Investigating the Dynamics of Elk Population Size and Body Mass in a Seasonal Environment Using a Mechanistic Integral Projection Model

Lachish, Shelly; Brandell, Ellen E.; Craft, Meggan E.; Dobson, Andrew; Hudson, Peter J.; MacNulty, Daniel R.; Coulson, Tim

doi:10.1086/708723

Cited by 8 publications

(41 citation statements)

References 92 publications

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“…Such models capture the indirect effects of two species competing for a resource or other limiting factor; the resource or shared predator are not explicitly included in models. Direct effects can be incorporated into models by formulating demographic, development, and inheritance functions of focal species to be functions of the size and structure of interacting resource or consumer species on neighbouring trophic levels (Lachish et al 2020).…”

Section: Conditions Required For Ecological and Evolutionary Stationaritymentioning

confidence: 99%

“…Discrete time models called integral projection models (IPMs) of phenotypic trait distributions were initially developed by (Easterling et al 2000). Since then, models have been extended to incorporate explicit genotype-phenotype maps (Coulson et al 2011, Rees and Ellner 2019, frequency-dependence (Schindler et al 2015), density-dependence (Rees et al 2014), abiotic variation (Ellner and Rees 2006), and species interactions (Adler et al 2010, Bassar et al 2017, Lachish et al 2020). These models have been used to study the dynamics of populations and distributions of phenotypic traits, breeding values and additive genotypes, non-additive genotypes, and life history strategies.…”

Section: Population Models Of Ecological and Evolutionary Stasismentioning

confidence: 99%

“…Traits such as this require demographic, development, and inheritance functions, but the inheritance functions do not need to explicitly include rules for genetic inheritance for the trait itself because these traits are emergent consequences of an individual's resource accrual trait value and the environment. Similarly, development functions can be specified to be determined by the value of resource accrual traits and the quantity of resources accrued (Lachish et al 2020).…”

Section: Population Models Of Ecological and Evolutionary Stasismentioning

confidence: 99%

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Environmental perturbations and transitions between ecological and evolutionary equilibria: an eco-evolutionary feedback framework

Coulson¹

2021

Peer Community Journal

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Section: Conditions Required For Ecological and Evolutionary Stationaritymentioning

confidence: 99%

Section: Population Models Of Ecological and Evolutionary Stasismentioning

confidence: 99%

Section: Population Models Of Ecological and Evolutionary Stasismentioning

confidence: 99%

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Environmental perturbations and transitions between ecological and evolutionary equilibria: an eco-evolutionary feedback framework

Coulson¹

2021

Peer Community Journal

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“…Changes in environmental conditions or perturbations, such as hunting, can influence populations via feedback mechanisms (Lachish et al, 2020). Feedback loops in populations occur when…”

Section: Introductionmentioning

confidence: 99%

“…Changes in environmental conditions or perturbations, such as hunting, can influence populations via feedback mechanisms (Lachish et al, 2020 ). Feedback loops in populations occur when demographic rates depend on current population properties (e.g., population size or composition).…”

Section: Introductionmentioning

confidence: 99%

The interplay between hunting rate, hunting selectivity, and reproductive strategies shapes population dynamics of a large carnivore

Walle

Pelletier

Zedrosser

et al. 2021

Evolutionary Applications

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Harvest, through its intensity and regulation, often results in selection on female reproductive traits. Changes in female traits can have demographic consequences, as they are fundamental in shaping population dynamics. It is thus imperative to understand and quantify the demographic consequences of changes in female reproductive traits to better understand and anticipate population trajectories under different harvest intensities and regulations. Here, using a dynamic, frequency-dependent, population model of the intensively hunted brown bear (Ursus arctos) population in Sweden, we quantify and compare population responses to changes in four reproductive traits susceptible to harvest-induced selection: litter size, weaning age, age at first reproduction, and annual probability to reproduce. We did so for different hunting quotas and under four possible hunting regulations: (i) no individuals are protected, (ii) mothers but not dependent offspring are protected, (iii) mothers and dependent offspring of the year (cubs) are protected, and (iv) entire family groups are protected (i.e., mothers and dependent offspring of any age). We found that population growth rate declines sharply with increasing hunting quotas. Increases in litter size and the probability to reproduce have the greatest potential to affect population growth rate.Population growth rate increases the most when mothers are protected. Adding protection on offspring (of any age), however, reduces the availability of bears for hunting, which feeds back to increase hunting pressure on the nonprotected categories of individuals, leading to reduced population growth. Finally, we found that changes in reproductive traits can dampen population declines at very high hunting quotas, but only when protecting mothers. Our results illustrate that changes in female reproductive traits may have context-dependent consequences for demography. Thus, to predict population consequences of harvest-induced selection in wild populations, it is critical to integrate both hunting intensity and regulation, especially if hunting selectivity targets female reproductive strategies.

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Investigating tritrophic interactions using bioenergetic demographic models

Passoni,

Coulson,

Cagnacci

et al. 2023

Ecology

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A central debate in ecology has been the long running discussion on the role of apex predators in affecting the abundance and dynamics of their prey. In terrestrial systems, research has primarily relied on correlational approaches, due to the challenge of implementing robust experiments with replication and appropriate controls. A consequence of this is that we largely suffer from a lack of mechanistic understanding of the population dynamics of interacting species that can be surprisingly complex. Mechanistic models offer an opportunity to examine the causes and consequences of some of this complexity. We present a bioenergetic mechanistic model of a tritrophic system where the primary vegetation resource follows a seasonal growth function, and the herbivore and carnivore species are modelled using two integral projection models (IPMs) with body mass as the phenotypic trait. Within each IPM, the demographic functions are structured according to bioenergetic principles, describing how animals acquire and transform resources into body mass, energy reserves and breeding potential. We parameterise this model to reproduce the population dynamics of grass, elk and wolves in northern Yellowstone (USA), and investigate the impact of wolf reintroduction on the system. Our model generated predictions that closely matched the observed population sizes of elk and wolf in Yellowstone prior to and post wolf reintroduction. The introduction of wolves into our basal grass‐elk bioenergetic model resulted in a population of 99 wolves, and a reduction in elk numbers by 61% (from 14,948 to 5,823) at equilibrium. In turn, vegetation biomass increased by approximately 25% in the growing season and more than 3‐fold in the non‐growing season. The addition of wolves to the model caused the elk population to switch from being food‐limited to being predator‐limited, and had a stabilising effect on elk numbers across different years. Wolf predation also led to a shift in the phenotypic composition of the elk population, via a small increase in elk average body mass. Our model represents a novel approach to the study of predator‐prey interactions. Explicitly considering and linking bioenergetics, population demography and body mass phenotypes can provide novel insights into the mechanisms behind complex ecosystem processes.

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Investigating the Dynamics of Elk Population Size and Body Mass in a Seasonal Environment Using a Mechanistic Integral Projection Model

Abstract: Investigating the dynamics of elk population size and body mass in a seasonal environment using a mechanistic integral projection model. Running title: Elk responses to environmental change.

Cited by 8 publications

References 92 publications

Environmental perturbations and transitions between ecological and evolutionary equilibria: an eco-evolutionary feedback framework

Environmental perturbations and transitions between ecological and evolutionary equilibria: an eco-evolutionary feedback framework

The interplay between hunting rate, hunting selectivity, and reproductive strategies shapes population dynamics of a large carnivore

Investigating tritrophic interactions using bioenergetic demographic models

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