Evolutionary response of a native butterfly to concurrent plantinvasions: Simulation of population dynamics

Abstract

The habitat of the green-veined white butterfly Pieris oleracea in eastern North America has undergone invasions by the exotic plant garlic mustard (Alliaria petiolata), which is replacing native hosts of P. oleracea such as Cardamine diphylla. A. petiolata was originally lethal to most larvae of the native butterfly but during the past 20+ years it has been incorporated successfully into the larval diet, likely through evolutionary change. The region was also invaded by another exotic plant, Cardamine pratensis, on which the native butterfly larvae readily develops, allowing the possibility of population rescue. Further complicating the butterfly's reproductive dynamics, it is multigenerational within a summer, and host plant availability and location change during the summer. Our goal is to model the expected dynamics of the native butterfly population in this evolving, dynamic landscape by using a new bio-inspired paradigm known as membrane computing.

In this context, a Probabilistic Guarded Scripted P system has been designed to model and explore the conditions under which an allele conferring ability of P. oleracea larvae to develop on A. petiolata might have proliferated. The design describes a population dynamics model whose parameter values are derived from experimental and observational data. Our modeling framework is spatially explicit and our model integrates seasonal as well as annual dynamics. The simulation results from our model qualitatively match our field observations and experimental laboratory results, and agree with the results from a previous model on the genotypic adaptation of this butterfly species. From the simulations we identified the likely trajectories for the spatio-temporal distribution of alleles enabling P. oleracea to use the invasive plant species across this selective and phenological mosaic.