Adaptive-dynamics models in regnans

theory

regnans includes four small adaptive-dynamics models with explicit invasion- fitness equations and demographic equilibria. They run quickly and have known solutions, which makes them useful for learning the workflow and checking the community-assembly and attractor algorithms. The same calculations are much more demanding in the full, size-structured plant model.

Read the adaptive dynamics page first for the main ideas. Each page below then introduces one model, explains its fitness equation, and works through the corresponding regnans code.

Model	Ecological setting	Main outcome
DD99	Competition for a continuous resource	Branching when competition is more local than resource use
GK98	Soft selection across three habitats	Either one stable strategy or a protected pair of strategies
GM99	Seed-size competition for safe sites	Coexistence of small- and large-seeded strategies
JJ12	Competition over migratory arrival time	One stable arrival strategy before the seasonal optimum

All single-model pages use the same pipeline:

library(regnans)
h <- harness_dd99()                                   # or _gk98 / _gm99 / _jj12
community_start(bounds(x = c(-2, 2)), harness = h) |>
  community_solve_singularity_1D()                    # -> evolutionary attractor

The DD99, GK98, and GM99 models also support resident communities containing more than one strategy. You can therefore move beyond pairwise invasibility plots and run the full community-assembly algorithm. The examples show how branching and limiting similarity build a multi-strategy community, including a two-trait version of DD99.

Rendering these pages requires regnans (and its dependency plant) to be installed, not just loaded from source.