scholarly journals Life history adaptations to fluctuating environments: Combined effects of demographic buffering and lability of vital rates

2021 ◽  
Author(s):  
Christie Le Coeur ◽  
Nigel Gilles Yoccoz ◽  
Roberto Salguero-Gomez ◽  
Yngvild Vindenes
Keyword(s):  
Life History ◽  
Life Histories ◽  
Environmental Variability ◽  
Stochastic Simulations ◽  
Relative Fitness ◽  
Vital Rates ◽  
Matrix Population Models ◽  
Negative Effects ◽  
Variable Environments ◽  
Living Species

Demographic buffering and lability have both been identified as important adaptive strategies to optimise long-term fitness in variable environments. These strategies are not mutually exclusive, however we lack efficient methods to measure their relative importance. Here, we define a new index to measure the total lability for a given life history, and use stochastic simulations to disentangle relative fitness effects of buffering and lability. The simulations use 81 animal matrix population models, and different scenarios to explore how the strategies vary across life histories. The highest potential for adaptive demographic lability was found for short- to intermediately long-lived species, while demographic buffering was the main response in slow-living species. This study suggests that faster-living species are more responsive to environmental variability, both for positive or negative effects. Our methods and results provide a more comprehensive view of adaptations to variability, of high relevance to predict species responses to climate change.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

scholarly journals From stochastic environments to life histories and back

2009 ◽  
Vol 364 (1523) ◽  
pp. 1499-1509 ◽  
Author(s):  
Shripad Tuljapurkar ◽  
Jean-Michel Gaillard ◽  
Tim Coulson
Keyword(s):  
Life History ◽  
Growth Rates ◽  
Life Histories ◽  
Life History Evolution ◽  
Environmental Stochasticity ◽  
Vital Rates ◽  
Stochastic Growth ◽  
Individual Fitness ◽  
History Evolution ◽  
Average Individual

Environmental stochasticity is known to play an important role in life-history evolution, but most general theory assumes a constant environment. In this paper, we examine life-history evolution in a variable environment, by decomposing average individual fitness (measured by the long-run stochastic growth rate) into contributions from average vital rates and their temporal variation. We examine how generation time, demographic dispersion (measured by the dispersion of reproductive events across the lifespan), demographic resilience (measured by damping time), within-year variances in vital rates, within-year correlations between vital rates and between-year correlations in vital rates combine to determine average individual fitness of stylized life histories. In a fluctuating environment, we show that there is often a range of cohort generation times at which the fitness is at a maximum. Thus, we expect ‘optimal’ phenotypes in fluctuating environments to differ from optimal phenotypes in constant environments. We show that stochastic growth rates are strongly affected by demographic dispersion, even when deterministic growth rates are not, and that demographic dispersion also determines the response of life-history-specific average fitness to within- and between-year correlations. Serial correlations can have a strong effect on fitness, and, depending on the structure of the life history, may act to increase or decrease fitness. The approach we outline takes a useful first step in developing general life-history theory for non-constant environments.

scholarly journals The importance of life history and population regulation for the evolution of social learning

2020 ◽  
Vol 375 (1803) ◽  
pp. 20190492 ◽  
Author(s):  
Dominik Deffner ◽  
Richard McElreath
Keyword(s):  
Life History ◽  
Social Learning ◽  
Age Structure ◽  
Life Histories ◽  
Population Regulation ◽  
Individual Learning ◽  
Vital Rates ◽  
Strategic Learning ◽  
Cognition And Culture ◽  
Exemplary Model

Social learning and life history interact in human adaptation, but nearly all models of the evolution of social learning omit age structure and population regulation. Further progress is hindered by a poor appreciation of how life history affects selection on learning. We discuss why life history and age structure are important for social learning and present an exemplary model of the evolution of social learning in which demographic properties of the population arise endogenously from assumptions about per capita vital rates and different forms of population regulation. We find that, counterintuitively, a stronger reliance on social learning is favoured in organisms characterized by ‘fast’ life histories with high mortality and fertility rates compared to ‘slower’ life histories typical of primates. Long lifespans make early investment in learning more profitable and increase the probability that the environment switches within generations. Both effects favour more individual learning. Additionally, under fertility regulation (as opposed to mortality regulation), more juveniles are born shortly after switches in the environment when many adults are not adapted, creating selection for more individual learning. To explain the empirical association between social learning and long life spans and to appreciate the implications for human evolution, we need further modelling frameworks allowing strategic learning and cumulative culture. This article is part of the theme issue ‘Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals’.

scholarly journals Between semelparity and iteroparity: empirical evidence for a continuum of modes of parity

2017 ◽  
Author(s):  
P. William Hughes
Keyword(s):  
Life History ◽  
Mathematical Models ◽  
Molecular Basis ◽  
Life Histories ◽  
Life History Theory ◽  
Reproductive Effort ◽  
Theoretical Biology ◽  
Relative Fitness ◽  
Life History Strategies ◽  
Molecular Evidence

ABSTRACTThe number of times an organism reproduces (i.e. its mode of parity) is a fundamental life-history character, and evolutionary and ecological models that compare the relative fitness of strategies are common in life history theory and theoretical biology. Despite the success of mathematical models designed to compare intrinsic rates of increase between annual-semelparous and perennial-iteroparous reproductive schedules, there is widespread evidence that variation in reproductive allocation among semelparous and iteroparous organisms alike is continuous. This paper reviews the ecological and molecular evidence for the continuity and plasticity of modes of parity––that is, the idea that annual-semelparous and perennial-iteroparous life histories are better understood as endpoints along a continuum of possible strategies. I conclude that parity should be understood as a continuum of different modes of parity, which differ by the degree to which they disperse or concentrate reproductive effort in time. I further argue that there are three main implications of this conclusion: (1) That seasonality should not be conflated with parity; (2) that mathematical models purporting to explain the evolution of semelparous life histories from iteroparous ones (or vice versa) should not assume that organisms can only display either an annual-semelparous life history or a perennial-iteroparous one; and (3) that evolutionary ecologists should examine the physiological or molecular basis of traits underlying different modes of parity, in order to obtain a general understanding of how different life history strategies can evolve from one another.

The persistence niche: what makes it and what breaks it for two fire-prone plant species

2007 ◽  
Vol 55 (3) ◽  
pp. 273 ◽  
Author(s):  
David A. Keith ◽  
Mark G. Tozer ◽  
Tracey J. Regan ◽  
Helen M. Regan
Keyword(s):  
Life History ◽  
Seed Production ◽  
Life Histories ◽  
Phytophthora Cinnamomi ◽  
Population Viability ◽  
Vital Rates ◽  
High Fecundity ◽  
In Fire ◽  
Rates Of Growth ◽  
Regeneration Niches

Persistence niches are expected to favour qualitatively different plant life histories compared with regeneration niches. In fire-prone habitats, for example, resprouting plants may be expected to exploit persistence niches, whereas obligate-seeders by definition exploit regeneration niches. Resprouter life histories should be typified by high rates of survival, which may be offset by relatively low rates of growth and reproduction. This combination of characters is expected to result from trade-offs in resource allocation and because the longevity of individual plants should buffer their populations against the effects of recruitment failure. We asked whether two resprouting perennial shrubs, Epacris barbata Melville and Xanthorrhoea resinifera (Sol. Ex Kite) E.C.Nelson & D.J.Bedford, exhibited the life-history character combinations that are expected for species exploiting a persistence niche. We also investigated how a change in habitat suitability caused by the invasion of a root pathogen may limit the ability of these species to occupy persistence niches. Demographic censuses of several years’ duration in two populations of each species yielded estimates of vital rates that were consistent with the life-history profile expected for a persistence niche. Rates of background survival were high and rates of fire-related mortality were low in both species. As expected, these were associated with low rates of growth and seedling establishment, although rates of seed production and viability were relatively high in both species. The importance of survival was confirmed by stochastic population models, which showed that population viability was more sensitive to decreases in survival of mature plants and increases in fire mortality of established plants than to changes in other vital rates. Seedling growth rates were also relatively important in E. barbata. Populations of both species that had been infected by root rot disease, Phytophthora cinnamomi, had substantially reduced survival rates and, consequently, reduced population viability. These effects were more extreme in E. barbata than in X. resinifera. We conclude that processes that reduce survival, such as disease infection and habitat loss, rather than processes that impede seed production and recruitment mediate the persistence niche. However, we discuss the possibility that this dependency might be mitigated by high fecundity if infrequent conditions that permit large recruitment events have so far eluded detection.

A new conceptual framework for evaluating the early ontogeny phase of recruitment processes among marine fish species

2012 ◽  
Vol 69 (12) ◽  
pp. 2112-2129 ◽  
Author(s):  
Miriam J. Doyle ◽  
Kathryn L. Mier
Keyword(s):  
Life History ◽  
Conceptual Framework ◽  
Early Life ◽  
Life Histories ◽  
Environmental Variability ◽  
Principal Component ◽  
Early Life History ◽  
Environmental Forcing ◽  
Ongoing Research ◽  
Trade Offs

For Gulf of Alaska (GOA) fish populations, ordination by principal component analysis of a matrix of species by early life history and ecological traits resulted in distribution of species along three primary gradients. These are synonymous with phenology of egg and larval production, quantity of production, and ubiquity of larvae, the latter representing temporal and spatial extent of distribution in the pelagic environment. GOA species were assigned to categories that shared similar positions in ordination space relative to the three primary gradients. From this comparative analysis, a conceptual framework is proposed for species’ early life histories representing trade-offs in adaptation to prevailing environmental conditions and associated vulnerability and resilience factors that may modulate species’ recruitment responses to environmental variability. The utility of this framework for evaluating response to environmental forcing was supported by the analysis of a 27-year time series of GOA late spring larval fish abundance. The hypothesis for this ongoing research is that we can utilize similarities in reproductive and early life history characteristics among species to identify (i) ecologically determined species groups that are predisposed to respond to environmental forcing in similar ways and (ii) plausible environmental predictors of recruitment variation attributable to aspects of early life history.

scholarly journals Rcompadre and Rage - two R packages to facilitate the use of the COMPADRE and COMADRE databases and calculation of life history traits from matrix population models

2021 ◽  
Author(s):  
Owen R Jones ◽  
Patrick Barks ◽  
Iain M Stott ◽  
Tamora D James ◽  
Sam C. Levin ◽  
...  
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Geographic Location ◽  
Time Frame ◽  
Life Cycles ◽  
Population Models ◽  
Vital Rates ◽  
Matrix Population Models ◽  
History Of ◽  
R Packages

Matrix population models (MPMs) are an important tool in the arsenal of biologists seeking to understand the causes and consequences of variation in vital rates (e.g. survival, reproduction) across life cycles. MPMs describe the age- or stage-structured demography of organisms and represent the life history of a population during a particular time frame at a specific geographic location. The COMPADRE Plant Matrix Database and COMADRE Animal Matrix Database are the most extensive resources for MPM data, collectively containing >12,000 MPMs for >1,100 species globally. Although these databases represent an unparalleled resource for researchers, land managers, and educators, the current computational tools available to answer questions with MPMs impose significant barriers to potential users by requiring advanced knowledge to handle diverse data structures and program custom analysis functions. To close this knowledge gap, we present two R packages designed to (i) facilitate the use of these databases by providing functions to acquire, check, and manage the MPM data contained in COMPADRE and COMADRE (Rcompadre), and (ii) expand the range of life history traits that can be calculated from MPMs in support of ecological and evolutionary analyses (Rage). We provide vignettes to illustrate the use of both Rcompadre and Rage. Rcompadre and Rage will facilitate demographic analyses using MPM data and contribute to the improved replicability of studies using these data. We hope that this new functionality will allow researchers, land managers, and educators to unlock the potential behind the thousands of MPMs and ancillary metadata stored in the COMPADRE and COMADRE matrix databases.

scholarly journals Unusually Paced Life History Strategies of Marine Megafauna Drive Atypical Sensitivities to Environmental Variability

2020 ◽  
Vol 7 ◽  
Author(s):  
Isabel M. Smallegange ◽  
Marta Flotats Avilés ◽  
Kim Eustache
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
Life Histories ◽  
Life History Traits ◽  
Environmental Variability ◽  
Life History Strategies ◽  
Marine Biodiversity ◽  
Juvenile Mortality ◽  
Population Responses ◽  
Marine Megafauna

Understanding why different life history strategies respond differently to changes in environmental variability is necessary to be able to predict eco-evolutionary population responses to change. Marine megafauna display unusual combinations of life history traits. For example, rays, sharks and turtles are all long-lived, characteristic of slow life histories. However, turtles also have very high reproduction rates and juvenile mortality, characteristic of fast life histories. Sharks and rays, in contrast, produce a few live-born young, which have low mortality rates, characteristic of slow life histories. This raises the question if marine megafaunal responses to environmental variability follow conventional life history patterns, including the pattern that fast life histories are more sensitive to environmental autocorrelation than slow life histories. To answer this question, we used a functional trait approach to quantify for different species of mobulid rays, cheloniid sea turtles and carcharhinid sharks – all inhabitants or visitors of (human-dominated) coastalscapes – how their life history, average size and log stochastic population growth rate, log(λs), respond to changes in environmental autocorrelation and in the frequency of favorable environmental conditions. The faster life histories were more sensitive to temporal frequency of favourable environmental conditions, but both faster and slower life histories were equally sensitive, although of opposite sign, to environmental autocorrelation. These patterns are atypical, likely following from the unusual life history traits that the megafauna display, as responses were linked to variation in mortality, growth and reproduction rates. Our findings signify the importance of understanding how life history traits and population responses to environmental change are linked. Such understanding is a basis for accurate predictions of marine megafauna population responses to environmental perturbations like (over)fishing, and to shifts in the autocorrelation of environmental variables, ultimately contributing toward bending the curve on marine biodiversity loss.

scholarly journals Harsh environments and "fast" human life histories: What does the theory say?

2015 ◽  
Author(s):  
Ryan Baldini
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Environmental Changes ◽  
Human Life ◽  
Life History Evolution ◽  
Harsh Environments ◽  
Harsh Environment ◽  
Common Belief ◽  
Vital Rates

A common belief among human life history researchers is that "harsher" environments - i.e., those with higher mortality rates and resource stress - select for "fast" life histories, i.e. earlier reproduction and faster senescence. I show that these "harsh environments, fast life histories" - or HEFLH - hypotheses are poorly supported by evolutionary theory. First, I use a simple model to show that effects of environmental harshness on life history evolution are incredibly diverse. In particular, small changes in basic but poorly understood variables - e.g., whether and how population density affects vital rates - can cause selection to favor very different life histories. Furthermore, I show that almost all life history theory used to justify HEFLH hypotheses is misapplied in the first place. The reason is that HEFLH hypotheses usually treat plastic responses to heterogeneous environmental conditions within a population, whereas the theory used to justify such hypotheses treat genetic responses to environmental changes across an entire population. Counter-intuitively, the predictions of the former do not generally apply to the latter: the optimal response to a harsh environment within a large heterogeneous environment is not necessarily the optimal strategy of a population uniformly inhabiting the same harsh environment. I discuss these theoretical results in light of the current state of empirical research.

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