Individual heterogeneity in life‐history trade‐offs with age at first reproduction in capital breeding elephant seals

AbstractThe 1-m-tall dwarf elephant Palaeoloxodon falconeri from the Pleistocene of Sicily (Italy) is an extreme example of insular dwarfism and epitomizes the Island Rule. Based on scaling of life-history (LH) traits with body mass, P. falconeri is widely considered to be ‘r-selected’ by truncation of the growth period, associated with an early onset of reproduction and an abbreviated lifespan. These conjectures are, however, at odds with predictions from LH models for adaptive shifts in body size on islands. To settle the LH strategy of P. falconeri, we used bone, molar, and tusk histology to infer growth rates, age at first reproduction, and longevity. Our results from all approaches are congruent and provide evidence that the insular dwarf elephant grew at very slow rates over an extended period; attained maturity at the age of 15 years; and had a minimum lifespan of 68 years. This surpasses not only the values predicted from body mass but even those of both its giant sister taxon (P. antiquus) and its large mainland cousin (L. africana). The suite of LH traits of P. falconeri is consistent with the LH data hitherto inferred for other dwarfed insular mammals. P. falconeri, thus, not only epitomizes the Island Rule but it can also be viewed as a paradigm of evolutionary change towards a slow LH that accompanies the process of dwarfing in insular mammals.

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The Evolution of Life History Parameters in Teleosts

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f84-114 ◽

1984 ◽

Vol 41 (6) ◽

pp. 989-1000 ◽

Cited By ~ 253

Author(s):

Derek A. Roff

Keyword(s):

Growth Rate ◽

Life History ◽

Life History Theory ◽

Larval Survival ◽

Reasonable Assumption ◽

Natural Mortality ◽

Age At First Reproduction ◽

Life History Parameters ◽

First Case ◽

First Reproduction

Empirical studies have shown that in teleosts there is a significant correlation between the life history parameters, age at first reproduction, natural mortality, and growth rate. In this paper 1 hypothesize that these correlations are the result of evolutionary adjustments due to the trade-off between reproduction, growth, and survival. A simple and reasonable assumption is that the costs of reproduction are sufficient to cause the ltmt function to decrease. A simple expression relating the age at first reproduction is derived from this assumption. This formula accounts for a statistically significant portion (60.6%) of the variation in age at first reproduction in 30 stocks of fish. To extend the model to predict the distribution of life history parameters across all teleosts, an explicit cost function is incorporated. The model is analyzed with respect to two fitness measures, the expected lifetime fecundity and malthusian parameter, r. In the first case it is shown that the optimal age at maturity, T, depends only on the natural mortality rate (M) and the growth rate (k). In the second case, T is a function of k and the logarithm of a parameter, In C; the latter is a product of egg and larval survival, maximum body length (Lx), and the proportionality coefficient of the fecundity/length function. Difficulties of measuring egg and larval survival make the testing of the latter case difficult for particular species. However, this method provides a simple formula for the computation of r; this is shown generally to be approximately zero, thereby adding strength to the assumptions of the first analysis. The distribution patterns of T on k and M on k are predicted and compared with the observed pattern. In general, the predictions are validated: however, certain combinations of k and ln C are shown to occur very infrequently. The prediction of such "empty" regions of the parameter space remains a challenge for future development of life history theory.

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Trade-off between age of first reproduction and survival in a female primate

Biology Letters ◽

10.1098/rsbl.2009.0009 ◽

2009 ◽

Vol 5 (3) ◽

pp. 339-342 ◽

Cited By ~ 53

Author(s):

Gregory E. Blomquist

Keyword(s):

Life History ◽

Life History Theory ◽

Rhesus Macaques ◽

Human Study ◽

Genetic Correlations ◽

Adult Survival ◽

Trade Off ◽

Trade Offs ◽

Female Life History ◽

First Reproduction

Trade-offs are central to life-history theory but difficult to document. Patterns of phenotypic and genetic correlations in rhesus macaques, Macaca mulatta —a long-lived, slow-reproducing primate—are used to test for a trade-off between female age of first reproduction and adult survival. A strong positive genetic correlation indicates that female macaques suffer reduced adult survival when they mature relatively early and implies primate senescence can be explained, in part, by antagonistic pleiotropy. Contrasts with a similar human study implicate the extension of parental effects to later ages as a potential mechanism for circumventing female life-history trade-offs in human evolution.

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Effects of non-toxic filamentous cyanobacteria isolated from tri an reservoir on Daphnia

ACADEMIA JOURNAL OF BIOLOGY ◽

10.15625/2615-9023/v42n3.13900 ◽

2020 ◽

Vol 42 (3) ◽

Author(s):

Pham Thanh Luu ◽

Tran Thi Hoang Yen ◽

Tran Thanh Thai ◽

Ngo Xuan Quang ◽

Hoang Nghia Son

Keyword(s):

High Performance Liquid Chromatography ◽

Life History ◽

Liquid Chromatography ◽

Secondary Metabolites ◽

High Performance ◽

Toxic Effects ◽

Filamentous Cyanobacteria ◽

Age At First Reproduction ◽

Bioactive Secondary Metabolites ◽

First Reproduction

This study is aimed to examine whether the presence of non-toxic ﬁlamentous cyanobacteria can cause toxic effects on Daphnia magna. Six strains of Oscillatoria perornata were isolated from the Tri An Reservoir and cultured in our laboratory for investigation. The results revealed that all strains were negative with the mcyA moleculer marker. The high performance liquid chromatography (HPLC) results showed that toxin was not detected in their culture products, indicating that these strains corresponded to non-toxin producing strains. However, the results of chronic assay indicated that these non-toxin producing O. perornata conferred toxic effects on the tested animals. The age at first reproduction of D. magna was delayed and the survival of D. manga decreased in proportional with the increase of the density of cells of O. perornata exposed. Significant differences in the life history responses were observed for D. mangna exposed to O. perornata. These results suggested that bioactive secondary metabolites other than microcystins produced by the filamentous cyanobacteria O. perornata may contribute to the toxic effects on Daphnia. Besides cyanotoxins, other secondary metabolites must be taken into account when investigating the toxic effects of cyanobacteria.

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Life history at the age at first reproduction

Ethology and Sociobiology ◽

10.1016/0162-3095(94)90027-2 ◽

1994 ◽

Vol 15 (1) ◽

pp. 55

Author(s):

Kim Hill

Keyword(s):

Life History ◽

Age At First Reproduction ◽

First Reproduction

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Carex secalina (Cyperaceae), a species critically endangered in Europe: from propagule germination to propagule production

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.2005.019 ◽

2011 ◽

Vol 74 (2) ◽

pp. 141-147 ◽

Cited By ~ 6

Author(s):

Waldemar Żukowski ◽

Marlena Lembicz ◽

Paweł Olejniczak ◽

Agnieszka Bogdanowicz ◽

Julian Chmiel

Keyword(s):

Life History ◽

Small Area ◽

Critically Endangered ◽

Age At First Reproduction ◽

The Third ◽

Germination Ability ◽

First Reproduction ◽

History Of ◽

Selected Traits ◽

And Bisexual

The size and reproduction ability of the three field populations of <em>Carex secalina</em> Willd. ex Wahlenb. have been assessed. In the parallel garden study selected traits from the life history of the species have been studied, such as age at first reproduction, fertility, the size of seeds, their germination ability and size of seedlings. The populations of <em>C. secalina</em> discovered in Poland in 2000 are characterised by small abundance and small area. All individuals from the three populations in the garden produced generative shoots in the third year of life. Statistically significant differences between the populations were found in the production of shoots with unisexual spikes and bisexual ones, the latter had not been reported in the hitherto literature on the species. The seeds started germinating after a 6-months rest. The first seedlings were observed in the first decade of May. The largest seedlings were noted in the population producing the smallest seeds. The results contribute to explaining the renewal of the populations of this species in the field.

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Age at first reproduction in wolves: different patterns of density dependence for females and males

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2021.0207 ◽

2021 ◽

Vol 288 (1948) ◽

Author(s):

Camilla Wikenros ◽

Morgane Gicquel ◽

Barbara Zimmermann ◽

Øystein Flagstad ◽

Mikael Åkesson

Keyword(s):

Life History ◽

Population Size ◽

Life History Trait ◽

Parameter Estimates ◽

Age At First Reproduction ◽

Illegal Hunting ◽

Reproductive Experience ◽

First Reproduction ◽

Pup Survival ◽

Benefits And Costs

Age at first reproduction constitutes a key life-history trait in animals and is evolutionarily shaped by fitness benefits and costs of delayed versus early reproduction. The understanding of how intrinsic and extrinsic changes affects age at first reproduction is crucial for conservation and management of threatened species because of its demographic effects on population growth and generation time. For a period of 40 years in the Scandinavian wolf ( Canis lupus ) population, including the recolonization phase, we estimated age at first successful reproduction (pup survival to at least three weeks of age) and examined how the variation among individuals was explained by sex, population size (from 1 to 74 packs), primiparous or multiparous origin, reproductive experience of the partner and inbreeding. Median age at first reproduction was 3 years for females ( n = 60) and 2 years for males ( n = 74), and ranged between 1 and 8–10 years of age ( n = 297). Female age at first reproduction decreased with increasing population size, and increased with higher levels of inbreeding. The probability for males to reproduce later first decreased, reaching its minimum when the number of territories approached 40–60, and then increased with increasing population size. Inbreeding for males and reproductive experience of parents and partners for both sexes had overall weak effects on age at first reproduction. These results allow for more accurate parameter estimates when modelling population dynamics for management and conservation of small and vulnerable wolf populations, and show how humans through legal harvest and illegal hunting influence an important life-history trait like age at first reproduction.

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

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.0220 ◽

2012 ◽

Vol 279 (1740) ◽

pp. 2998-3002 ◽

Cited By ~ 28

Author(s):

David Waynforth

Keyword(s):

Life History ◽

Chronic Disease ◽

Life Expectancy ◽

Life History Theory ◽

Pubertal Development ◽

Experimental Studies ◽

Past Research ◽

Theoretical Models ◽

Age At First Reproduction ◽

First Reproduction

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

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Individual heterogeneity in fitness in a long-lived herbivore

10.22541/au.162187024.48028698/v1 ◽

2021 ◽

Author(s):

Madeleine Lohman ◽

Thomas Riecke ◽

Perry Williams ◽

James Sedinger

Keyword(s):

Life History ◽

Clutch Size ◽

Environmental Conditions ◽

Energy Allocation ◽

Individual Heterogeneity ◽

Reproductive Value ◽

Posterior Mean ◽

Black Brant ◽

Trade Offs ◽

Breeding Probability

Heterogeneity in the intrinsic quality and nutritional condition of individuals affects reproductive success and consequently fitness. Understanding differences in energy allocation towards survival and reproduction within and among years might help explain variability in individual fitness. Black brant (Branta bernicla nigricans) are long-lived, migratory, specialist herbivores. Long migratory pathways and short summer breeding seasons constrain the time and energy available for reproduction, thus magnifying life-history trade-offs. These constraints, combined with long lifespans and trade-offs between current and future reproductive value, provide a model system to examine the role of individual heterogeneity in driving life-history strategies and individual heterogeneity in fitness. We used hierarchical Bayesian models to examine reproductive trade-offs, modeling the relationships between within-year measures of reproductive energy allocation and among-year demographic rates of individual females breeding on the Yukon-Kuskokwim Delta, Alaska using capture-recapture and reproductive data from 1988 to 2014. We provide evidence for relationships between breeding probability and clutch size (posterior mean of β = 0.45, 95% CRI = 0.33 – 0.57, SD = 0.06), breeding probability and nest initiation date (posterior mean of β = -0.12, 95% CRI = -0.2 ¬– -0.04, SD = 0.04), and an interaction between clutch size and initiation date (posterior mean of β = -0.12, 95% CRI = -0.2 – -0.04, SD = 0.04). Average lifetime clutch size also had a weak positive relationship with survival probability (posterior mean of β = 0.03, 95% CRI = -0.01 – 0.7, SD = 0.02). Our results support the use of demographic buffering strategies for black brant; reductions in reproductive energy allocation preserve high adult survival rates during years with poor environmental conditions, maximizing future reproductive value. We also indirectly show links among environmental conditions during growth, fitness, and energy allocation, highlighting the effects of early growth conditions on individual heterogeneity, and subsequently, reproductive investment.

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Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits

10.32942/osf.io/t9cvp ◽

2019 ◽

Author(s):

Jessica A. Haines ◽

Sarah E. Nason ◽

Alyshia M. M. Skurdal ◽

Tenal Bourchier ◽

Stan Boutin ◽

...

Keyword(s):

Life History ◽

Personality Traits ◽

Life History Traits ◽

Positive Association ◽

Activity Levels ◽

Life History Variation ◽

Red Squirrels ◽

Age At First Reproduction ◽

Pace Of Life ◽

First Reproduction

The pace of life syndrome hypothesis posits that personality traits (i.e., consistent individual differences in behaviour) are linked to life history and fitness. Specifically, fast-paced individuals are predicted to be proactive (i.e., active and aggressive) with an earlier age at first reproduction, a shorter lifespan, and a higher fecundity than slow-paced individuals. Environmental conditions and sex differences may be important in maintaining behavioural and life history variation in populations and may influence the covariance of personality with life history or lifetime fitness. However, these effects are rarely tested together. We investigated whether the occurrence of a resource pulse (called a mast year) during adulthood altered the associations between personality and life history traits or lifetime offspring production in adult North American red squirrels (Tamiasciurus hudsonicus). Despite accounting for environmental context during adulthood, we found no evidence of an overall pace-of-life syndrome in this population as personality was not associated with age at first reproduction or longevity in either sex. Males and females had similar activity levels, but females were more aggressive, potentially due to the fitness benefits of protecting their offspring from predation. In all females regardless of mast experience, there was no association between activity and lifetime pup production but there was a positive association between aggression and lifetime pup production. In males that experienced a mast there was a positive association between lifetime pup production and both activity and aggression. In males that did not experience a mast, there was no association between activity and lifetime pup production but a negative association between aggression and lifetime pup production. Lifetime recruit production in either sex was not influenced by activity or aggression regardless of mast experience. Overall, our results suggest that the infrequent occurrence of mast years may contribute to maintaining variation in personality traits in red squirrels.

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