The Evolution of Dispersal in Random Environments and The Principle of Partial Control

TL;DR

This paper generalizes the mathematical understanding of dispersal evolution in multiple environments, linking it to genetic principles and introducing the Principle of Partial Control, with implications for empirical and theoretical studies.

Contribution

It extends the two-environment dispersal model to multiple environments and connects the results to the Reduction Principle and the Principle of Partial Control.

Findings

Dispersal evolution is highly sensitive to genetic variation spectrum.

Conditions for increased dispersal can be departures from the Reduction Principle.

Mathematical methods from multiple sources are used to generalize the analysis.

Abstract

McNamara and Dall (2011) identified novel relationships between the abundance of a species in different environments, the temporal properties of environmental change, and selection for or against dispersal. Here, the mathematics underlying these relationships in their two-environment model are investigated for arbitrary numbers of environments. The effect they described is quantified as the fitness-abundance covariance. The phase in the life cycle where the population is censused is crucial for the implications of the fitness-abundance covariance. These relationships are shown to connect to the population genetics literature on the Reduction Principle for the evolution of genetic systems and migration. Conditions that produce selection for increased unconditional dispersal are found to be new instances of departures from reduction described by the "Principle of Partial Control" proposed for the evolution of modifier genes. According to this principle, variation that only partially controls the processes that transform the transmitted information of organisms may be selected to increase these processes. Mathematical methods of Karlin, Friedland, and Elsner, Johnson, and Neumann, are central in generalizing the analysis. Analysis of the adaptive landscape of the model shows that the evolution of conditional dispersal is very sensitive to the spectrum of genetic variation the population is capable of producing, and suggests that empirical study of particular species will require an evaluation of its variational properties.