Kin competition accelerates experimental range expansion in an arthropod herbivore

In this study, we show that in a spider mite species, Tetranychus urticae, genetic changes do not drive experimental range expansions. We performed two experiments, each with two treatments, wherein mite populations were allowed to expand their habitat range. In a first experiment, we either replaced migrating females with females from the parental stock populations (Replacement From Stock) or left the migrants unmanipulated (Control). In a second experiment, we compared the range expansions of non-evolving, genetically inbred, populations (Iso) with those of evolving, genetically diverse, populations (Mix). Transcriptomic analysis supported other lines of evidence showing that experimental range expansion was driven by kin competition and not by genetic changes (see also Van Petegem et al, 2017). Only 21 differentially expressed genes were found. Here, we report the transcriptomes of female mites in the Control and Mix populations that migrated to the end patch of the population range with those that stayed at the home patch. These comparisons are referred to as: Mix-end_vs_Mix-core (5 replicates) and Control-end _vs_Control-core (6 replicates).