Rapid and strong population genetic differentiation and genomic signatures of climatic adaptation in an invasive mealybug

Aim: A growing number of studies suggest that adaptation of invasive species play key roles in their successful establishment in novel environments. However, adaptation of invasive species to climatic conditions remains poorly characterized. This study aimed to understand the population genetic structure produced by the cotton mealybug Phenacoccus solenopsis invasion and to identify preliminary signals of selection during its range expansion.

Location: China.

Methods: We examined genetic structure of 11 population across China using SNPs, microsatellites and a segment of mitochondrial cox1 gene. ADMIXTURE, STRUCTURE and DAPC were used to infer population genetic structure; the dispersal routes were reconstructed by the DIYABC; SNPs potentially related to climate adaptation were identified by using four population differentiation methods and three environmental association methods.

Results: Strong genetic differentiation was found among populations with FST values ranging from 0..., Sample collection and DNA extraction

Female adults of P. solenopsis were collected from 11 locations across its distribution areas in China in 2017 (Table S1, Fig. 1a). Genomic DNA was extracted from the whole individual of P. solenopsis using DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany) with an additional step of RNase treatment. Voucher DNA of specimens was stored in the Integrated Pest Management Laboratory of Beijing Academy of Agriculture and Forestry Sciences at -80°C.

SNP genotyping

We used the double-digest restriction site-associated DNA (ddRAD) method to develop genome-wide SNP markers (Peterson, Weber, Kay, Fisher, & Hoekstra, 2012). To select the endonuclease enzymes for digestion, we simulated digestion using the draft genome of P. solenopsis (Ma et al., 2019) as a reference through the DDsilico program (Rašić, Filipović, Weeks, & Hoffmann, 2014). Libraries were constructed for each individual as described elsewhere (Peterson et al., 2012). Twent...,