspring immune protection was positively correlated with fecundity but negatively correlated with body mass, while its association with survival was negative but not statistically significant. Smaller females provided more immune protection to their offspring but produced fewer offspring, suggesting a potential trade-off between reproductive effort and offspring immunity depending on body size. Overall, our results suggest that maternal transfer of immune protection in T. molitor is an evolvable trait that is integrated with broader life-history variation. More broadly, this study highlights the importance of considering maternal immune effects as an integrated component of reproductive allocation, potentially shaping adaptive immune investment within species.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/10785379/",
    doi = "10.1038/s41437-026-00850-9",
    pmcid = "10785379",
    pmid = "42209763"
}

Coreius guichenoti, an endemic fish of the upper Yangtze River, has experienced severe population decline due to overfishing and habitat fragmentation. To inform its conservation, this study compared life-history traits between artificially bred and historical wild populations, revealing pronounced plasticity in response to environmental conditions. The cultured population, dominated by age 0-4 individuals but retaining a notable proportion of age 5-6 fish, exhibited faster growth and higher fecundity (mean absolute fecundity 32,724 ± 24,132 eggs; relative fecundity 37.5 ± 18.5 eggs/g) than the wild population. In contrast, the wild group consisted of >90% age 0-4 individuals, showed virtually no fish aged 5-7, reproduced seasonally with high total egg output, and tended toward a periodic life-history strategy, whereas the cultured group tended toward an opportunistic strategy that still retained some periodic traits. These results demonstrate that C. guichenoti can adjust its life history on a within-generation scale. Accordingly, we recommend pre-release conditioning with moderate flow and temperature variations to enhance field adaptability. This study provides evidence-based guidance for broodstock selection and preconditioning in restocking programs, aimed at improving post-release survival and reproductive success in the wild.

@article{doi103390ani16030456,
    author = "Xiang, Miao and Liu, Haoran and Meng, Zihao and Zhao, Yan and Yin, Chengjie and Li, Xuemei and Wu, Xingbing and Zhu, Tingbing",
    title = "Life-History Plasticity of Cultured Coreius guichenoti: Energy Allocation Trade-Offs and Conservation Applications.",
    year = "2026",
    journal = "Animals: an open access journal from MDPI",
    abstract = "Coreius guichenoti, an endemic fish of the upper Yangtze River, has experienced severe population decline due to overfishing and habitat fragmentation. To inform its conservation, this study compared life-history traits between artificially bred and historical wild populations, revealing pronounced plasticity in response to environmental conditions. The cultured population, dominated by age 0-4 individuals but retaining a notable proportion of age 5-6 fish, exhibited faster growth and higher fecundity (mean absolute fecundity 32,724 ± 24,132 eggs; relative fecundity 37.5 ± 18.5 eggs/g) than the wild population. In contrast, the wild group consisted of >90\% age 0-4 individuals, showed virtually no fish aged 5-7, reproduced seasonally with high total egg output, and tended toward a periodic life-history strategy, whereas the cultured group tended toward an opportunistic strategy that still retained some periodic traits. These results demonstrate that C. guichenoti can adjust its life history on a within-generation scale. Accordingly, we recommend pre-release conditioning with moderate flow and temperature variations to enhance field adaptability. This study provides evidence-based guidance for broodstock selection and preconditioning in restocking programs, aimed at improving post-release survival and reproductive success in the wild.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC12896735/",
    doi = "10.3390/ani16030456",
    pmcid = "PMC12896735",
    pmid = "41681442"
}