Joint evolution of dispersal and connectivity

Functional connectivity, the realized flow of individuals between the suitable sites of a heterogeneous landscape, is a prime determinant of the maintenance and evolution of populations in fragmented habitats. While a large body of literature examines the evolution of dispersal propensity, it is less known how evolution shapes functional connectivity via traits that influence the distribution of the dispersers. Here we use a simple model to demonstrate that, in a heterogeneous environment with clustered and solitary sites (i.e., with variable structural connectivity), the evolutionarily stable population contains strains that are strongly differentiated in their pattern of connectivity (local vs global dispersal), but not necessarily in the fraction of dispersed individuals. Also during evolutionary branching, selection is disruptive predominantly on the pattern of connectivity rather than on dispersal propensity itself. Our model predicts diversification along a hitherto neglected axis of dispersal strategies and highlights the role of the solitary sites – the more isolated and therefore seemingly less important patches of habitat – in maintaining global dispersal that keeps all sites connected.
Methods
This zip folder contains code and data files provided as electronic enhancements to the paper "Joint evolution of dispersal and connectivity" by P. Karisto and E. Kisdi, published in Evolution.

Content of the zip folder:

- Six Mathematica notebooks containing the model analysis

    monomorphic_boundary_analysis_annotated.nb

    monomorphic_singularities_annotated.nb

    isocline_plots_annotated.nb

    direction_of_disruptive_selection_annotated.nb

    dimorphic_singularities_annotated.nb

    canonical_equation_annotated.nb

- The data file data_file.csv with the coordinates of dimorphic singularities of the form ((d1,0),(d2,q2)) with q2<1 (cited in Section 5 of the Electronic Appendix of the paper, published on the website of the journal Evolution)