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Bliard L, Martin JS, Paniw M, Blumstein DT, Martin JGA, Pemberton JM, Nussey DH, Childs DZ, Ozgul A. Detecting context dependence in the expression of life history trade-offs. J Anim Ecol 2024. [PMID: 39221784 DOI: 10.1111/1365-2656.14173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 08/11/2024] [Indexed: 09/04/2024]
Abstract
Life history trade-offs are one of the central tenets of evolutionary demography. Trade-offs, depicting negative covariances between individuals' life history traits, can arise from genetic constraints, or from a finite amount of resources that each individual has to allocate in a zero-sum game between somatic and reproductive functions. While theory predicts that trade-offs are ubiquitous, empirical studies have often failed to detect such negative covariances in wild populations. One way to improve the detection of trade-offs is by accounting for the environmental context, as trade-off expression may depend on environmental conditions. However, current methodologies usually search for fixed covariances between traits, thereby ignoring their context dependence. Here, we present a hierarchical multivariate 'covariance reaction norm' model, adapted from Martin (2023), to help detect context dependence in the expression of life-history trade-offs using demographic data. The method allows continuous variation in the phenotypic correlation between traits. We validate the model on simulated data for both intraindividual and intergenerational trade-offs. We then apply it to empirical datasets of yellow-bellied marmots (Marmota flaviventer) and Soay sheep (Ovis aries) as a proof-of-concept showing that new insights can be gained by applying our methodology, such as detecting trade-offs only in specific environments. We discuss its potential for application to many of the existing long-term demographic datasets and how it could improve our understanding of trade-off expression in particular, and life history theory in general.
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Affiliation(s)
- Louis Bliard
- Department of Evolutionary Biology and Environmental Studies, Zurich University, Zurich, Switzerland
| | - Jordan S Martin
- Institute of Evolutionary Medicine, Zurich University, Zurich, Switzerland
| | - Maria Paniw
- Department of Evolutionary Biology and Environmental Studies, Zurich University, Zurich, Switzerland
- Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), Seville, Spain
| | - Daniel T Blumstein
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, California, Los Angeles, USA
- The Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
| | - Julien G A Martin
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Daniel H Nussey
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, UK
| | - Dylan Z Childs
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, Zurich University, Zurich, Switzerland
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2
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Barracho T, Hatch SA, Kotzerka J, Garthe S, Schraft HA, Whelan S, Elliott KH. Survival costs of reproduction are independent of energy costs in a seabird, the pelagic cormorant. Ecol Evol 2024; 14:e11414. [PMID: 39045503 PMCID: PMC11264352 DOI: 10.1002/ece3.11414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 04/22/2024] [Accepted: 04/30/2024] [Indexed: 07/25/2024] Open
Abstract
Life-history theory predicts that investment in reproduction should decrease survival (the 'cost of reproduction'). It is often assumed that energy allocation drives such trade-offs, with limited energy available for both reproduction and survival. However, the underlying mechanisms remain poorly understood, maybe because survival costs of reproduction are only apparent when resources are limited. Here, we took advantage of a natural experiment created by fluctuating environmental conditions to compare energy expenditure of a seabird, the pelagic cormorant (Phalacrocorax pelagicus), between contrasting population-scale scenarios of survival costs of reproduction. We used multi-state capture-recapture modelling across 16 years to identify which breeding seasons induced high survival costs (survival ratebreeders < survival ratenon/failed breeders) and we concomitantly estimated energy expenditure of chick-rearing males using time-energy budget models across 4 years. Daily energy expenditure (DEE) of chick-rearing pelagic cormorants varied significantly among years. However, survival costs of reproduction were observed in only 1 year, and contrary to our expectations, variation in DEE was not associated with population-level survival costs. Similarly, at the individual level, DEE in 1 year did not predict the probability of being observed again at the colony in following years (apparent survival). Finally, DEE was independent of brood size and brood age, but older individuals tended to expend less energy than younger ones. Given the lack of an apparent energetic 'cost of reproduction', lower DEE in older birds could be due to improved efficiency rather than avoidance of costs in old birds. Although future studies should account for potential sex-specific energetic constraints by including data on female energy expenditure, we conclude that a direct link between the rate of energy expenditure during breeding and subsequent survival is unlikely in this system.
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Affiliation(s)
- Téo Barracho
- Department of Natural Resource SciencesMcGill UniversitySte‐Anne‐de‐BellevueQuebecCanada
| | - Scott A. Hatch
- Institute for Seabird Research and ConservationAnchorageAlaskaUSA
| | - Jana Kotzerka
- Research and Technology Center (FTZ)University of KielBuesumGermany
| | - Stefan Garthe
- Research and Technology Center (FTZ)University of KielBuesumGermany
| | | | - Shannon Whelan
- Department of Natural Resource SciencesMcGill UniversitySte‐Anne‐de‐BellevueQuebecCanada
| | - Kyle H. Elliott
- Department of Natural Resource SciencesMcGill UniversitySte‐Anne‐de‐BellevueQuebecCanada
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3
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Bliard L, Paniw M, Childs DZ, Ozgul A. Population Dynamic Consequences of Context-Dependent Trade-Offs across Life Histories. Am Nat 2024; 203:681-694. [PMID: 38781530 DOI: 10.1086/730111] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
AbstractTrade-offs are central to life history theory and play a role in driving life history diversity. They arise from a finite amount of resources that need to be allocated among different functions by an organism. Yet covariation of demographic rates among individuals frequently do not reflect allocation trade-offs because of variation in resource acquisition. The covariation of traits among individuals can thus vary with the environment and often increases in benign environments. Surprisingly, little is known about how such context-dependent expression of trade-offs among individuals affect population dynamics across species with different life histories. To study their influence on population stability, we develop an individual-based simulation where covariation in demographic rates varies with the environment. We use it to simulate population dynamics for various life histories across the slow-fast pace-of-life continuum. We found that the population dynamics of slower life histories are relatively more sensitive to changes in covariation, regardless of the trade-off considered. Additionally, we found that the impact on population stability depends on which trade-off is considered, with opposite effects of intraindividual and intergenerational trade-offs. Last, the expression of different trade-offs can feed back to influence generation time through selection acting on individual heterogeneity within cohorts, ultimately affecting population dynamics.
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Layton‐Matthews K, Reiertsen TK, Erikstad K, Anker‐Nilssen T, Daunt F, Wanless S, Barrett RT, Newell MA, Harris MP. Consequences of cross-season demographic correlations for population viability. Ecol Evol 2023; 13:e10312. [PMID: 37456077 PMCID: PMC10338798 DOI: 10.1002/ece3.10312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/20/2023] [Accepted: 07/02/2023] [Indexed: 07/18/2023] Open
Abstract
Demographic correlations are pervasive in wildlife populations and can represent important secondary drivers of population growth. Empirical evidence suggests that correlations are in general positive for long-lived species, but little is known about the degree of variation among spatially segregated populations of the same species in relation to environmental conditions. We assessed the relative importance of two cross-season correlations in survival and productivity, for three Atlantic puffin (Fratercula arctica) populations with contrasting population trajectories and non-overlapping year-round distributions. The two correlations reflected either a relationship between adult survival prior to breeding on productivity, or a relationship between productivity and adult survival the subsequent year. Demographic rates and their correlations were estimated with an integrated population model, and their respective contributions to variation in population growth were calculated using a transient-life table response experiment. For all three populations, demographic correlations were positive at both time lags, although their strength differed. Given the different year-round distributions of these populations, this variation in the strength population-level demographic correlations points to environmental conditions as an important driver of demographic variation through life-history constraints. Consequently, the contributions of variances and correlations in demographic rates to population growth rates differed among puffin populations, which has implications for-particularly small-populations' viability under environmental change as positive correlations tend to reduce the stochastic population growth rate.
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Affiliation(s)
| | | | - Kjell‐Einar Erikstad
- Norwegian Institute for Nature ResearchFRAM CentreTromsøNorway
- Centre for Biodiversity Dynamics CBDNorwegian University of Science and TechnologyTrondheimNorway
| | | | - Francis Daunt
- UK Centre for Ecology & Hydrology, Bush EstatePenicuikUK
| | - Sarah Wanless
- UK Centre for Ecology & Hydrology, Bush EstatePenicuikUK
| | | | - Mark A. Newell
- UK Centre for Ecology & Hydrology, Bush EstatePenicuikUK
| | - Mike P. Harris
- UK Centre for Ecology & Hydrology, Bush EstatePenicuikUK
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Nicol‐Harper A, Doncaster CP, Hilton GM, Wood KA, Ezard THG. Conservation implications of a mismatch between data availability and demographic impact. Ecol Evol 2023; 13:e10269. [PMID: 37475724 PMCID: PMC10353920 DOI: 10.1002/ece3.10269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 07/22/2023] Open
Abstract
Cost-effective use of limited conservation resources requires understanding which data most contribute to alleviating biodiversity declines. Interventions might reasonably prioritise life-cycle transitions with the greatest influence on population dynamics, yet some contributing vital rates are particularly challenging to document. This risks managers making decisions without sufficient empirical coverage of the spatiotemporal variation experienced by the species. Here, we aimed to explore whether the number of studies contributing estimates for a given life-stage transition aligns with that transition's demographic impact on population growth rate, λ. We parameterised a matrix population model using meta-analysis of vital rates for the common eider (Somateria mollissima), an increasingly threatened yet comparatively data-rich species of seaduck, for which some life stages are particularly problematic to study. Female common eiders exhibit intermittent breeding, with some established breeders skipping one or more years between breeding attempts. Our meta-analysis yielded a breeding propensity of 0.72, which we incorporated into our model with a discrete and reversible 'nonbreeder' stage (to which surviving adults transition with a probability of 0.28). The transitions between breeding and nonbreeding states had twice the influence on λ than fertility (summed matrix-element elasticities of 24% and 11%, respectively), whereas almost 15 times as many studies document components of fertility than breeding propensity (n = 103 and n = 7, respectively). The implications of such mismatches are complex because the motivations for feasible on-the-ground conservation actions may be different from what is needed to reduce uncertainty in population projections. Our workflow could form an early part of the toolkit informing future investment of finite resources, to avoid repeated disconnects between data needs and availability thwarting evidence-led conservation.
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Affiliation(s)
- Alex Nicol‐Harper
- Ocean and Earth Science, National Oceanography CentreUniversity of SouthamptonSouthamptonUK
- Wildfowl & Wetlands TrustSlimbridgeUK
| | | | | | | | - Thomas H. G. Ezard
- Ocean and Earth Science, National Oceanography CentreUniversity of SouthamptonSouthamptonUK
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6
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Lyu S, Alexander JM. Compensatory responses of vital rates attenuate impacts of competition on population growth and promote coexistence. Ecol Lett 2023; 26:437-447. [PMID: 36708049 DOI: 10.1111/ele.14167] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 01/29/2023]
Abstract
Competition is among the most important factors regulating plant population and community dynamics, but we know little about how different vital rates respond to competition and jointly determine population growth and species coexistence. We conducted a field experiment and parameterised integral projection models to model the population growth of 14 herbaceous plant species in the absence and presence of neighbours across an elevation gradient (284 interspecific pairs). We found that suppressed individual growth and seedling establishment contributed the most to competition-induced declines in population growth, although vital rate contributions varied greatly between species and with elevation. In contrast, size-specific survival and flowering probability and seed production were frequently enhanced under competition. These compensatory vital rate responses were nearly ubiquitous (occurred in 92% of species pairs) and significantly reduced niche overlap and stabilised coexistence. Our study highlights the importance of demographic processes for regulating population and community dynamics, which has often been neglected by classic coexistence theories.
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Affiliation(s)
- Shengman Lyu
- Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Jake M Alexander
- Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
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Paniw M, García-Callejas D, Lloret F, Bassar RD, Travis J, Godoy O. Pathways to global-change effects on biodiversity: new opportunities for dynamically forecasting demography and species interactions. Proc Biol Sci 2023; 290:20221494. [PMID: 36809806 PMCID: PMC9943645 DOI: 10.1098/rspb.2022.1494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 01/12/2023] [Indexed: 02/23/2023] Open
Abstract
In structured populations, persistence under environmental change may be particularly threatened when abiotic factors simultaneously negatively affect survival and reproduction of several life cycle stages, as opposed to a single stage. Such effects can then be exacerbated when species interactions generate reciprocal feedbacks between the demographic rates of the different species. Despite the importance of such demographic feedbacks, forecasts that account for them are limited as individual-based data on interacting species are perceived to be essential for such mechanistic forecasting-but are rarely available. Here, we first review the current shortcomings in assessing demographic feedbacks in population and community dynamics. We then present an overview of advances in statistical tools that provide an opportunity to leverage population-level data on abundances of multiple species to infer stage-specific demography. Lastly, we showcase a state-of-the-art Bayesian method to infer and project stage-specific survival and reproduction for several interacting species in a Mediterranean shrub community. This case study shows that climate change threatens populations most strongly by changing the interaction effects of conspecific and heterospecific neighbours on both juvenile and adult survival. Thus, the repurposing of multi-species abundance data for mechanistic forecasting can substantially improve our understanding of emerging threats on biodiversity.
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Affiliation(s)
- Maria Paniw
- Department of Conservation Biology and Global Change, Estación Biológica de Doñana (EBD-CSIC), Seville, 41001 Spain
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland
| | - David García-Callejas
- Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), Seville, 41001 Spain
- Instituto Universitario de Investigación Marina (INMAR), Departamento de Biología, Universidad de Cádiz, Campus Río San Pedro, 11510 Puerto Real, Spain
| | - Francisco Lloret
- Center for Ecological Research and Forestry Applications (CREAF), Cerdanyola del Vallès 08193, Spain
- Department Animal Biology, Plant Biology and Ecology, Universitat Autònoma Barcelona, Cerdanyola del Vallès 08193, Spain
| | - Ronald D. Bassar
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Joseph Travis
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Oscar Godoy
- Instituto Universitario de Investigación Marina (INMAR), Departamento de Biología, Universidad de Cádiz, Campus Río San Pedro, 11510 Puerto Real, Spain
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8
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Ogilvie JE, CaraDonna PJ. The shifting importance of abiotic and biotic factors across the life cycles of wild pollinators. J Anim Ecol 2022; 91:2412-2423. [PMID: 36268682 DOI: 10.1111/1365-2656.13825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/19/2022] [Indexed: 12/14/2022]
Abstract
Organisms living in seasonal environments are exposed to different environmental conditions as they transition from one life stage to the next across their life cycle. How different life stages respond to these varying conditions, and the extent to which different life stages are linked, are fundamental components of the ecology of an organism. Nevertheless, the influence of abiotic and biotic factors on different parts of an organism's life cycle is often not accounted for, which limits our understanding of the ecological consequences of environmental change. We investigated the relative importance of climate conditions, food availability, and previous life-stage abundance in an assemblage of seven wild bumble bee species, asking: how do these three factors directly influence bee abundance at each life stage? To do so, we used a 7-year dataset where we monitored climate conditions, floral resources, and abundances of bees in each life stage across the active colony life cycle in a highly seasonal subalpine ecosystem in the Colorado Rocky Mountains, USA. Bee abundance at different life stages responded to abiotic and biotic conditions in a broadly consistent manner across the seven species: the survival and recruitment stage of the life cycle (overwintered queens) responded negatively to longer winters; the growth stage (workers) responded positively to floral resource availability; and the reproductive stage (males) was positively related to the abundance of the previous life stage (workers). Most species also exhibited some idiosyncratic responses. Our long-term examination of annual bumble bees reveals a general set of responses in the abundance of each life stage to climate conditions, floral resource availability, and previous life stage. Across species, these three factors each directly influenced a distinct life stage, illustrating how their relative importance can shift throughout the life cycle. The life-cycle approach that we have taken highlights that important details about demography can be overlooked without considering life-stage-specific responses. Ultimately, it is these life-stage-specific responses that shape population outcomes, not only for animal pollinators but also for many organisms living in seasonal environments.
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Affiliation(s)
- Jane E Ogilvie
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA.,Chicago Botanic Garden, Glencoe, Illinois, USA
| | - Paul J CaraDonna
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA.,Chicago Botanic Garden, Glencoe, Illinois, USA.,Plant Biology and Conservation, Northwestern University, Evanston, Illinois, USA
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9
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Kanno Y, Kim S, Pregler KC. Sub‐seasonal correlation between growth and survival in three sympatric aquatic ectotherms. OIKOS 2022. [DOI: 10.1111/oik.09685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yoichiro Kanno
- Dept of Fish, Wildlife and Conservation Biology, Colorado State Univ. Fort Collins CO USA
- Dept of Forestry and Environmental Conservation, Clemson Univ. Clemson SC USA
| | - Seoghyun Kim
- Dept of Fish, Wildlife and Conservation Biology, Colorado State Univ. Fort Collins CO USA
- Dept of Forestry and Environmental Conservation, Clemson Univ. Clemson SC USA
| | - Kasey C. Pregler
- Dept of Fish, Wildlife and Conservation Biology, Colorado State Univ. Fort Collins CO USA
- Dept of Forestry and Environmental Conservation, Clemson Univ. Clemson SC USA
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Le Coeur C, Yoccoz NG, Salguero-Gómez R, Vindenes Y. Life history adaptations to fluctuating environments: Combined effects of demographic buffering and lability. Ecol Lett 2022; 25:2107-2119. [PMID: 35986627 DOI: 10.1111/ele.14071] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/03/2022] [Accepted: 06/14/2022] [Indexed: 01/07/2023]
Abstract
Demographic buffering and lability have been identified as adaptive strategies to optimise fitness in a fluctuating environment. These are not mutually exclusive, however, we lack efficient methods to measure their relative importance for a given life history. Here, we decompose the stochastic growth rate (fitness) into components arising from nonlinear responses and variance-covariance of demographic parameters to an environmental driver, which allows studying joint effects of buffering and lability. We apply this decomposition for 154 animal matrix population models under different scenarios to explore how these main fitness components vary across life histories. Faster-living species appear more responsive to environmental fluctuations, either positively or negatively. They have the highest potential for strong adaptive demographic lability, while demographic buffering is a main strategy in slow-living species. Our decomposition provides a comprehensive framework to study how organisms adapt to variability through buffering and lability, and to predict species responses to climate change.
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Affiliation(s)
- Christie Le Coeur
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Nigel G Yoccoz
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
| | | | - Yngvild Vindenes
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
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