A life‐history perspective on the demographic drivers of structured population dynamics in changing environments

Koons, David N.; Iles, David T.; Schaub, Michael; Caswell, Hal

doi:10.1111/ele.12628

Cited by 92 publications

(185 citation statements)

References 51 publications

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“…Koons et al. () document the problems and constraints associated with classical LSA and LTRE methods, and then developed a series of transient LTREs that do not require one to assume a stationary environment. These are based on the time‐variant population model n t +1 = A t n t , where A t is a projection matrix containing stage/age‐structured vital rates at time t , and n t denotes a vector of stage/age‐structured abundances.…”

Section: Methodsmentioning

confidence: 99%

“…Koons et al. () demonstrated how the sensitivities can be implemented in a transient LTRE for measuring the contribution of variability in each θ i , including components of population structure, to the temporal variance of

λ_{t}

{contribution}_{{normalθ}_{i}}^{var ({normalλ}_{t})} \approx \underset{j}{false\sum} cov false(θ_{i, t}, θ_{j, t} false) \frac{\partial {normalλ}_{t}}{\partial {normalθ}_{i, t}} \frac{\partial {normalλ}_{t}}{\partial {normalθ}_{j, t}} |_{\overset{normalθ}{true}}

…”

Section: Methodsmentioning

confidence: 99%

“…Recently developed “transient LTREs” formally decompose the contributions of both population structure and vital rates to realized population growth rates in any type of time‐variant environment, and by doing so, provide more accurate inference into the drivers of population dynamics observed during ecological studies (Koons et al. ).…”

Section: Introductionmentioning

confidence: 99%

“…Our primary objective is to demonstrate a framework for gaining robust insight into the demographic drivers of realized population growth rates by joining recently developed transient LTREs (Koons et al. ) with an IPM that incorporates key properties that can affect population dynamics in changing environments: environmental stochasticity (Tuljapurkar ), correlations among vital rates (Doak et al. ), and non‐stationarity (Jenouvrier et al.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the demographic drivers of realized population growth rates

Koons

Arnold

Schaub

2017

Ecological Applications

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133

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Identifying the demographic parameters (e.g., reproduction, survival, dispersal) that most influence population dynamics can increase conservation effectiveness and enhance ecological understanding. Life table response experiments (LTRE) aim to decompose the effects of change in parameters on past demographic outcomes (e.g., population growth rates). But the vast majority of LTREs and other retrospective population analyses have focused on decomposing asymptotic population growth rates, which do not account for the dynamic interplay between population structure and vital rates that shape realized population growth rates (λt=Nt+1/Nt) in time-varying environments. We provide an empirical means to overcome these shortcomings by merging recently developed "transient life-table response experiments" with integrated population models (IPMs). IPMs allow for the estimation of latent population structure and other demographic parameters that are required for transient LTRE analysis, and Bayesian versions additionally allow for complete error propagation from the estimation of demographic parameters to derivations of realized population growth rates and perturbation analyses of growth rates. By integrating available monitoring data for Lesser Scaup over 60 yr, and conducting transient LTREs on IPM estimates, we found that the contribution of juvenile female survival to long-term variation in realized population growth rates was 1.6 and 3.7 times larger than that of adult female survival and fecundity, respectively. But a persistent long-term decline in fecundity explained 92% of the decline in abundance between 1983 and 2006. In contrast, an improvement in adult female survival drove the modest recovery in Lesser Scaup abundance since 2006, indicating that the most important demographic drivers of Lesser Scaup population dynamics are temporally dynamic. In addition to resolving uncertainty about Lesser Scaup population dynamics, the merger of IPMs with transient LTREs will strengthen our understanding of demography for many species as we aim to conserve biodiversity during an era of non-stationary global change.

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Section: Methodsmentioning

confidence: 99%

λ_{t}

{contribution}_{{normalθ}_{i}}^{var ({normalλ}_{t})} \approx \underset{j}{false\sum} cov false(θ_{i, t}, θ_{j, t} false) \frac{\partial {normalλ}_{t}}{\partial {normalθ}_{i, t}} \frac{\partial {normalλ}_{t}}{\partial {normalθ}_{j, t}} |_{\overset{normalθ}{true}}

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding the demographic drivers of realized population growth rates

Koons

Arnold

Schaub

2017

Ecological Applications

Self Cite

133

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show abstract

“…We used transient life table response experiments (LTREs) to decompose temporal variation in population growth rates among vital rate and demographic structure components (Koons et al, , ). Specifically, we considered contributions of adult apparent survival, ϕ ; productivity (of both new recruits/immigrants and survivors from previous time step), RI; first‐year survival/recruitment, ι .…”

Section: Methodsmentioning

confidence: 99%

Integrating broad‐scale data to assess demographic and climatic contributions to population change in a declining songbird

Saracco

Rubenstein

2020

Ecology and Evolution

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Climate variation and trends affect species distribution and abundance across large spatial extents. However, most studies that predict species response to climate are implemented at small spatial scales or are based on occurrence‐environment relationships that lack mechanistic detail. Here, we develop an integrated population model (IPM) for multi‐site count and capture‐recapture data for a declining migratory songbird, Wilson's warbler (Cardellina pusilla), in three genetically distinct breeding populations in western North America. We include climate covariates of vital rates, including spring temperatures on the breeding grounds, drought on the wintering range in northwest Mexico, and wind conditions during spring migration. Spring temperatures were positively related to productivity in Sierra Nevada and Pacific Northwest genetic groups, and annual changes in productivity were important predictors of changes in growth rate in these populations. Drought condition on the wintering grounds was a strong predictor of adult survival for coastal California and Sierra Nevada populations; however, adult survival played a relatively minor role in explaining annual variation in population change. A latent parameter representing a mixture of first‐year survival and immigration was the largest contributor to variation in population change; however, this parameter was estimated imprecisely, and its importance likely reflects, in part, differences in spatio‐temporal distribution of samples between count and capture‐recapture data sets. Our modeling approach represents a novel and flexible framework for linking broad‐scale multi‐site monitoring data sets. Our results highlight both the potential of the approach for extension to additional species and systems, as well as needs for additional data and/or model development.

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Demographic assessment of reintroduced bearded vultures in the Alps: Success in the core, challenges in the periphery

Schaub,

Loercher,

Hegglin

et al. 2024

Ecol Sol and Evidence

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Regular assessment of reintroduced populations is essential to guide management and provide lessons for other reintroduction projects. Bearded vulture Gypaetus barbatus reintroduction in the Alps began in 1986 with the release of the first fledglings, the first successful reproduction was recorded in 1997, and the population has grown steadily since. A previous assessment suggested that no further releases would be required to establish a self‐sustaining population from a demographic point of view. However, this conclusion was based on a small sample size and spatially homogeneous demographic rates of released individuals, which may differ from and be spatially variable among wild‐hatched individuals. Using longitudinal data and breeding site survey data, we constructed an integrated population model to examine the demography of the entire Alpine population, spatially stratified into a core and a periphery. We performed retrospective population analyses to identify demographic reasons for spatial differences in population growth and conducted population viability analyses to assess the impact of future threats and reintroduction options. In 2021, an estimated 172 (CRI: 147–198) females were present in the Alps, of which 65 (CRI: 63–67) were breeders. Adult survival and productivity were higher in the core than in the periphery, so the population grew more strongly in the core than in the periphery. Differences in adult survival contributed most to the differences in population growth between the two areas. The population viability analysis predicts that the Alpine population will double in 10 years but that an increase in the mortality hazard above 0.055 will lead to a population decline. Unlike the population in the core, the population in the periphery is dependent on further releases at this stage. Bearded vulture reintroductions in the Alps have succeeded in creating a self‐sustaining population with higher reproductive success and similar survival probabilities to the autochthonous Pyrenean population. In general, management should focus on preventing further mortality risks. In the periphery, reducing current mortality and increasing reproductive success are essential to make the population independent of releases.

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A life‐history perspective on the demographic drivers of structured population dynamics in changing environments

Cited by 92 publications

References 51 publications

Understanding the demographic drivers of realized population growth rates

Understanding the demographic drivers of realized population growth rates

Integrating broad‐scale data to assess demographic and climatic contributions to population change in a declining songbird

Demographic assessment of reintroduced bearded vultures in the Alps: Success in the core, challenges in the periphery

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