Endogenous spatial heterogeneity in a multi-patch predator-prey system: insights from a field-parameterized model

  • PDF / 1,348,188 Bytes
  • 16 Pages / 595.276 x 790.866 pts Page_size
  • 29 Downloads / 203 Views

DOWNLOAD

REPORT


ORIGINAL PAPER

Endogenous spatial heterogeneity in a multi-patch predator-prey system: insights from a field-parameterized model David Brown 1

&

Andrea Bruder 1 & Miroslav Kummel 2

Received: 16 December 2019 / Accepted: 4 September 2020 # Springer Nature B.V. 2020

Abstract The causes and consequences of spatial heterogeneity in population dynamics are of both theoretical and practical interest. Previously, we described (Kummel et al., Oikos 122:896–906, 2013) a field system in which predation by ladybugs drives the development of strong spatial heterogeneity among aphid populations living on nearby plants. In this paper, we investigate the detailed mechanisms responsible for this phenomenon. We develop a detailed mathematical model of the system, parameterized by an extensive experimental work showing that ladybugs tend to remain on plants with high aphid numbers and are attracted to plants on which ladybugs are actively feeding. The model reproduces important aspects of the field system and allows us to explore how various behavioral features contribute to these dynamics. The results indicate that spatial heterogeneity results from the random aspect of ladybug foraging that causes some large aphid populations to be under-exploited. For parameter values that are unrealistic for our system, the model displays other types of complex dynamics, including predator swarming and chaos. Our study illustrates how a realistic, carefully parameterized model can connect individual behavior to larger scale spatiotemporal dynamics. Keywords Spatial heterogeneity . Predator-prey oscillations . Field data . Multi-patch model . Aphis helianthi . Coccinella septempunctata . Hippodamia convergens

Introduction Spatial heterogeneity in ecology can be defined broadly as the uneven distribution of individuals of one species in space. It has been shown that local interactions can result in the formation of regular, or periodic, spatial patterns on a large scale (Kareiva 1990). A rich body of ecological literature exists pertaining to (1) the mechanisms leading to spatial heterogeneity (e.g., Hastings 1977; Holmes et al. 1994; Rietkerk and van de Koppel 2008; Turing 1952) and (2) the impact that spatial heterogeneity has on the dynamics of (coupled) populations (e.g., Huffaker 1958; Hutchinson 1959; Rosenzweig 1971; Kareiva 1987). The authors are ordered alphabetically. * David Brown [email protected] 1

Department of Mathematics and Computer Science, Colorado College, Colorado Springs, CO, USA

2

Environmental Program, Colorado College, Colorado Springs, CO, USA

Spatial patterns may be generated exogenously, i.e., through some aspect of the underlying ecosystem (e.g., based on underlying resource availability such as water) or endogenously via the interactions of organisms independent of the habitat structure (Rietkerk and van de Koppel 2008). Endogenous patterns are often generated by spatial self-organization, a process by which large-scale patterns emerge as a result of local interactions. Self-generated patterns in ve