GENERAL INFORMATION

This README.txt file was updated on 23/10/2025.

A. Paper associated with this archive

Citation: Murray, K.I., Townley, S. and Hodgson, D., 2025. A Disturbing View of Life History Evolution. The American Naturalist.

Brief abstract: Species’ lifetime schedules of survival, growth and reproduction generally assort along a principal axis of variation called the “fast-slow” continuum, with positions attributed to the value of producing many, fragile offspring early, versus few, high-quality offspring later. Fast species are classically associated with surplus or pulsed resources, and slow species with stable, limiting resources. Here we demonstrate that the fast-slow continuum can also emerge as a zone of highest fitness in the face of unpredictable, catastrophic, demographic disturbances, regardless of resource supply, competition, or life history trade-offs. Our resilience framework measures resistance, recovery, and fitness of stage-structured life histories in stochastically disturbed environments. Structured disturbances favour either fast or slow life history variants due to their respective weak resistance and fast recovery, or strong resistance and slow recovery. Demographic disturbance regimes might therefore play an important role in shaping nature’s diversity of life histories. The resilience framework is a useful tool for understanding species’ demographic and evolutionary responses to environmental fluctuations and change.

B. Originators

Katie I. Murray¹, Stuart Townley² and Dave Hodgson¹

¹Centre for Ecology and Conservation, Faculty of Environment, Science and Economy, University of Exeter, Penryn Campus, Penryn, Cornwall UK

²Department of Earth and Environmental Sciences, and Environment and Sustainability Institute, Faculty of Environment, Science and Economy, University of Exeter, Penryn Campus, Penryn, Cornwall UK

C. Contact information

Name: Dave Hodgson (corresponding author)

Address: University of Exeter, Penryn Campus, Penryn, Cornwall UK

Email: d.j.hodgson@exeter.ac.uk

DATA & CODE FILE OVERVIEW

There are two models each with self-contained code files (for simulations and figure composition) and the orginal figures (Figures 1-6). The two following code files will generate the figures used on software framework R with all necessary packages called in the start of the script. Just run the whole code from what it looks like for each model. No data is needed as it is simulated within the code scripts; the included supplemental files contain all of the information necessary to support the research findings.

1. Model_1__Figures_123.R: Stage-structured productivity (Figures 1-3)
2. Model_2__Figures_456.R: Delayed maturation model (Figures 4-6)

All figure PDFs are available on Zenodo. See the Related Work entry for Supplemental Information.

Figure_1.pdf: Heatmaps showing the stochastic growth rates for combinations of adult (s2) and juvenile (s1) survival, with contours describing adult productivity (p2) and panels for different values of juvenile productivity (p1). All populations disturbed by stage-specific, Uniform-distributed, proportional culls with per-timestep probability f = 0.2. The yellow diamond symbol represents the maximum parameter combination over all plots. The areas of block white represent the parameter combinations that are not biologically feasible (s1p1 > 1.2).

Figure_2.pdf: Heatmaps showing demographic resistance, measured as the mean of the log of the ratio of disturbed to undisturbed population size per timestep, for combinations of adult (s2) and juvenile (s1) survival, with contours describing adult productivity (p2) and panels for different values of juvenile productivity (p1). All populations disturbed by stage-specific, Uniform-distributed, proportional culls with per-timestep probability f = 0.2. The yellow diamond symbol represents the maximum parameter combination over all plots. 

Figure_3.pdf: Heatmaps showing demographic recovery, measured as the mean of the log of the ratio of projected to disturbed population size per timestep, for combinations of adult (s2) and juvenile (s1) survival, with contours describing adult productivity (p2) and panels for different values of juvenile productivity. All populations disturbed by stage-specific, Uniform-distributed, proportional culls with per-timestep probability f = 0.2. The yellow diamond symbol represents the maximum parameter combination over all plots.

Figure_4.pdf: Heatmaps showing the stochastic growth rates for combinations of adult (s2) and juvenile (s1) survival, with contours describing adult productivity (p2) and panels for different values of maturation rate (φ). All populations disturbed by stage-specific, Uniform-distributed, proportional culls with per-timestep probability f = 0.2. The yellow diamond symbol represents the maximum parameter combination over all plots.

Figure_5.pdf: Heatmaps showing demographic resistance, measured as the mean of the log of the ratio of disturbed to undisturbed population size per timestep,  for combinations of adult (s2) and juvenile (s1) survival, with contours describing adult productivity (p2) and panels for different values of maturation rate (φ). All populations disturbed by stage-specific, Uniform-distributed, proportional culls with per-timestep probability f = 0.2. The yellow diamond symbol represents the maximum parameter combination over all plots.

Figure_6.pdf: Heatmaps showing demographic recovery, measured as the mean of the log of the ratio of projected to disturbed population size per timestep,  for combinations of adult (s2) and juvenile (s1) survival, with contours describing adult productivity (p2) and panels for different values of maturation rate (φ). All populations disturbed by stage-specific, Uniform-distributed, proportional culls with per-timestep probability f = 0.2. The yellow diamond symbol represents the maximum parameter combination over all plots.