A Constraint-based model of Dynamic Island Biogeography: environmental history and species traits predict hysteresis in populations and communities

Trevor S. Fristoe,Meghan A. Balk,Robert P. Anderson,Joseph R. Burger

doi:10.21425/f5fbg44383

Abstract

A Constraint-based model of Dynamic Island Biogeography: environmental history and species traits predict hysteresis in populations and communities We present a conceptual model that shows how hysteresis can emerge in dynamic island systems given simple constraints on trait-mediated processes. Over time, many islands cycle between phases of increasing and decreasing size and connectivity to a mainland species pool. As these phases alternate, the dominant process driving species composition switches between colonization and extinction. Both processes are mediated by interactions between organismal traits and environmental constraints: colonization probability is affected by a species’ ability to cross the intervening matrix between a population source and the island; population persistence (or extinction) is driven by the minimum spatial requirements for sustaining an isolated population. Because different suites of traits often mediate these two processes, similar environmental conditions can lead to differences in species compositions at two points of time. Thus, the Constraint-based model of Dynamic Island Biogeography (C-DIB) illustrates the possible role of hysteresis—the dependency of outcomes not only on the current system state but also the system’s history of environmental change—in affecting populations and communities in insular systems. The model provides a framework upon which additional considerations of lag times, biotic interactions, evolution, and other processes can be incorporated. Importantly, it provides a testable framework to study the physical and biological constraints on populations and communities across diverse taxa, scales, and systems.

Highlights

The Earth is dynamic and many natural systems cycle in predictable ways
As these systems undergo environmental cycles, changes in the insular community composition are dominated by two distinct phases: i) colonization leads to higher species richness during periods of increasing connectivity as the intervening matrix separating an island from the mainland becomes shorter and/or easier to traverse; and ii) extinction reduces species richness during periods of decreasing area as an island’s capacity to support populations declines (Box 1)
We present a conceptual model describing how the environmental cycles that drive island dynamics can shift the ecological constraints that influence colonization and extinction

Summary

Introduction

The Earth is dynamic and many natural systems cycle in predictable ways. Landscapes change over space and time, resulting in patches of habitats that expand and contract, appear and disappear, connect and disconnect. As these systems undergo environmental cycles, changes in the insular community composition are dominated by two distinct phases: i) colonization leads to higher species richness during periods of increasing connectivity as the intervening matrix separating an island from the mainland becomes shorter and/or easier to traverse; and ii) extinction reduces species richness during periods of decreasing area as an island’s capacity to support populations declines (Box 1).

Results

Conclusion