Filename: 1_Allele_freq Variables: 1. marker_id - Name of the microsatellite marker analysed 2. regime - Experimental regime (low heterozygosity - LH; medium heterozygosity - MH; high heterozygosity - HH) 3. allele frequency - The frequency of alleles occurrence in the tested populations Filename: 2_Pattern_of_plants_infestation Variables: 1. regime - Experimental regime (low heterozygosity - LH; medium heterozygosity - MH; high heterozygosity - HH) 2. rep.id - Repetition ID 3. mites.no - Number of mites found on one plant 4. plant.no - Number of plant examinated Filename: 3_Dispersal_colonisation_data Variables: 1. regime - Experimental regime (low heterozygosity - LH; medium heterozygosity - MH; high heterozygosity - HH) 2. rep.no - Number of repetition within regime 3. rep.id - Repetition ID 4. mite.id - Individual mite ID 5. plant.no - Number of plant examinated 6. dds - Developmental stage of dispersing individual 7. egg.no - Number of eggs laid 8. F1_f.sex - Number of individuals developing into females 9. F1_m.sex - Number of individuals developing into males Filename: 4_Sex_ratio Variables: 1. regime - Experimental regime (low heterozygosity - LH; medium heterozygosity - MH; high heterozygosity - HH) 2. source - The source of the tested population (predisperal or postdispersal) 3. rep.id - Repetition ID 4. females.no - Number of females found in a population 5. males.no - Number of males found in a population

The study was financially supported by the National Science Centre in Poland (grant no. UMO-2017/27/N/NZ8/00305) and a grant from the Dean of the Faculty of Biology, Adam Mickiewicz University, Poznań (GDWB-07/2018) awarded to AL. AL scholarships were funded by European Social Funds (POWR.03.02.00–00–I006/17), the National Science Centre, Kraków (PhD scholarship no. 2019/32/T/NZ8/00151) and the Adam Mickiewicz University Foundation (awarded in 2019/2020). AS was involved in this work while supported by the National Science Centre (grant no. 2016/21/B/NZ8/00786).