Coupling of multiple barriers to gene-flow, such as divergent local adaptation and reproductive isolation, facilitates speciation. However, alleles at loci that contribute to barrier effects can be dissociated by recombination. Models of linkage between diverging alleles often consider elements that reduce recombination, such as chromosomal inversions and alleles that modify recombination rate between existing loci. In contrast, here we consider the evolution of linkage due to close proximity of loci on the same chromosome. Examples of such physical linkage exist in several species, but in other cases strong associations are maintained without physical linkage. We use an individual-based model to study the conditions under which physical linkage between loci controlling ecological traits and mating preferences might be expected to evolve. We modelled a single locus controlling an ecological trait that acts also as a mating cue. Mating preferences are controlled by multiple loci, formed by mutations that are randomly placed in the “genome”, within varying distances from the ecological trait locus, allowing us to examine which genomic architectures spread across the population. 

The dataset details results of simulations of an individual-based model, which was designed to explore evolutionary changes in the relative location of loci contributing to reproductive isolation due to selection pressure against intermediate phenotypes.

The model was impelemented in NetLogo. The model files, including source code and model description (following the ODD protocol) are available for public review at the NetLogo User community website, via the following link:

http://ccl.northwestern.edu/netlogo/models/community/physical_linkage_one_trait_locus

Specifically, simulations were run with the following parameters:

Selection coefficients (s) of 0.5, 0.6, 0.7 and 0.8.

Preference strength factors (pf) of 0.3, 0.6, 1.2 and 2.4.

As a control, additional simualtions were run separately with no recombination applied on offspring chromosomes, (s = 0.5, pf = 0.3).

The output measures were recorded every generation for the duration of 3000 generations.

The data file can be oppened by any program that supports CSV files.